JULY 2015

STATE OF TECHNOLOGY REPORT

Machine SafetyFrom new trends in technology to the

steadfast basics, we tell you what

you need know about machine

safety for today and the future

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Table of ContentsMake risk assessment your critical first step in functional machine safety design 5

Trends in TechnologyHow Technology Is Making Machines Safer 7Where’s Your Safety Now? 14Programmable Safety Cuts Costs And Adds Capabilities 16Manufacturing Workers - The Next Generation 21Machine Safety Is Elemental For New Automated Systems 23

Back to the BasicsConsider The Need For Safety Switches 29What’s Your Machine Safety Cost? 31The Importance Of Machinery Safety Labels 33Help Machine Safety Break Free Of The Past 35

Technology in ActionMachine Safety Pays Its Way 37Real Machine Safety Applications In The Spooky Garage 38Buckle Up With Built In Safety 40

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Newark 6www.newark.com/automation

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Euchner 15www.euchner-usa.com

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Pepperl+Fuchs 36www.pepper-fuchs.com/purge

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Machine safety protects employees from unsafe conditions and known hazards, reduces costs such as medical and insurance expenses, helps

companies to comply with regional or international regulations and improves productivity or avoids com-plete machine shutdown.

Sometimes, machine safety guidance can be con-flicting, such as conceptual differences in the risk as-sessment and grading process between a PMMI stan-dard and an RIA standard, and that can be confusing.

Companies make safety a top priority, but inci-dents continue to happen. Machine guards get by-passed because what is under them needs a lot more attention than the designer intended. For example, jams happen. Bypassing a guard for ease of machine use is unacceptable behavior, but there it is, unless your facility operates autonomously without any hu-man interaction.

Safety devices can be scary to engineers and main-tenance crews, as well. People often hold their breath the second the word “safety” is mentioned. When safety was in its infancy, many companies thought compliance meant putting up a fence and a switch on the door. When human operators started dis-abling barriers and cheating the technology to avoid production stoppages, it sometimes meant dismem-berment or, in the worst case, death. Devices now allow machines to be safer and remain productive.

The U.S. Department of Labor’s Occupational Safety and Health Administration (OSHA) provides the standards that apply to machine guarding of pro-duction equipment in the United States. The lock-out/tagout (LOTO) standard applies when employees

perform maintenance and service to production equipment, and it requires the prevention of unex-pected energization of equipment. That’s done by re-moving all energy from a machine and locking the en-ergy sources in the off state whenever employees must be in a potentially hazardous location.

The exception to LOTO allows alternative mea-sures when machine access is required during minor servicing. Alternative measures include integrated machine safety solutions.

LOTO is extremely safe, but the problem is that somebody has to actually do it. OSHA lists the failure to control hazardous energy among its top citations. Users often overcompensate for this by putting out an edict to the OEM or system integrator to set the bar very high, which often increases the cost unnec-essarily. The problem is that engineers assigned to implement machine safety on equipment aren’t com-fortable with it.

Functional safety design includes multiple steps that assess risks and anticipate safety needs. It’s im-portant to assess risks by identifying limits and haz-ards early in the process so the safety is designed into the machine, rather than added as an afterthought.

This State of Technology Report explores in greater detail these and other technology trends in the arena of machine safety. Drawn from the most recent arti-cles published in the pages of Control Design, this special report includes articles on emerging trends and basic primers illustrating the latest technology in action. We hope that you find it useful.

- The Editors

Make risk assessment your critical first step in functional machine safety design

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How technology is making machines saferFind out how spending money on safety technology makes dollars and sense

By Hank Hogan, contributing editor

For sheet metal fabricator Marlin Steel, spending money on safety technology makes dollars and sense. President Drew Greenblatt says the Balti-

more, Maryland-based company invests millions in automation because it increases productivity, cuts cycle time and improves quality. It also makes man-ufacturing better in other ways.

“We’re able to ship product that’s made in a safer fashion because our employees are less likely to get hurt,” Greenblatt says. “We’ve gone more than 2,295 days without a safety incident. We attribute a lot of that to the technology and the robots.”

A non-automated company of a similar size would typically have had 18 to 30 injuries over that same span, according to Greenblatt. Thanks to its safety record, Marlin Steel saves money in insurance premiums and is better able to retain skilled employees, who value a company that demonstrates it values them.

But, at the same time, there are aspects of safety technology that Greenblatt would like to see im-proved. Chief among these are alerts that warn of attempts to defeat or bypass safety systems. Another desired innovation involves better sensors and sys-tems, largely as a means to allow humans and robots to work more closely together.

Safety in numbersAs Greenblatt demonstrates, there’s a demand for safety technology, particularly if it’s part of an over-all automation and productivity package. However, there also is room for improvement.

Sales of safety sensors and switches will reach $3.3

billion yearly worldwide by 2020, according to a new report from  analyst firm IndustryARC. The heavy machinery used in manufacturing has the potential to crush, amputate, burn or blind, causing severe workplace injuries. That makes the use of sensors a necessity to protect workers, and it explains the 3.1% compound annual growth rate in sales, says Indus-try Consultant Ravi Medichelmela.

Willoughby, Ohio-based Bevcorp  is one reason for the growth in safety-related technology. That is due to a philosophy followed by the maker of rotary fillers, blending equipment and handling parts for the beverage industry (Figure 1).

FILL AND RINSE

Figure 1: This bottle filler is made safer with safety guards,

convenience lights for diagnostics, locking switches and clear

radial guarding for full visibility.

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“We design for safety-standard compliance, but we go above that by adding features and functionality and using the latest technologies, which gives the flexibil-ity to maximize uptime,” says Eric Hendrickson, engi-neering manager for electrical and mechanical.

On the technology front, the company makes use of  Ethernet-based safety PLCs  and similar controls, finding this improves diagnostics and adds flexibility. Because of the technology, something like a door, for example, can be added without having to run so many wires. That gives the OEM the capability to better adapt a machine to a specific customer or situation.

As for other design changes technology now en-ables, Hendrickson cites what was done with a bowl used in the filling process. The product within it has to be maintained at a certain level, with more peri-odically added in a foam-free fashion. Previously, a product change or adjustment required stopping a machine, opening up guarding, making a mechani-cal adjustment, closing up the machine and starting it up again—a time-consuming sequence that might have to be repeated. Now, an electronic level con-

trol system that sits inside the guarding and commu-nicates wirelessly enables adjustments to be made without stopping the machine at all.

Bevcorp uses products from Rockwell Automation, and Hendrickson says these offerings have evolved over time. That allows OEMs to offer more diag-nostics and options. Looking forward, Hendrickson notes that safety technology vendors are trying to make devices that cannot be circumvented through the addition of redundancy and double-checking of conditions, all to better spot attempts at altering or bypassing safeguards (Figure 2).

Matthew Miller, a machine safety specialist at ABB Jokab Safety Products, notes that making a true calculation about the cost and payback of safety should account for everything, and that leads to one conclusion (Figure 3). “The rewards easily outweigh the investment,” says Miller. “An unsafe machine can result in injured employees, produc-tion downtime, paying workers’ compensation, law-suits and fines and increased insurance premiums, just to name a few.”

IMPROVED DIAGNOSTICSFigure 2: Bevcorp makes use of Ethernet-based safety PLCs

and similar controls, finding this improves diagnostics and

adds flexibility.

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PALLETIZEFigure 3: Machine safety equipment makes this robotic

palletizing cell handling heavy paint drums safe and

running at peak efficiency.

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Safety after the factInnovations are changing how safety technology is implemented. Take the case of MGS Automation, a Germantown, Wisconsin-based provider of custom automation systems. As part of an upgrade, MGS opted to go with distributed safety I/O, choosing to do so as a way to save money while meeting safety requirements (Figure 4).

“Since this particular machine consisted of many independent modules and sections, each with unique safety requirements, we wanted to localize hardware on each module and minimize the wir-ing required back to the main control cabinet,” says Craig Nisleit, electrical engineer at MGS.

To do this, MGS used products from  Phoenix Contact USA  to create a distributed logic module with communication handled by a special protocol running over an already-installed standard network. Called a black or grey channel, this approach yields safe communication over a standard automation protocol, says Zachary Stank, a safety product mar-keting specialist at Phoenix Contact.

This method allows an upgrade and improved safety to be added to an existing machine without demanding a complete redesign. However, it does require care be taken.

“It’s just like adding I/O to a system,” Stank says. “The more I/O you add to a PLC, it affects how quickly that PLC can respond.”

That response time plays a role in keeping a ma-

chine running safely. For all safety systems, there are watchdog timers in place to make sure that I/O is functioning correctly and communicating as re-quired. If the timer is too short, then the watchdog will trip and cause a machine to go down, perhaps unnecessarily. However, if a watchdog timer has the opposite problem, then it may take too long to bring a machine to a safe stop.

Setting a watchdog timer up so that it’s in the sweet spot with regard to duration requires knowing how long a safety control system takes to react. The other bit of information that’s needed is the nature of the dangers the machine presents.

Finding that out requires a risk assessment, something that should be done for all automated machines and use scenarios. Chris Gerges, CEO of safety assessment and integration firm  Safe-T-Sense of Schaumburg, Illinois, notes that the list of job functions to consider includes operators, main-tenance, engineering, management and EHS. Part of the consideration must also be that in some cases people may try to defeat safeguards, so the system must take this into account and protect against it.

In the United States, the ISO 13849 standard is having an impact, according to Gerges. Large users are requiring machine builders to comply with this. Unfortunately, the probabilistic approach the stan-dard takes to safety can make following it challeng-ing for smaller machine builders. There are several aspects to take into account when determining the safety performance level that the standard calls for, including the circuit category structure, mean time to dangerous failure, diagnostic coverage, common cause failures and systematic faults. These all play a role in the calculations.

The best solution for reducing risk is to design out the hazard. If that cannot be done, then “it’s really going to require proper engineering to make sure that the device is wired properly in a safety control circuit and actually stops motion in a reliable man-ner,” says Gerges.

DISTRIBUTED SAFETY

Figure 4: With a distributed safety solution, MGS

Automation could distribute I/O across various locations on

the machine while maintaining a single point of control.

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Safety comboStill, other advances enable an integrated platform for motion control, other control functions and safety, which can lead to significant savings. Avon, Massachusetts-based  i-Web  has put this capability to work in its systems for the processing and finish-ing of commercial print and packaging products.

These systems consist of machines that fold, cut, perforate, glue and stack printed items, but the exact configuration varies by customer and application. One commonality is the need to control a large number of motion axes, which requires quite a bit of data throughput (Figure 5). Depending upon the printing process, there may be a need to precisely synchronize multiple direct-driven rollers.

On the safety front, i-Web implements emergency stop, interlock and other safety-related systems. Since modules can be added to or removed from each print-ing line, every module must have its own safety system.

Thanks to a fast-enough fieldbus and sufficiently capable safety and control components, i-Web was able to integrate control and functional safety. By do-ing so, the company avoided implementing a separate safety network and was able to achieve some signifi-cant savings, says President Bob Williams. “Required electrical cabinet space has dropped by 50%,” he says. “In terms of the automation and controls equip-ment, there has been an impressive 75% reduction in time required for electrical installation in the field.”

For its integrated approach, i-Web chose a PC- and EtherCAT-based control platform from Beckhoff Au-tomation. This was done, in part, because this tech-nology enabled communication with up to 100 servo motor axes in 100 µs, Williams says. This resolved the bottleneck created by the fieldbus previously used. It also increased safety, since it takes less time to react to dangerous conditions and initiate a stop sequence.

Kurt Wadowick, Beckhoff I/O and safety special-ist, notes that safety was originally a hardware solu-tion. When a fault occurred in any moderately com-plex system, it took time to study a circuit schematic,

trace wiring and signals and measure voltages in or-der to finally figure out what had happened and then correct it.

Now safety can increasingly be implemented in software. That makes it is easier to integrate with other control functions. Less wiring is needed, and cost is reduced. Also, troubleshooting is much easier and faster. “Now, in our function blocks, we’re giv-ing you all the diagnostics of every function block, bringing it up to the HMI screen,” Wadowick says.

He adds that in an integrated setup the safety con-troller runs on a separate processor from the PLC. This means that changes can be made to the control software without impacting safety operations. Work-ing with the two systems is made easier because the PLC code, hardware configuration, motion control and safety run under one software platform.

DATA EVERYWHERE

Figure 5: Using an integrated control and functional

safety system, i-Web implements a wide range of

e-stops, safe stop functions, guard interlocks and other

safety equipment

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That demands a degree of awareness of the dif-ferences between how the control system treats cer-tain items and how something seemingly very simi-lar is handled in the safety environment, Wadowick cautions. For instance, the output associated with a timer-off function in a PLC will stay on until a spe-cific time has elapsed, no matter what. In a safety system, a timer-off function will immediately go to a Volt-free, Watt-less state if a fault occurs. The differ-ence in behavior arises because in functional safety everything must be in a known state at all times, and that leads to this kind of difference in behav-ior. Controls engineers must get used to such differ-ences when working with an integrated functional safety system, according to Wadowick.

Free robotsRobots often are currently walled off for safety reasons, with perimeter guards and other technology protect-ing people from harm. An example can be seen in a project undertaken by Schmersal USA. The company has a customer that builds assembly equipment with automated tooling, robots and conveyors, says Mike DeRosier, engineering services manager.

He says this OEM wanted to improve the overall design of a machine while increasing productivity and maintaining current safety levels. To pull this off, a perimeter guard was added with both sliding and swing type doors for operator access. In this case, the first line of defense was not to allow an op-erator to reset the machine and put the robot into a running condition without everything being in line of sight due to a door remaining open.

The addition of various components and changes in guarding solved this problem. But, often stating the safety need is much easier than designing and implementing a guarding-based solution, DeRosier says. Instead, a better outcome can arise if what a ma-chine needs to do, how it operates and functions and how it interfaces with safety is looked at in totality.

“It may be a combination of a guarding solution

along with a change in function or process may also improve productivity, all with increased machine safety capabilities,” DeRosier says.

That sort of thinking beyond guarding may be critical to getting robots to work freely and safely alongside peo-ple. Stephan Stricker, a solutions architect with B&R In-dustrial Automation Group, says that implementing this highly desired capability will involve making changes in a robot’s behavior. Instead of building a big enough cage, a robot could be made safe by setting a safety lim-ited speed for every degree of motion, a safety limited position for every movement and a safe orientation, as a robot may have a mounted tool or laser that creates a hazard at an orientation-dependent distance (Figure 6).

Another key part of the solution is how to handle the situation when a machine is turned off. Stricker points out that the standard practice of moving a ro-bot to a safe home position is difficult to do when ma-chines and people freely intermingle. What’s more, the process of homing and then resuming operations adds time to a restart. A better answer is the use of a safety-rated encoder with some special capabilities.

“That allows you to turn off power but the encoder can still keep position,” Stricker says. “So, when you turn it back on, the encoder knows exactly where it is. The idea is you turn the machine off and turn it back on and you can pretty much start right away.”

When asked about other important trends and added capabilities, he says these include faster safety response times and deeper integration of safety. An

COLLABORATIONFigure 6: Enabling safe intermingling of people and robots will

require technology other than guarding, such as setting allowable

speed, reach and orientation for each degree of freedom.

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example of the former being modules with response times measured in microseconds, instead of the typ-ical milliseconds. This can be achieved by distrib-uting simple safety and other functions to modules on the machine. As for deeper integration, the use of software instead of hardware makes this easier.

Heading toward nothingNew and improved technology has made imple-menting safety easier and promises to add import-ant new capabilities. However, some things have not changed, nor are they likely to. For instance, meet-ing the appropriate safety standards is a big concern among machine users, according to Chris Marti, vice president of research, technology, safety and execu-tive education at the Metals Service Center Institute (MSCI). The Rolling Meadows, Illinois-based non-profit association serves the metals industry. It con-ducts an annual survey that tallies the rate of safety incidents and catalogs safety concerns.

“The metals industry has significantly better perfor-mance now, as opposed to a decade ago,” Marti says.

This data covers companies large and small, with the results somewhat fuzzy because the government definition of a recordable incident has evolved and expanded over the years. What have remained con-stant are the three main concerns that companies bring up in surveys. These are training, creating a safety culture and ensuring compliance.

David Sheer is vice president and general man-ager at  Steel Supply, also in Rolling Meadows, Il-linois. The value-added steel distributor has seen a drop in both incidents and near misses. Part of the improvement in safety has been the use of better technology, such as gloves and other personal pro-tective equipment that can better ensure fingers and other body parts suffer no harm. In addition, other technology improvements include saws with blades that freeze on contact with any unintended object, as well as better door safety devices and switches.

That technology has to be accompanied by train-

ing and the creation of a safety culture. That re-quires constant vigilance to make sure safeguards are in use, which, in turn, demands a commitment that the company’s management fulfills.

“I walk out on the plant a couple times a day and watch things,” Sheer says.

Discussing the trajectory of machine safety, Bev-corp’s Hendrickson notes that years ago there was little or no safety and so machine uptime was at a maximum, something that end users value. Then the adoption of standards and the implementation of safety protocols caused uptime to take a hit. Now, technology advances have made it possible to be both safer and more productive by providing, for ex-ample, better diagnostics. In turn, that has caused a reevaluation among end users of safety.

“There’s more user acceptance,” Hendrickson ex-plains.

Marti points to an industry goal of reducing the number of incidents to zero. The reasons for doing this are more than just monetary. “Safety is an ethi-cal and moral responsibility,” he says. “You want ev-erybody in your company to go home to their family at night, and you want them to go home in the same healthy condition they came to work in the morning.”

Marlin Steel is looking for equipment that keeps employees’ hands and fingers away from anything that will put them in harm’s way, says Greenblatt. “So, for example, we want guarding, lights, lasers, things of that nature to barricade our employees away from un-safe elements of the operation,” he says, echoing the desire to have everyone go home in one piece.

Sheer points out that anyone waging war against a 4,000-lb bundle of steel will always lose. Hence, there is a need for technology, training and the cre-ation of a safety culture. “It doesn’t have to be 4,000 lb. It can be 50 lb. You’re still going to break some-thing,” says Sheer. Improving safety and driving to-ward zero incidents can be good for any manufac-turer because danger doesn’t only come from big machines and large chunks of metal.

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Machine safety has improved exponentially over the past few decades. Automation and technol-ogy have played a key role in improving, but

there’s still work to be done. In December 2014, we conducted an electronic survey to identify usage and application trends of machine safety among the in-dustrial machine builders who read Control Design.

To decide which safety equipment their machines need, 56% of the respondents said they rely on ma-chine builders, 27% said end users choose, and 17% reported that system integrators decide. We also asked about builders’ biggest machine safety design head-aches, and almost half said it’s hard to know which standards and regulations to apply, while 37% said the worst problem is operators trying to defeat the safety system and 14% added that fully operational safety sys-tems impede their productivity.

“Necessity is the mother of invention,” says Rick Rice, applications specialist, engineering, at  Crest Foods  in Ashton, Illinois. “That old adage really has relevance when we are talking about safety and, specifically, ma-chine safety. In the past 20 years, manufacturers have become consciously aware of the fact that, while produc-tion is the bottom line, the real resource is the people. Some producers were brought to this realization of their own volition, while others became aware when OSHA succeeded in implementing procedures with fines and penalties for not adhering to this basic right to the pro-tection of life and limb. Regardless of the path to the light side, we are now, more or less, directly impacted by this shift in focus. I dare say that the machine-building industry hasn’t been the same since. While the first gen-eration of machine safety primarily involved surround-ing the machine in a physical barrier, the second wave has looked to technology to provide inspiration.”

Rice remembers the machines of the early 1990s. “Safety was in its infancy, and the quick way to compli-

ance meant putting up a fence and a switch on the door,” he recalls. “After a short period of time, machine builders and machine users alike realized that all these barriers made it harder to operate the machines with the same productivity. The human response to this was to disable the barriers or figure out creative ways of overcoming or cheating the system. Unfortunately, this meant dismem-berment and, for some poor souls, death. A new initiative must be made to protect the people better without im-peding the safe operation of the equipment.”

One of the biggest advancements in technology has come in the area of safety, says Rice. “Out of necessity, the industry has come up with ways to make machines safer, while allowing the machines to be not just pro-ductive, but more productive,” he explains. “The new-est initiatives seem to be more directed toward provid-ing better tools for the machine builder to use, in the name of safety. Safety PLCs are one way that safety has gotten easier for the machine builder, but sometimes we can do too much with the safety PLC. I prefer to keep the two systems separate and distinct but link them so that one can’t work without the other.”

The Crest Foods facility is focused on taking an ag-ing fleet of very capable packaging machinery and giv-ing it new life. “When one undertakes such an adven-ture, safety takes a major part in the decision-making process,” says Rice. “Safety devices can be very scary to our maintenance crew. Some of that comes from just the word ‘safety’ itself. People seem to immediately tense up when safety is mentioned. Our approach has been to simplify much of the safety initiative by implementing simple safety devices with as much built-in smarts as pos-sible. Sure, we use all the latest guidelines like Category 3 or 4 capabilities but we keep in mind the folks who will be troubleshooting the safety package when the system won’t restart. All of our doors utilize proximity RFID switches unless there is a need to physically ensure the

Where’s your safety now?Improvements in machine safety have come about due to changes in attitudes and technology

By Mike Bacidore

Trends in Technology

15

cessation of motion before the doors open. This means no physical parts to get fouled up with powder—believe me, we make a lot of powder. Our switches have two nor-mally closed contacts for the dual-channel safety circuit, but we have a normally open contact for PLC status, as well as indicators on each switch to visually draw the op-erator to the open door in addition to the message on the HMI. Same goes for our e-stops. Anything we can do to draw the user to the scene of the breach aides our ability to resume production more quickly.”

The human attitude needs the most change, says TJ McDermott, project manager at  Systems Interface  in Seattle. “Companies always say safety is their first pri-ority, so why do people continue to get hurt?  Machine guards get bypassed because what is under them needs

a lot more attention than the designer intended—jams happen. I’m still not at all convinced that the European method of legislating safety is the right way to go. Peo-ple still get hurt. At some point, the operators have to be responsible for their own actions and safety.” Bypassing a guard for ease of machine use should be grounds for firing and even possibly legal prosecution, he explains.

“As an integrator of robotic systems within packaging lines, we are working through conceptual differences in the risk assessment and grading process between the PMMI standard and the RIA standard,” says James Barry, director of engineering at Arpac in Schiller Park, Illinois.  “Another area that we are spending time on improvement is our capability to deliver 13849 ‘Perfor-mance Level’ documentation per customer demands.”

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For machine builders, there’s safety in numbers—specifically, the numbers represented by falling costs, increasing port count and greater connec-

tivity options of programmable safety solutions. Un-complicated setups may still best by served by tradi-tional, nonprogrammable and relatively simple safety relays, but ongoing improvements and greater flexi-bility have made programmable safety cost-effective for a wider array of situations.

For an example of the impact of programmable safety advances, consider a system from Intelligrated, a Mason, Ohio-based provider of intelligent auto-mated material handling solutions. Intelligrated built a mixed-load palletizing cell with specialized end-of-arm tooling that could handle multiple case sizes in a single pick, integrating advanced software, controls and vision technology to do so (Figure 1).

“Prior to programmable safety, achieving the func-tional and operational requirements of this kind of solution was costly and problematic,” says Matt Wicks, vice president of product development for manufacturing systems at Intelligrated.

Flexible and Safe Movement“Using programmable safety allows for more com-plex safety functionality to be implemented cost ef-fectively,” says Intelligrated’s Wicks. “An additional benefit is that this allows for quicker, less-costly changes to the safety system when there are changes in project scope like layout reconfiguration.”

For this particular system, Intelligrated used Rock-well Automation’s Allen-Bradley Compact Guard-Logix programmable automation controllers. To un-derstand why the flexibility added by programmable safety is important, it helps to realize that an automated palletizing system may consist of multiple robot cells,

Programmable safety cuts costs and adds capabilitiesOngoing improvements and flexibility make programmable safety affordable

By Hank Hogan

MIXED LOADSFigure 1: A mixed-load palletizer with specialized end-

of-arm tooling can handle multiple case sizes in a single

pick by integrating advanced software, controls and a

programmable safety controller.

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Trends in Technology

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each with its own point of entry, as well as a discharge transfer system of the finished pallet of material. The final product may go through a stack-and-wrap solution that readies the pallet for shipment.

Each piece of equipment has a potential safe-ty-level interaction with others in the system. Pro-grammable safety can define this interaction, elim-inating the time spent on complex safety circuit wiring. Consequently, equipment providers and in-tegrators can make functional changes as needed while minimizing any implementation risk.

That flexibility can be important to end users, Wicks says. “It also reduces risk for our end custom-ers as they may not recognize operational impacts until the system has been implemented,” he says.

Intelligrated has used Rockwell Automation pro-grammable safety solutions for years. But for simple setups such technology may be more costly than an approach based upon more traditional controllers and safety relays. Generally, programmable safety makes sense in situations where there are more in-teractions with other types of equipment and if there are more specialized or unique cases that must be handled, Wicks says. All applications with a PLC or similarly capable controller will need some sort of safety solution, says Tim Roback, marketing man-ager for safety systems at Rockwell Automation. He adds that an integrated solution that combines con-trol and safety into one programmable product en-ables optimization because there is information as-sociated with a safety event. Data such as how often a fault occurs or an e-stop activates can be important in devising ways to avoid such halts to production. This data also can help to minimize downtime by pinpointing what caused a fault and why.

Then combined with the right choices early in the design cycle, such programmability can help to improve both safety and productivity. For exam-ple, a machine can be zoned into different sections, with staging areas between the zones. As a result, a problem in one area and the opening up of an inter-

locked door may not mean that the entire manufac-turing process has to stop.

“You can continue to produce product in one zone while you clear a jam in another,” Roback says. A somewhat similar benefit is that with programma-ble safety a machine can come to a controlled stop, he adds. For instance, a bottle-filling machine may halt after the current batch of bottles are completely filled, which makes starting up after fixing a fault faster and smoother. Such cases illustrate that pro-grammable safety can make restarting a machine easier and quicker than is possible with simpler and less flexible technology.

Safety and SavingsAnother example of the use of and benefits from programmable safety comes from system integrator and tooling manufacturer Five Lakes Automation of Novi, Michigan. Five Lakes Automation works with Tier 1 automotive suppliers, with a focus on weld-ing, riveting or other joining applications, says Proj-ect Manager David Jones.

In one case, there was an operator station to which a robot was being added in an assembly line for a major automotive manufacturer. The robot had sev-en-axis movement, with the entire robot base trav-eling toward and away from the operator. The use of a safety PLC improved the flexibility of the solu-tion and dropped its cost. The alternative was a large complete panel with an array of safety relays that would have taken up a considerable amount of space and consumed quite a bit of design and installation time.

In contrast, the programmable solution that was implemented involved a single small junction box and much less design time. What’s more, adding a safety function at some point later would be as sim-ple as wiring a device to available inputs on the safety controller. Accomplishing the same upgrade with a safety relay-based approach would not be as straightforward.

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“We’d have to find panel space and bring wir-ing in,” explains Jones. “It takes something that we could probably accomplish in a couple days using programmable safety to a couple weeks.”

Simple setups and machines do not generally ben-efit enough to offset the extra cost of a safety PLC, Jones notes. Examples might be a single rivet tool or another machine dedicated to a single task. Typi-cally, these tools have very little in the way of safety requirements. Also, they often are single enclosure tools located within 10 ft of any safety systems.

However, even for some relatively simple ma-chines, savings in design time and reductions in startup debugging may make programmable safety cost-effective, says Jones. That’s one reason why Five Lakes Automation steers customers to safety PLCs from Rockwell Automation and Pilz. “We recom-mend these options to our customers over hardwired applications due to their flexibility in design changes and the reduced time in startup,” Jones says.

One advantage of a programmable safety solu-

tion is the more-extensive diagnostics it offers, says Dino Mariuz, engineering manager at Pilz. The ad-ditional information thus produced will add value and may overcome any price added, even for simple setups.

A growing trend is to make programmable safety systems compatible with Ethernet-based or other network communication protocols. One result will be an expansion into wireless platforms, explains Mariuz.

With regard to advice about programmable safety, Mariuz offers two items. One is that being able to program a PLC doesn’t necessarily translate into be-ing knowledgeable about safety. Thus, accepted tech-niques and safety standards must be followed. The second is that the safety of a solution, programmable or not, must be verified by control engineers or end users with the appropriate qualifications (Figure 2).

“Once the system is installed, they need to val-idate the safety system to ensure that the system meets the safety specification,” Mariuz says.

UNDER MANAGEMENT

Figure 2: Wilson Transformer uses a programmable safety controller to manage control components and safety systems,

an approach that allows for flexibility with multiple network communication platforms.

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Density, Connectivity and LifecycleProgrammable safety offers benefits that aren’t possi-ble otherwise, says Matt Dodds, safety product mar-keting manager at Omron Automation & Safety. For instance, programmable safety can enable a scalable solution, which means that customers can poten-tially master one style of programming and hardware that moves up with them from stand-alone machines to entire production lines.

There also can be a productivity payoff. With pro-grammable safety, there can be an emergency stop and a separate protective, or Cat. 2. stop. The latter brings things to a halt in a controlled fashion and holds everything in place under power. Doing so leaves actuators energized, preserving position and other information needed for a restart.

Today a compact safety controller can replace three 6-ft panels full of safety relays and associated wiring, reducing space requirements twenty-fold, says Dodds. An added advantage is that reliability can be increased because hardwired relays that wear out are eliminated. While there will always be a need for safety relays and associated equipment, ongoing cost reductions have dropped the point in application complexity at which programmable safety makes sense.

“Once you move into systems requiring more than three sets of inputs, then compact safety controllers start to become cost-effective, and they give you the added convenience of being able to be monitored over networks by a PLC, HMI or other similar de-vice,” Dodds says.

The trend is toward more connectivity and more compact programmable safety devices, says Martin Lalonde, applications engineer at  Wieland Electric. The second of these shows up in increased density, such as a greater number of ports and with more of these configurable. For instance, some recent pro-grammable safety products have 24 I/O ports in their base configuration while their predecessors had none. As for connectivity, that typically involves the addition of Ethernet, a capability that brings various benefits.

“That Ethernet port can be used for remote pro-gramming, so if somebody is doing remote support maintenance through a VPN router, for example, that’s something that would be fantastic to have,” Lalonde says. “Nobody wants to have to fly over to fix a non-issue or do a simple change to a program that could be done remotely. So you can save a lot of time and effort and money.”

Perhaps the biggest reason why safety systems of any type are defeated is that those designing the safeguards don’t take into account how machines will be used. Maintenance personnel, for instance, may need to bypass some safety interlocks while working on a machine. Programmable safety can help to minimize any hazard by allowing for the use of a maintenance mode. Another specialized mode might involve starting a machine, particularly if during such times greater access is needed than is the case during full-blown production.

“You have to look at safety as a lifecycle approach,” says Rockwell Automation’s Roback. That lifecycle in-cludes the design of the machine, its various modes of use on the factory floor, any upgrades or changes that it may undergo and finally its disposal. Because of its flexibility, programmable safety offers a way poten-tially to better meet these diverse requirements.

Finally, whether or not newer technology or the more traditional approach should be used will de-pend upon the particulars of a situation. Machine builders need to evaluate their equipment and ap-plications and then do the math to determine the ROI that comes from leveraging the greater capa-bilities offered by programmable safety. In those re-turn-on-investment calculations, it’s vital that every-thing be considered, including any hidden costs, as well as unrecognized benefits. Doing a complete evaluation helps when comparing programmable to traditional safety solutions.

“Do your homework and understand the pros and cons to implementing programmable safety,” advises Intelligrated’s Wicks.

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What will the next generation of manufacturing workers look like? One thing is certain. These individuals will be able to work with robots —

capable of programming them, as well as allowed to interact with them, side by side.

Ntxuzone Yang and Luede Yang are cousins. The two are students at the University of Arkansas — Fort Smith (UAFS). I met them in the ABB Robotics lab when I toured it as part of the Baldor Publishers Tour in November 2014. The lab’s robots comprise mostly ABB’s IRB 120 model, some donated and the rest dis-counted. The Yangs are part of the new wave of in-dustrial technology and automation, thanks largely to their participation in the UAFS program. And robot-ics will play an equally important role, especially now with the introduction of collaborative robots.

“We see several cases where robots designed for power- and force-limiting applications, such as ABB YuMi, Universal, Baxter and Kuka LBR iiwa, are called ‘collaborative robots,’” explains Pat Davison, di-rector of standards development at Robotic Industries Association in Ann Arbor, Michigan. “This is a bit of a misnomer. It would be more appropriate to call these ‘power- and force-limiting robots.’ Furthermore, any collaborative situation is going to depend on the ap-

plication, or what the robot is doing, as a condition of determining whether perimeter guarding will be nec-essary. I understand these concepts make the collabo-rative robot discussion a bit more complicated, but not being explicit in these clarifications seems to create confusion or the potential for misapplication, which is something the standards development community hopes to avoid.”

Ntxuzone Yang and Luede Yang are cousins and

students working with ABB Robotics in the program at

University of Arkansas — Fort Smith.

Manufacturing workers - the next generationWould Our Future Workers be Robots or Humans?

By Mike Bacidore

Trends in Technology

22

Davison warns companies against wanting to de-ploy a collaborative robot to avoid devoting capital or floor space for machine guarding. “We see this as putting the cart before the horse,” he explains. “A more appropriate deployment from the stan-dards development perspective is that a company identifies an application it wishes to automate and, through a risk assessment, determines that deploy-ing a collaborative robot application would not pose an unacceptable risk to personnel and proceeds with designing the cell with an appropriate level of safeguarding.”

Human-robot collaboration will only become more important, predicts Per Vegard Nerseth, global head of the robotics business at ABB. “To meet the flexible and agile production needs required in the consumer electronics industry, and increasingly in other market sectors, ABB has developed YuMi, a dual-arm small parts assembly robot that can collab-orate, side by side, with humans in a normal man-ufacturing environment enabling companies to get the best out of both humans and robots, together,” he explains. “The intrinsically safe design of the ro-bot with soft padded dual arms combined with in-novative force-sensing technology ensures the com-plete safety of human co-workers. Its ‘intrinsically safe’ rating means it can work alongside humans without posing any risk whatsoever to their safety. We expect that it will be mostly employed in the consumer electronics industries and will focus our initial efforts there, but clearly it has potential be-yond those industries.”

Continued development of safety standards in the United States and internationally are helping to en-able the evolution of these applications in new in-dustries. “ISO 10218 and ANSI/RIA R15.06-2012 set forth four different modes of collaborative op-eration,” explains Davison. “These different modes can use a variety of technology to achieve the criteria in the standard. The standard sets the requirements for the robots or robotic applications, but it doesn’t specify which technologies must be used. For safe-ty-rated monitored stop and hand guiding, improve-ments in controls technology is the enabling factor. For speed and separation monitoring, area scanners help to identify the locations of potential hazards or obstacles, and the controls technology ensures the ro-bot reacts appropriately. For power- and force-limit-ing applications, technologies being used include the controls technology and mechanical actuators that allow the joints to give in contact situations.

Additionally, larger surface areas, elimination of pinch points by offsetting axes, padding and other design factors can all contribute.”

A new technical specification addresses the po-tential for incidental contact between robots and humans. “We had been awaiting the results of the study taking place at the University of Mainz regard-ing the onset of pain at various body regions,” ex-plains Davison. “The study is now complete, and the working group has an agreement in principle on how the study results will be used in setting guidance on power and force limits. I am optimistic that the TS will be published in 2015.”

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Machine safety is moving from the outside to the inside. Traditional guarding and other protec-tions are being replaced or at least supplemented

by intelligent, automated safety PLCs, better-coordi-nated networks and other supporting devices.

Integrated into machines at their earliest design and assembly stages, these safety components and

software can establish safe zones, guarantee safe speeds and non-injurious motion, and allow oper-ators to stay safe even as they interact more closely with their machines. Likewise, domestic and inter-national machine safety standards are harmonizing to better help builders and users apply common, uni-form safety components (Figure 1).

Machine safety is elemental for new automated systemsOnce an external add-on after construction, safety is now a fundamental, unifying building

block in modern machine design

By Jim Montague

STANDARDS ORGANIZATIONS STANDARDS DESCRIPTIONS USA EU COMMENTS

International Organization for Standardization (www.iso.org)

ISO 13849-1, functional safety (FS), application-specific (AS), uses performance levels (PLs) ISO 13849-2, FS, validation ISO 12100, FS, risk assessment

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Can use Safety Integrity Software Tool for the Evaluation of Machine Applications (SISTEMA)

International Electrotechnical Commission

(www.iec.ch)

IEC 61508, generic safety standard

IEC 62061, FS, AS, uses SIL categories

IEC 61511, process safety standard

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softwa/sistema/index.jsp

U.S. Occupational Safety

and Health Administration (www.osha.gov)

OSHA 29 CFR 1910, Subpart O, machinery and

machine guarding safety

OSHA 29 CFR 1910.147, control of hazardous energy

(lockout/tagout)

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Safety products and solutions are tested and

certified by national, recognized testing

labs (NRTLs)

American National Standards Institute

(www.ansi.org)

ANSI B11 Series, 2007-2010 X - To be followed for application-specific standards

National Fire Protection Association (www.

nfpa.org)

NFPA 79, 2012, machine safety

NFPA 85, 2011, burner management

NFPA 86, 2011, burner management

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Compliance required; wireless and drives safety

allowed

Underwriters Laboratories

(www.ul.com)

UL NRGF covers ANSI, UL 508, 1998,

NFPA79 and IEC 61508.

New UL FS mark is similar to TUV

X - New UL functional safety mark and recognition

same as TUV certificate

Robotics Industries Association

(www.robotics.org)

ANSI, RIA R15.06-2012,

ANSI, RIA, ISO 10218-1-2007

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Required for all robotic, machine-safety

applications

Canadian Standards Association (www.

csagroup.org)

CSA Z434, safety requirements for robots and robotic

systems

- - Required for OEMs shipping machines to Canada

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SAFETY STANDARDS SNAPSHOTFigure 1: Many local, domestic and international machine safety standards have been harmonizing in recent years, but it’s still crucial to investigate which apply to machine builders and their users based on location and particular industrial function and application.

Trends in Technology

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“The Occupational Safety and Health Adminis-tration’s regulations have been around for more than 40 years, so most companies have some safeguards in place on their machinery, but most of these safe-guards are expensive, physical barriers that most likely limit productivity,” says Jeff Winter, safety busi-ness manager for North America at Grantek Systems Integration (www.grantek.com) in Oak Brook, Ill.

“However, recent changes in international safety standards have plowed the road for the rest of the world to integrate safety technology into standard automation functionality. Compared to conventional guarding, we now can reduce hardware costs, simplify control archi-tecture, reduce design and engineering time, increase diagnostics and ultimately make a safer work environ-ment. So even if a machine is conventionally safe, over-hauling its safety system could improve its safety and overall equipment effectiveness (OEE).”

For instance,  Sandvik Materials Technology  is a worldwide developer and producer of advanced stain-less steels, alloys, titanium and high-performance materials, and its cold-rolling mill in Sandviken, Sweden, has been a key part of its precision-strip-steel production line since it was built in the 1930s. The mill is 20 meters long and processes high-carbon steel and stainless grades, and produces strips up to 400-mm wide and 1 to 6 mm thick (Figure 2). 

Understandably, the mill’s mechanical, electronic and control systems were renovated over the years, and Sandvik recently added servomotors, standard PLCs and touchscreen HMIs from  ABB. However, the company’s latest effort to migrate its hard-wired safety systems to zoned safety guarding required it to switch out even more equipment. “We needed to expand the plant and production line’s safety, so we decided to install a new control system with a safety central processing unit (CPU) on the cold-rolling mill, but this also meant replacing its safety-related electronics and controls and adding some automatic functions too,” says Torbjörn Pettersson, Sandvik’s engineering development specialist.

Put risks into zones  To find the most appropriate safety and control solu-tion for their cold-rolling mill, Sandvik’s engineer-ing and production staffs conducted a risk assessment (RA) in accordance with Swedish directive 2006:4, användning av arbetsutrustning (use of work equip-ment), and determined the mill needed six different safety zones based on its inlet parts, rolling and re-moval parts sections.

“It’s important to have a risk assessment to start with,”Pettersson explains. “After that, you must work

COLD ROLL WITH CAREFigure 2: Sandvik Material Technology recently added

a safety PLC with dual-processor CPU, Profisafe

networking and safety I/O channels to its cold-rolling

mill in Sandviken, Sweden. This enabled six safety zones

and safe speeds in the mill’s inlet, rolling and output

sections, and improved strip-steel processing efficiency.

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through function descriptions and operating instruc-tions. For us, it took a lot of time to find solutions for our new safety functions so they would be safe and productive. Once the instructions are finished, it’s much easier to write the safety program. This is important because it can take lot of time to do a new RA and change safety functions and programs during commissioning if the initial solutions don’t work out. It’s also important to separate safety and the non-safety programs in the controls. This will make it easier to commission and test the safety functions, and these systems will be much easier to maintain because a clear, readable program will minimize the risk of any misunderstandings.”

Sandvik also adopted ABB’s safety PLC with Profis-afe network architecture via Profinet communications protocol to independently control the six safety zones. The new dual-processor safety CPU module and the safety I/O channels are integrated alongside the mill’s existing PLC, which controls six dc and ac drives and motors. The dc motors drive the main steel belt and rollers, while the ac motors adjust roller position to achieve desired pressure during strip-steel processing.

This new arrangement with the safety PLC allows parts of the mill to remain operational while an op-erator gains safe access to some other zone, where safety is assured by disabling power. About 50 safety PLC I/O channels also link to gate switches, light curtains and E-stop buttons. The I/O points also monitor pressure switches to sense that hydraulic power is disabled for maintenance.

“Establishing safe zones inside machines allows power to be brought to a safe level without shutting down and having to resynchronize the entire ma-chine,” says Gary Thrall, senior product support en-gineer and TÜV-certified functional safety engineer at Bosch Rexroth (www.boschrexroth-us.com). “Sim-ilarly, safe-direction functions can be set up in safety zones, so all power won’t have to be removed when operators are loading or unloading materials. This can save 10% on many production cycle times.”

Simpler standards, proactive mindsetsTo conduct thorough, uniform RAs and achieve the greatest practical safety at the design stage, there are a variety of domestic, regional and international machine-safety standards that builders can use. Most significantly, the ISO 13849 standard pushes machine builders and users to move from comply-ing with traditional safety categories to instead cal-culating and achieving performance levels. 

Grantek’s Winter adds that, “Risk assessments are like resumes. Everyone has one, but they all look a little different. The important part is they all achieve the same basic purpose and contain the same basic information. For that reason, it’s important to use an RA and risk reduction process that works for your or-ganization. The first and most important step is to base your process on nationally recognized, con-sensus standards, such as ISO 12100, ANSI B11.0 or other industry-specific standards. The second and most challenging step is to develop a procedure and rules to support the process to ensure you have con-sistent results from one RA to another.”

Winter reports that deciding which safety stan-dards to follow begins with the location of the end user’s manufacturing facility, and then OEMs, inte-grators, contractors and everyone else follows suit. “In the U.S., you start with federal and state OSHA regulations, and then use standards it has incorpo-rated through reference, which are primarily Amer-ican National Standards Institute and National Fire Protection Assn.”Winter says that because recently revised ANSI standards are starting to harmonize with International Organization for Standardiza-tion and International Electrotechnical Commis-sion  standards, it’s important to be aware of their contents too. In Europe, this burden is on machine designers and builders.

“Because U.S. and Canadian machine builders and system integrators are at the mercy of clients’ re-quests, they’ll follow national or internal standards most of the time,”Winter continues. “However, it’s

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not uncommon for them to also embrace unique, company-specific, homemade requirements. Europe has a much more restrictive approach, and to meet the ‘presumption of conformity’ of the EHS require-ments in the Machinery Directive 2006/42/EC, you must follow one or more of the hundreds of harmo-nized standards listed in the European Union’s of-ficial journal. In lieu of customer specifications, it’s highly advisable to have an internal specification of minimum safety requirements and to list the stan-dards chosen to demonstrate compliance.”

To help machine builders learn and perform ISO 13849-1’s calculations, the free “Safety Integrity Software Tool for the Evaluation of Machine Ap-plications” (SISTEMA) is offered by the German Social Accident Insurance organization’s  Institute for Occupational Safety and Health. The tool pro-vides comprehensive support in evaluating safety in the context of ISO 13849-1.

Safe motion, new toolsBesides setting up safe operating zones, the most im-portant benefit of integrating safety PLCs into ma-chine designs is establishing safe direction, speed and other motion that won’t allow operators to be injured.  

Back at Sandvik’s cold-rolling mill, the safety PLC provides safe speed control, which ensures that hands or fingers can’t be trapped between the mill’s belt and rollers. The safety PLC also allows Sand-vik’s engineers to use floating-point numbers that simplify safety programming required for tasks on the mill, such as calculating speed. Programming was further simplified by ABB’s integrated PLC de-velopment tool, which supports safety PLC program-ming in its CoDeSys-based integrated development

environment and supports the PLCopen Safety Li-brary. ABB also provided its own safety code ana-lyzer tool, which verifies safety programming rules.

“Establishing the zones and using the safety PLC improve the cold-rolling mill’s safety, but they also aided our efficiency because we designed new functions for threading the strip to separate opera-tor and machine, and this enabled the mill to run more effectively and more safely,” Pettersson says.

CAUTION IN CAR ASSEMBLY CELLS Figure 3: Audi’s new A3 body assembly line includes 800

robots in 130 cells which are managed by cell operator control

units that have an industrial PC for programming, diagnostics

and visualization, and use safety PLCs, network switches and

safety I/O modules installed in a lower unit for easy access.

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To help more users gain these safety capabilities, some developers take them beyond the usual safety PLC. For instance, B&R Industrial Automation just introduced its safety PLC that comes in the form of an I/O module, while its “soft” counterpart is a vir-tual, purely software-based version that can run on other hardware devices if needed. The PLC provides programmable and network safety to machines that don’t need a large complex safety system, according to Corey Morton, B&R’s technology solutions direc-tor. “Safe motion and safe-limited speeds and posi-tioning can produce big productivity gains because users can maintain existing power, positions and axes in their machines,”he adds. “Both approaches can do these jobs.”

Similarly, as a longtime practitioner of PC-based control,Beckhoff Automation  includes its TÜV-ap-proved Functional Safety over EtherCAT (FSOE) capabilities in its existing control systems, which achieve ISO 13849 Level E and SIL 3 ratings. “ISO 13849 went into effect in January 2012, so machine safety’s been at the forefront of everyone’s thoughts since then, and their awareness is growing quickly,” says Tony Rigoni, regional sales manager for northern California and safety expert at Beckhoff Automation.

Up into auto plantsOf course, once builders and users get a taste of de-signing and integrating intelligent safety into ma-chines, many want to deploy it in larger production lines and facilities. 

For example,  Audi  recently redesigned its A3 model and built a two-level production building at its plant in Ingolstadt, Germany, for its new body assembly line, which operates up to 800 robots in

130 work cells (Figure 3). The A3’s lightweight, third-generation body needed a higher-perfor-mance production line that was f lexible, reconfig-urable and able to deliver more sophisticated di-agnostics in the cells and on conveyors, so Audi’s engineers selected Profisafe and Profinet network-ing and safety PLCs from Phoenix Contact.

The safety PLC is unusual because it consists of two independent controllers. One is a standard, programmable, IEC 61131-compliant PLC, and the second is a SIL 3-rated safety control system. While one platform is responsible for standard applications and Profinet communications, the other prepares Profisafe telegrams and performs its safety application. This means the PLC executes its standard system and safety programs in parallel, but separate from each other, which ensures inde-pendent control and timing for each function and keeps cycle times short for the control and safety programs. Short software cycle times are crucial to maintain optimal production cycle times by the various work steps in Audi’s cells. Also, the control of individual command devices such as robots or frequency converters requires a handshake tech-nique, which means added PLC cycles are needed. However, Audi’s engineers report that this solution helped reduce PLC cycle times to an average of 12 milliseconds, which means the cycle time of the larger cells could be reduced by up to one second.

The controls are programmed with two inter-connected tools. An engineering tool configures the Profinet system hardware and creates the stan-dard IEC 61131 application, and the safety PLC’s software handles the safety PLC. Safety functions of each cell, including emergency stops, protective

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door contacts, guards in loading and infeed areas, and safety-related robot and drive functions, are pro-grammed in the safety controller. Also, once the PLC’s programs are validated, they’re password-pro-tected to prevent unauthorized changes, while ac-cess to the PLC’s safety components also can be password-protected for added safety during start-ups.   

Similarly, Kia Motors  (KMC) builds three SUV models, which make up more than half of the al-most 230,000 vehicles it produces each year, at its Kia Motor Slovakia (KMS) division in Teplika nad Váhom. The body shop at KMS and its body-com-plete (BC) line assemble all moving parts with manual handling performed by 20 workers and equipment managed by controllers and software from Rockwell Automation.

Unfortunately, the BC line also suffered frequent breakdowns that decreased productivity and some-times caused the entire line to stop.

KMS reports its BC line had been us-ing  Sick’s  afety relays and safety scanners, which it says had complicated wiring and long conductor routing from safety devices to relays in the main cabinet and lacked a bypass function from the scan-ners. Though traditional relays long have prevented hazardous interactions between operators and ma-chines, KMS adds its safety relays also caused many small line stops, and often made it hard to identify why and where they were happening.   

Consequently, KMS decided to add Allen-Bradley safety PLCs to its ControlLogix control system. The BC line added remote safety I/O modules and con-nected to the plant’s EtherNet/IP network, which al-lowed visualization of safety conditions, alarms, emer-gency events and programming developed for its HMIs.

 Previously, if a person entered a cell, or if a device failed during production, the entire line stopped, and each area had to be checked to find the source of the fault. Now, the BC line is divided into five zones, each with a cabinet with Safety Point I/O components and only two or three meters of wiring. Each safety I/O is connected to the safety PLC via EtherNet/IP. So when the BC line is interrupted, only the relevant zone is stopped, which indicates its location and enables quick recovery while other zones remain operational.

“With the ability to identify failures and solve problems quickly, we’ve increased productivity by reducing safety breakdown time up to 70%,”ex-plains Ondrey Vasek, body shop maintenance man-ager at KMS. “The body-complete line is easier to maintain and makes our lives easier.”  

“It’s important to have a risk assessment to start with. After that, you must take lot of time to work through function descriptions and operations instructions. For us, it took lot of time to find solutions for our new safety functions, so they would be safe and productive.”

“In lieu of customer specifications, it’s highly ad-visable to have an internal specification of minimum safety requirements and list the standards chosen to demonstrate compliance. The more engineers that work on a safety project, the more important it is to have a set of design requirements, specifications and templates to ensure everyone is interpreting the stan-dards in the same way.”

“The best thing about machine safety getting auto-mated is that it opens up the world to more engineer-ing creativity, and the standards give engineers the ability to rate, define and validate safety performance for their users.”

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When you’ve got to stop, you’ve got to stop. For machine builders, that’s usually a job for safety switches. They allow safe access to

dangerous machines by putting systems in a harm-less state, which could mean cutting off power com-pletely. In selecting a safety switch, it’s important to keep in mind frequency and function, according to Roberta Nelson Shea, global marketing manager for Rockwell Automation. For something that needs to be opened only once a year, the best solution likely is to use simple guards, such as by completely encas-ing the area. More frequent access has to be easier. It’s when access is frequent, but not constant that an interlocking safety switch comes into play.

“You expect somebody needs to get in there at least once a day, possibly more frequently,” Shea says. “That’s when we would make use of some sort of interlocking switch for that guard that would be connected with the machine control system, so that when you opened the guard, the machine would come to a safe state.”

The simplest, often lowest-cost and most op-erationally robust solution is a tongue interlock-ing switch, Shea indicates. These switches have a tongue actuator on one door that forces apart con-tacts in a switch attached to another door. Pulling out the tongue signals that the door has opened, and the machine should be stopped. 

As for function, trapped key systems are best for sequential access, which requires going through a series to steps to get to the area in question, accord-

ing to Shea. Trapped key systems also could be the method of choice in a hazardous location because some require no voltage to operate. However, to min-imize any danger, the interlocking typically takes place outside of the hazardous location itself.

In different operating conditions, guard-locking switches are likely best. For instance, sometimes machines have a long run-down time, such as when a spinning or otherwise moving system takes some time to come to a halt. Consequently, there has to be some way to keep the door or other access points closed. This can be done through a switch that does not release a guard until certain conditions, such as a long enough period of time, have been met. Guard-locking switches also can handle cases in which a chance for serious bodily injury exists, and power is lost to a machine.

“You have to apply power to have it unlock. So, therefore, if there is loss of power, the guard is locked,” Shea says.

In still other circumstances, non-contact safety in-terlocks are best. There are several technology choices, such as an array of coded magnets or a radio frequency identification (RFID) reader and tag. No matter the technology, such switches have built-in safeguards that prevent an easy defeat of the safety function.

“For example, if you have an RFID system, you can have a unique code, so that actuator will only work with that sensor,” says Matt Dodds, product manager of safety switches, relays, controllers, edges and mats at Omron Automation.

Consider the need for safety switchesNo matter what type of switch is used, it’s important to recognize and account for the needs

of engineering staff, maintenance personnel and operators to access a machine for upkeep

and cleaning

By Hank Hogan

Back to the Basics

30

Speaking of non-contact safety switches, Dodds adds, “These are good in wet environments because there are no exposed moving mechanical parts to be interfered with.”

“It’s the frequency of access that’s the first factor in de-ciding which safety switch is best for a given situation. ”

Other advantages of non-contact safety switches are that they’re small, lightweight and easy to mount. A disadvantage is that actuation might be problem-atic, particularly for some of the more inexpensive switches, according to Dodds. 

No matter what type of switch is used, it’s import-ant to recognize and account for the needs of engi-neering staff, maintenance personnel and operators to access a machine for upkeep and cleaning. Con-sider a setup with an interlocking switch that imme-diately kills power to a machine if a door is opened. When that happens, the result is a system on which maintenance technicians can’t run diagnostics. Given that situation, maintenance has to bypass the safeguard to do its job, so a supposedly safe setup is actually not, Dodds points out. “The safety needs to be engineered into the system, so it’s integral to the process and done at the onset of the machine design, not after the fact,” he says.

For those times when nothing less than a com-plete power shut-off will do, consider an industrial safety switch. Built with a pull lever or handle, these are part of the standard electrical portfolio and have a basic function, according to Terri Vallera, senior product manager for safety switches at GE Industrial Solutions. “The main reason to use a safety switch is as a means to disconnect power to whatever device or machine you’re feeding,” she says.

Placed on every piece of piece of equipment in a facility, a safety switch should be easily visible and

within 50 feet of the device it supports, Vallera adds. By cutting power, these switches allow servicing of machinery without risk of electrical injury and also provide an emergency shut-off. 

The switches themselves are simple in opera-tion, with a quick-make/quick-break technology that hasn’t changed significantly in years. When contacts are closed, power flows. Power stops when contacts are open, either by someone moving a handle or, if the switch is fused, by an overcurrent situation. 

Because such switches must meet a machine’s re-quirements, the most important consideration is the needed voltage and amperage, or the horsepower. Af-ter that, the next consideration is the type of enclo-sure around the switch. Indoor applications in fairly clean environments can get by with a NEMA 1-rated enclosure, whose main job to protect against inadver-tent contact. Switches located outdoors should go into a weather-protecting NEMA 3R enclosure. Most plant floors probably will have a dust-tight NEMA 5/12 or a NEMA 4X enclosure, with the latter corrosion-resis-tant and capable of withstanding a washdown.

If it’s important to keep a machine fault isolated from other devices upstream, then a fusible switch should be used, Vallera indicates. If a motor or an-other component with a rush of starting current is in-volved, it might be best to go with a time-delay fuse to permit additional current draw during start-up.

No matter what safeguarding technology is cho-sen, a switch or other component mishap or break-down can occur. Thus, ready product availability is important. Otherwise, what might be stopped could be more than a machine.

As Vallera says, “Factories and even OEM applica-tions can be dependent on local availability to keep their operations running smoothly.”

31

Safety first is a common mantra. But at what cost?Now this “cost” is relative. Bill C-35 is Canadian legislation that puts employees first by criminally charging owners and managers for workplace safety violations and employee lost-time injuries. Some of them have gone to jail as the result of the death of an employee due to the lack of safety consider-ations.

The Canadian automation magazine of record is Manufacturing Automation (MA). It does a good job of covering Canadian as well as international issues. It did a piece on safety a couple of years ago. I re-read this piece (yes, I’m a pack rat), and dis-covered some “odd” statements. For example, a ma-chine builder that employs machine safety proba-bly would have higher throughput, higher ROI and higher profitability from that machine process.

So one cost of not doing safety is possible jail time; another is the cost of not implementing safety as part of the machine design. Control Design reg-ularly has written that machine builders in the U.S. see the same patterns.

That leads us to another cost, which is the phys-ical cost of the hardware, additional installation time, start-up time and training.

I developed a project with five PLCs and six safety PLCs, all networked together. I devised a way of coordinating the control and safety, so that if an E-stop was hit at position A, then only “X” would happen. An E-stop at position B would allow only “Y” to happen. Segregation of control and safety outcomes was paramount.

This project did not give the user additional throughput time or profitability as a result of the safety solution used. It was strictly a CYA design—the customer’s, not mine.

The real moneyball problem comes when a light curtain or a gate switch is triggered, after which the user has to reset the system. Due to the complexity of the operation, a certain sequence has to be fol-lowed to get the systems back on line, and that takes time and resources. This is a money loser, not a money winner. But it has to be done, and the added complexity of using different vendors for safety and control add to the confusion, since one doesn’t talk to the other except through I/O.

Fast-forward to the present, when I did a software review for MA on Rockwell Automation’s Micro800 line of PLCs. The software is called Components Workbench, and it’s free. It is an IEC 61131 editor

What’s your machine safety cost?How much cost is really incurred when implementing a safety strategy on a machine?

By Jeremy Pollard

Back to the Basics

32

that aggregates code for various bits of hardware, such as HMI, drives and safety appliances.

Safety relays and safety PLCs have come a long way, though the implementation isn’t cheap. But at least having a common software platform aids in the development of and in the construction of a safety strategy.

In the application I noted earlier, the safety ven-dor is Pilz Automation Safety. It has a great prod-uct, and I also reviewed the new version 9.x of its software. It blows Components Workbench out of the water with presentation and functionality. It isn’t free, but it’s very affordable.

The learning curve is not steep, but it might not play well with others, even though it has an Ether-net interface, because it can’t communicate over the network directly. Thus the complexity.

“So one cost of not doing safety is possible jail time; another is the cost of not implementing safety as part of the machine design.”

So how much cost really is incurred when im-plementing a safety strategy on a machine? Stan-dard components such as E-stops are required. Are safety PLCs specified in the design documents? Ac-cording to a safety representative, the answer is no.

It’s not that the companies don’t care about their employees’ safety. It’s all about competing with sup-pliers that don’t include a safety strategy. If the cus-tomer is a utility, then cost is everything. If it’s a packaging customer, while cost is still a factor, you as an OEM might expect the end user to implement his own strategy, since your machine might be part of a larger system. Then the end user is responsible for increasing his own throughput due to safety.

While it’s really hard to say how safety helps with the bottom line, we know that it affects the top line regardless of how complex the strategy is.

We also know that costs are relative. How much are you willing to spend, invest or save with a strat-egy that has to be a winner, not a loser?

33

I f your company manufactures machinery that has potential hazards associated with its transportation, installation, use, maintenance, decommissioning

and/or disposal, you most likely have a very strong need to create effective product safety labels. This task must be done right. Simply put, the stakes are too high for this job to be done incorrectly. People’s lives and your company’s financial well-being are on the line.

From a vantage point of playing a role on stan-dards committees in this field over the past 25 years, I’ve seen how safety labels can help or hin-der those activities. While I’m not speaking for the standards committees on which I serve, I’ve noted first-hand two important outcomes:

1. If properly designed, safety labels can reduce accidents dramatically. This not only improves a product’s overall safety record but adds to a company’s bottom line by reducing product li-ability litigation and insurance costs.

2. If poorly designed, then needed safety commu-nication does not take place, and this can lead to accidents that cause injuries. When such ac-cidents happen, companies spend hundreds of thousands (if not millions) of dollars settling or fighting lawsuits because their products lacked adequate warnings.

With the rise in product liability litigation based on “failure to warn” over the past several decades, product safety labels have become a leading focal

point in lawsuits faced by capital equipment man-ufacturers.

In this article, I’ll share what I believe are some key best practices and “tools” that shape the current state-of-the-art for product safety label design. My goal is to give the machine design engineer, risk manager or in-house legal counsel some insight that will help formulate an improved safety label strategy that will better protect its products’ users from harm and its company from litigation-related losses.

Tool #1: The StandardsAs a manufacturer, you know that your legal obli-gation is to meet or exceed the most recent versions of standards related to your product at the time it is sold into the marketplace. Warning label standards are the first place you must turn when you define your product safety labels. Until 1991, there was no overarching, multi-industry standard in the U.S. (or in the world, for that matter) that gave definitive guidance on the proper formatting and content for on-product warnings. That changed nationally with the publication of the ANSI Z535.4 Standard for Product Safety Signs and Labels in 1991, and inter-nationally with the publication of ISO 3864-2 De-sign Principles for Product Safety Labels in 2004. Following the design principles in these standards will give you a starting place for both the content and format choices you have to make for your prod-

The importance of machinery safety labelsA matter of risk assessment, liability and compliance: Machine safety

labeling in the 21st century

By Geoffrey Peckham

Back to the Basics

34

ucts’ safety labels. Note that both of these standards are revised every five years or so, and it’s important to be aware of the nuances that would make one format more appropriate for your product than another.

Tool #2: Risk AssessmentFrom an engineering perspective, your job is to identify potential hazards and then determine if they need to be designed out, guarded or warned about. From a legal perspective, your job is to de-fine what hazards are “reasonably foreseeable” and “reasonable” ways to mitigate risks associated with hazards that cannot be designed out. Here is where risk assessment comes into play.

Risk Assessment Scoring MatrixIn today’s world, we should expect that a product is designed with safety in mind. The risk assess-ment process helps you to accomplish this task. At its most basic level, risk assessment involves consid-ering the probability and severity of outcomes that can result from potentially hazardous situations. After identifying the potential hazards related to your product at every point in its lifecycle, you then consider various strategies to eliminate or reduce the risk of people interacting with these hazards. The best-practice risk-assessment standards that ex-ist today (i.e., ANSI Z10, ANSI B11, ISO 31000, ISO 31010), give you a process to use to quantify and re-duce risks. Using these standards as the basis for a formalized risk assessment process not only will help you to develop better safety labels and a safer product, but it will also provide you with documen-tation that will help you to show the world that you are a safety-conscious company that uses the latest standards-based technology to reduce risks. This will be highly important should you be involved in product liability litigation down the road.

Tool #3: Global Warnings That Use SymbolsA large number of machinery manufacturers sell their products around the globe, and when this is the case, compliance with global standards is a re-quirement. The ANSI Z535.4 and ISO 3864-2 prod-uct safety label standards and the EU machinery di-rective, place an emphasis on using well-designed symbols on machinery safety labels so information can be conveyed across language barriers. Adding symbols also increases your labels’ noticeability. The use of symbols to convey safety is becoming commonplace worldwide and not taking advantage of this new visual language risks making your prod-uct’s safety labels obsolete and non-compliant with local, regional and international codes.

Note that sometimes symbols alone cannot con-vey complex safety messages. In these cases, text is often still used. When shipping to non-English speaking countries, the trend today is to translate the text into the language of the country in which the machine is sold. Digital print technology makes this solution much more cost-effective and efficient than in the past.

ConclusionThe safety labels that appear on your products are one of its most visible components. If they do not meet current standards; if they are not designed as the result of a risk assessment; and if they don’t in-corporate well-designed graphical symbols, your company risks litigation and non-conformance with market requirements. Most important, you could be putting those who interact with your machinery at risk of harm. Making sure your product safety signs and labels are up-to-date is an important task for ev-ery engineer responsible for a machine’s design.

I hope the above information has helped to set your company on the right path to revise its warnings.

35

Traditional machine safety is a lot like Ziebart or Rusty Jones. Remember those long-ago rust-proofing services? You’d buy a new or at least

late-model car, take it to one of their local shops, and they’d drill a bunch of holes in the body and spray in a rust-inhibiting coating. It seemed like a good idea at the time.

Well, I took a new 1987 Toyota Tercel to a lo-cal Ziebart, and it got the usual treatment, which I found out included sticking little plastic buttons into and over the new holes inside the door panel, rear hatch and other locations. Even then, this seemed a little goofy to me. I mean, punching holes in a new car didn’t seem like a logical way to pre-vent rust. Why not apply the anti-rust stuff during assembly and avoid all the holes? My concern only grew as the years went by, and I routinely saw rain-water dripping out of the drill holes and little, spi-dery trails of rust start branching out from under the plastic buttons. Terrific.

I’d bet the whole rust-proofing industry got started because the automakers weren’t doing it—given all the rusted hulks we used to see in moister parts of North America. So I’d also guess that Ziebart and other shops and their aftermarket dried up once the car builders started adding some of their own au-to-body preservatives before or during assembly. 

Similar to the rustproofing saga, machine safety used to be mostly a difficult and often ineffective afterthought. Gates, guards, E-stops, light curtains and other protective devices were added after ma-chines were built, but were so cumbersome that op-erators frequently bypassed them. In recent years, some standards, such as the National Fire Protec-

tion Assn’s NFPA-79 rules, have enabled safety and control communications on the same network. This enabled the advent of dual-processor safety PLCs and other components that can be designed into machines and production lines before they’re built, and help set up safe zones, safe speeds and safe directions in machines. These capabilities al-low operators to interact much more closely with machines with little or no risk of injury or having to completely power down. 

The main trick is to plan ahead, include safety functions in initial designs and get protections in-tegrated before equipment is assembled and tested. Many machine builders have adopted these prin-ciples and the devices and standards that support them. However, others have been slower to get on board because they’ve always built and guarded their machines a certain way, or they don’t know which standards apply to them, or they’re unaware how easy it is to apply new safety PLCs and other components. Changing mindsets is a lot harder than revising designs, and that’s why useful fore-sight is always in short supply.

One thing that could help reluctant builders get over the new safety learning curve a lot faster would be to make today’s standards much more available and accessible than they’ve been in the past. When-ever I cover machine safety, I’m always encouraged by everyone saying how important it is to get build-ers, system integrators and end users more educated about safety, but then I’m stunned at how few spe-cific details there are about what the primary ISO, IEC, ANSM, NFPA, UL, RIA and other standards require, where they must be applied, and how to

Help machine safety break free of the pastThe main trick is to plan ahead, include safety functions in initial designs and get protections

integrated before equipment is assembled and tested

By Jim Montague

Back to the Basics

36

comply with them. Most sources say builders must either shell out hundreds or thousand of dollars for their own copies of the safety standards or pay sys-tem integrators or certified consultants who are fa-miliar with the standards to advise them. 

I know standards organizations must be compen-sated for the resources they spend on developing safety standards. However, given the paltry details usually available, I also know they could do a lot more to provide basic guidelines and encourage-ment to builders seeking to add safety earlier in their machine design and prototyping processes. 

Of course, this improved outreach by many of the major safety organizations will be even more cru-cial as the standards themselves evolve and are up-

dated. For example, ISO 13849 just recently took over for EN 954, and builders need to know how to calculate safety performance levels, and not just how to fit into former safety categories. In fact, ef-forts are already underway to combine ISO 13849 with IEC 62061, and builders need more input on how this will affect them.

Heck, many suppliers and governments might be willing to fund greater dissemination of safety stan-dards to builders because it would mean greater use of safety PLCs and other products, and pre-vent some tragic injuries at the same time. Just like with rust-proofing, safety will eventually get where it needs to go, but why not give it some help along the way?

Automating functions. Simplifying operations.Modernizing protection.

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37

Before integrating safety into machine designs and production plans, it’s often necessary to confront some misconceptions and rationaliza-

tions against it. John McHale, engineering manager at ABB Jokab Safety, a products and integrated solu-tions supplier, and ABB Group member, in Westland, Mich., reports these common prejudices include:

•  There’s no place for safety in lean manufactur-ing. Safety will just impede operations, and all our processes will slow down.

•  Safety systems impede production.•  Cost of safety solutions is too high. It would cost

too much to upgrade every one of our machines.•  Safety systems stop people from doing their

jobs, and so they will just get bypassed anyway.•  Our process is too important to add safety sys-

tems. There’s no way I can shut this machine down because it makes the most money of any of our machines. If I shut it down, my bottom line and profits will be adversely affected.

McHale counters that, “One of our largest customers

had a fatality in its facility, and was fined $2.4 million by OSHA. Its experts also came in, ripped apart its pro-duction process, and gave them a government-mandated timeline to upgrade. It covered 180 machines, which cost $100,000 apiece, and had a two-year deadline. This didn’t include morale issues, doctor bills, cleanup bills, etc. This incident cost a huge amount of money.”

McCale adds that implementing safety doesn’t nec-essarily result in lost production, if it’s done properly with a well-formed team and effective communica-tion. For example, he says Jokab Safety recently up-graded a cardboard-box-making machine in Canada that prints, cuts and folds corrugated blanks, but its press had to be split apart to change dies and print heads or to add inks, and it had no safeguarding. “Inte-grating safety not only met applicable safety standards and regulations, but also reduced machine setup time significantly,” McHale says. “This machine averages six setups per shift, and at two shifts per day and 354 days per year, the 30 seconds saved per setup resulted in 35.4 hours of extra production per year.”

Machine safety pays its wayABB Jokab Safety reports five common prejudices machine builders must confront

By Jim Montague, Executive Editor

Technology in Action

38

About 15 years ago, one of my three daughters said we should set up a haunted house for Halloween. So we turned our old, one-car attached garage in

Skokie, Illinois, into a simple haunted maze. It was made mostly out of black and semi-translucent plas-tic sheeting stapled over nylon kite string attached wall-to-wall to form chest-high partitions.

After a few years, we built a two-car, detached ga-rage, and the Spooky Garage grew from five separate attractions or scenes to 10 or more. These include a falling battle axe; an eight-foot, newspaper-stuffed mummy that jumps up; a framed picture that drops out; a talking Frankenstein with glowing eyes and foam-insulation hands; and a circular saw that turns on by itself. Both the axe and the mummy are ac-tuated manually via black clothesline strung along the ceiling, and my family, friends and simple wire-less switches do the rest. Over the years, the Spooky Garage has become a neighborhood institution,

Real machine safety applications in the spooky garageIt’s been helpful to be reminded that machine safety’s best principles

can be usefully employed in situations beyond the plant floor

By Jim Montague

MONSTROUS RISK ASSESSMENTAn internally lit, voice-activated Frankenstein figure with

green-painted, foam- insulation hands is safetly secured to a

wall in the Spooky Garage.

JIM

MO

NTA

GU

E

Technology in Action

39

averaging about 200 trick-or-treaters and their fam-ilies annually. 

Because scaring people can be a bit risky—some moms jump back through the partitions—I also try to make the Spooky Garage as safe as possible. So even before covering machine safety, I noticed that I was unconsciously and organically perform-ing what I’ve since come to recognize as basic risk assessments and human-factors engineering to pro-tect my visitors, assistants and myself. I examine each situation we’ll be in, evaluate the severity and frequency of each potential threat, design it out or mitigate it in some way, or repeatedly train and warn each participant about how to avoid it.   

On the mitigation front, I realized early on that being startled puts people slightly off balance, so I never put them in situations where they have to step up or down or otherwise risk tripping. Second, I initially thought about making the battle axe out of plywood, but dropping it near someone’s head could be dangerous, so I substituted light foam board covered with aluminum foil. Third, the mummy’s booted feet are tied to his chair, so he can’t swing out when he jumps up. Fourth, Fran-kenstein’s arms are on hinges and can move towards visitors, but they’re heavy and hard to control, so

I’ve immobilized them, and had to be content with his eyes just lighting up and his voicebox growling “You cannot escape!” Fifth, the circular saw is tied securely to the wall and has the usual safety guard, but I also decided to take out the blade to remove any possible threat from it.

On the warning and training side, I require vis-itors to take off masks and hats, so they can ori-ent themselves better. And I tell parents and taller kids to watch out and bend down to avoid the ny-lon strings. I’ve even tied plastic strips to the strings so they’re easier to avoid. Volunteers behind the picture and in costume on a couch near the end also are trained not to get too close to the visitors to avoid the occasional panicked slap or fist. 

So far, despite all the screams and people run-ning out of the Spooky Garage, we haven’t had any injuries—although some candy, little tiaras and foam ninja stars have been left behind. Anything could happen, of course, but I think continually considering each interaction in this mostly man-ual mechanism has allowed me to remove almost all potential difficulties and preserve the healthy thrills and chills. It’s been helpful to be reminded that machine safety’s best principles can be usefully employed in situations beyond the plant f loor.

40

Machine safety must be more than an afterthought.In the old days, machines were built, and guards and other safety features were added later, which wasn’t very efficient. More recently, many builders make safety an integral part of their design process, and new safe-speed and zone-control technologies and harmonizing international standards are help-ing them. And, not only does this proactive, preven-tive approach reduce the frequency and severity of potential accidents and injuries, it pays added divi-dends of increasing machine efficiency and reduc-ing downtime.

“Validation of safety systems is a process that needs to be planned,” says Steve Zuberbier, en-gineering technical leader for family care R&E at Kimberly-Clark, which makes Huggies, Kleenex, Scott, Kotex and other products. “If you don’t plan, you will fail. Will validation cost your company more effort? Yep. Will it cost you more time, re-sources and money? Yep. But, we’ve seen our safety validation effort pay for itself over and over again.”

Zuberbier adds that safety problems occur be-cause of people. “My safety controller will perform consistently,” he says. “My humans will not. Using an engineered, controlled system provides a more reliable safety solution and keeps our people safe. The effort it takes to validate a safety PLCis much greater than it was with the old hardware relays be-cause we didn’t have to worry about programming the I/O points. However, we haven’t bought a single machine since 2007 that doesn’t have a safety PLC system. And, we’ve taken validation from 48 to 72 hours down to six to 12 hours now.”

Savings Go With SafetySimilarly, Automatic Handling International (AHI) in Erie, Mich., makes roll-handling and packaging machines for tissue, non-woven materials, convert-ing and other applications, and it recently began designing andintegrating more safety capabili-ties  into its equipment to eliminate hazards, but also to drive costs out of its engineering and man-ufacturing processes by getting them to work to-gether in a more integrated fashion.

“We were still doing hardwired safety in 2007, but these are big systems, and so the question was how to protect everything because you might not know where everything is,” says Dan Pienta, AHI’s president. “What are the zones going to be? Who’s going to enter those zones? What do we want to keep safe? We learned how to do a good process to work with a hardwired safety system, but it was a challenge because every system was different — ev-erything was custom.” 

Pienta reports AHI moved to DeviceNet when  Rockwell Automation  launched its Guard-Logix controls, which combined PLC and safety communications in one device and used the same network, but maintained two separate micropro-cessors. Later, AHI adopted EtherNet/IP when that protocol offered integrated safety, and standardized on GuardLogix and Safety Point I/O.

“It can be a tough transition to implement a new technology,” Pienta explains. “I might not be sure how to implement in a way that I might need for the future, so you have to kind of feel your way through it. It’s not that safety is so complex, but

Buckle up with built in safetyMachine builders include preventive safety early in the design —

and get paid back sooner

By Jim Montague

Technology in Action

41

we do 100 projects per year. Safety is a small part of our business, but it impacts every part of it. So, when safety on Ethernet came out, it made a lot of sense because it allows us to use standard hardware and stay f lexible, but also give our customers the most reliable systems. Safety has to be part of what you sell because it can help customers be more pro-ductive, reduce risk and add value.”

Update the Attitudes and CulturesNo doubt, the biggest roadblock to integrating safety into machines, production lines and plants is changing the minds of managers and operators from the old belief that safety is a drag on opera-tions and the bottom line to a new belief that safety is a doubly worthwhile investment than can be profitable and prevent injuries and accidents.

For example, research by the  Aberdeen Group  shows there are clear correlations between success in reducing injury rates with reducing un-scheduled downtime and much higher overall equipment effectiveness  (OEE) levels. Its studies found that best-in-class performers had 5-7% higher OEE, 2-4% less downtime, and less than half the injury rate, according to Steve Ludwig, Rockwell Automation’s program manager for safety.

However, altering the old, safety-is-a-burden mindset can be devilishly hard. “I grew up in au-tomotive plants, so I’m aware that safety and pro-ductivity have been at odds,” says George Schuster, senior industry specialist on the automotive team at Rockwell Automation. “They knew the more safety processes they put on their systems, the more they’d hinder their productivity or profits. They knew it. It was almost in their DNA.”

More recently, the productivity and safety ropes seem to be pulling in the same direction. A De-cember 2012  Control Design survey on machine safety  found that, besides wanting to prevent per-sonal injury or meet regulatory requirements, ma-chine builders most often would change their safety

implementation because of potential lost produc-tion on the machine. In fact, about 90% of those surveyed list the prevention of personal injury as the key reason for changing safety on their ma-chines, which was higher than the 75% that make a change to meet regulatory requirements.

“The people who establish corporate cultures are less and less conflicted about productivity and safety than they’ve been in the past,” Schuster adds. “Safety is a tool that machine builders use to improve pro-ductivity and yield. It’s a huge differentiator.”

Simplicity Gets to Safety SoonerTwo of the main forces enabling safety to be added to machine designs earlier are controllers that combine safety and control functions, and fieldbuses and Ether-net networks that require less cabling and connectors.

Pienta adds that AHI cut the time it takes to build and finish its roll-handling and packaging systems by using Ethernet, and combined control and safety components. “We’re not wiring as many distrib-uted I/O and other connections back to the main panel,” Pienta says. “It’s all going to the Guard-Logix. When you have fewer connections, it takes less time when you power that panel up and start doing your I/O checks. That has a lot of value. We also get value from safety validation, making sure our safety system works and documenting it. We want to show the insurance guys that we’ve done our due diligence, and that our systems are as safe as we can make them. This lowers our risk and re-duces our liability.” 

SAFER RING SPINNING Figure 1: Eagle Technologies’ spin/friction welder for plastics

implemented servomotors and drives with embedded software

that stops motion to allow operators to access the weld area, but

doesn’t power down, which reduces motor strain and wear.

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Similarly,  Eagle Technologies  in Bridgman, Mich., needed to reduce waste and improve the safety capabilities of its spin/friction-welding ma-chine for plastics, especially the f luid-filled, 2-ft-di-ameter, plastic rings that balance loads in washing machines (Figure 1). The rings are made from two parts — one held in place, while the second is spun and pressed down onto the first, creating a leak-proof weld in less than 30 seconds.

However, one appliance parts maker was experi-encing 15% material waste and scrapped parts from leaky welds, while its welders’ low-speed, high-torque process strained their motors so much that they needed annual rewiring. The welders had to be powered down and handle 480-Vac drops every 4-5 minutes, so their operators could reach in to re-move parts and make needed adjustments.     

Eagle’s spin/friction welder redesign began withIndraMotion  servo platform, which uses Eth-ernet-based sercos III to integrate the machine’s motion logic control directly in the drive without a separate PLC. This motion and logic control-ler from  Bosch Rexroth  works with its digital, in-telligent servo drives and synchronous servo mo-tors to drive the spin/friction welder’s three-stage, planetary gearbox, which allows less-stressful, low-speed, high-torque motion of the welding head on its ballscrew and rails.

In addition, Eagle employed  Bosch Rexroth’s Safety on Board, which embeds programmable, safety-based logic directly in the servo drives to eliminate the need for the lock-out/tag-out stop-pages that were straining the motors, but without requiring external safety hardware. Operator pro-tection is further built into the welder by servo drives that respond to signals from its light cur-tain via dual, redundant safety channels that put the machine into one of two pause modes — Con-trolled Stop 1 or Controlled Stop 2 — which stop its motion, but still feed power to it, and allow easy restarts without complete resets.

“Usually a weld machine design starts with a PLC, and then the designer builds out from there,” says Earle Cooper, Eagle’s project manager. “In-draMotion let us start with control of two axes al-ready built into the servo drive, so we could focus on options for creating different types of welds and parts.” He adds that scrap material from the end user’s balance ring application dropped from 15% to less than 1%, and productivity was maintained at less than 20 seconds per ring, while the safety system conforms to EN954-1, Category 3, and sup-ports new  ISO 13849 standards. “We still don’t know exactly how much longer the motors are last-ing than before because none have required any re-pairs,” Cooper remarks.

In Software, On the Network Beyond aiding individual machines and produc-tion lines, safety principles and tools created and deployed in software also can be integrated onto different machines, and even scaled up to entire fa-cilities and multi-plant organizations.

For example,  Baader-Johnson  in Kansas City, Kan., builds machines for processing and convey-ing poultry, fish and other meats, and uses PC-based controls and integrated safety tools from  Beckhoff Automation. Baader-Johnson deploys an embedded PC, and then connects distributed EtherCAT safety I/O terminals, with integrated TwinSafe safety PLC, to manage safety tasks at its clients’ plants, while also adjusting safety zones by using TwinCAT as its stan-dard TwinSafe programming tool.

“TwinSafe helps us implement safety functions for e-stops and in other areas,” says Ryan Foltz, sales project manager at Baader-Johnson. “On plantwide projects, it’s beneficial to use EtherCAT terminals as the standard I/O system, but TwinSafe makes it pos-sible to shut down our machines and conveyors very quickly if anyone on the plant floor enters an un-safe part of the machine. Our former e-stop meth-odology was rather cumbersome, especially in large

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applications. TwinSafe cuts down on wir-ing, and provides the flexibility to prop-erly manage our safety implementations.”

Also,  Teepack Spezialmaschinen, Meerbusch, Germany, says its new Per-fecta tubular teabag filling, bagging and packaging machine (Figure 2) runs a variety of products at about 400 bags per min-ute with thread and label or with paper or foil pack-ets. It achieves this 20% boost in its performance by combining IndraMotion for Packaging software with decentralized servomotor and controls, sercos III networking, Safety on Board software and an In-draMotion controller from Bosch Rexroth.

In fact, Perfecta even runs automatic, online safety tests in the background to create performance prerequisites for its continuous 24/7 operating sched-ule. To perform this job, Safety on Board uses sev-eral certified safety tools, such as safe stop/operation stop and safe movements in the form of reduced speed, maximum torque or turning direction. These tasks run directly in the drive, which shortens their reaction times to less than 2 msec, according to Tee-pack, while other safety solutions have to interrupt a machine cycle for coercive dynamization of up to eight hours to detect “dormant bugs.”  

“We can activate the additional modules and necessary servo drives on the respective machine via the user interface. This reduces the variety of the software and allows quick, subsequent integra-tion of additional modules,” adds Andreas Meyer-ing, Teepack’s head of electrical engineering and software development.

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TIME FOR TEA BAGSFigure 2: Teepack’s Perfecta machine can fill and produce

400 bags per minute with thread and label or with outside

paper protection, using decentralized servomotor control, and

automatic safety tests that run in the background to create

prerequisites for 24/7 operations.