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International Journal of Mechanical Engineering and Technology (IJMET)

Volume 9, Issue 10, October 2018, pp. 121–134, Article ID: IJMET_09_10_011

Available online at http://www.iaeme.com/ijmet/issues.asp?JType=IJMET&VType=9&IType=10

ISSN Print: 0976-6340 and ISSN Online: 0976-6359

© IAEME Publication Scopus Indexed

EMERGENCE OF SMART MANUFACTURING

SYSTEMS: MITIGATION OF SYSTEM LOSSES

AND ENHANCING FLEXIBILITY IN INDIAN

COMMERCIAL VEHICLE INDUSTRY

Palavesa Murugan R

Assistant General Manager, Manufacturing, Ashok Leyland, Chennai, Tamil Nadu, India

Dr. Pon. Ramalingam

Registrar, Hindustan institute of technology & science, Chennai, India

ABSTRACT

Market turbulence, aggressive competition and rapid changes in manufacturing

methodologies and technologies are putting manufacturing operations under

increasing pressure. The various types of manufacturing system losses and the

importance of the system flexibility to overcome the losses in the current scenario are

important. The customer’s changing needs, the shorter life cycle of products; the

growing trends of product variability and the customer’s expectation on shorter lead

time are insisting the compelling need of a shift from dedicated mass production

assembly lines to mixed model assembly lines in Indian commercial vehicles industry.

Keywords: Manufacturing System, Manufacturing system losses, dedicated assembly

line, Multi model assembly line.

Cite this Article: Palavesa Murugan R and Dr. Pon. Ramalingam, Emergence of

smart manufacturing systems: Mitigation of system losses and enhancing flexibility in

Indian Commercial Vehicle industry, International Journal of Mechanical Engineering

and Technology, 9(10), 2018, pp. 121–134.

http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=9&IType=10

1. INTRODUCTION TO MANUFACTURING SYSTEMS

A manufacturing system is a complex arrangement of physical elements characterized by

measurable parameters. Manufacturing system refers to a series of arrangement of operations

and processes used to make a desired final product or component. A collection of integrated

facilities and human resources, whose function is to perform one or more processing and or

assembly operations on a starting raw material, part, or set of parts. It includes the actual

equipment‟s for composing the processes and the arrangement of those processes. Ref: Figure

1.

Emergence of smart manufacturing systems: Mitigation of system losses and enhancing flexibility

in Indian Commercial Vehicle industry


Figure 1 Source: Internet

The manufacturing process consists of manufacturing processes and assembly operations,

material handling technologies, automation and control technologies and quality control

systems at factory level and enterprise level manufacturing support systems and quality

control systems to deliver the value adds. Refer Figure 2.

Figure 2 Manufacturing processes

The production system consists of facilities and manufacturing support systems to

accomplish the entire process. In a manufacturing system, if there is a change or disturbance

in the system, the system should accommodate or adjust itself and continue to function

efficiently. Normally the effect of disturbance must be counteracted by controllable inputs or

the system itself.

2. REVIEW OF LITERATURE

According to Stefan Thomke and Donald Reinertsen as stated in Agile Product Development:

Managing Development Flexibility in Uncertain Environments, CALIFORNIA

MANAGEMENT REVIEW VOL. 41, NO. 1 FALL 1998, The term “flexibility” is used in

Palavesa Murugan R and Dr. Pon. Ramalingam


many contexts, here we propose the following operational definition: Development flexibility

can be expressed as a function of the incremental economic cost of modifying a product as a

response to changes that are external (e.g., a change in customer needs) or internal (e.g.,

discovering a better technical solution) to the development process. The higher the economic

cost of modifying a product, the lower the development flexibility.

Assembly line balancing is considered as a technique by which the tasks are distributed in

different workstation, so that the goal which was predetermined is achieved (Kumar & Mahto,

2013). Line balancing is a method of levelling the workload across different work station,

processes or value stream, to remove the bottle necks and excess capacity which is not

required. If the line is not balanced constraints slows the process and it will lead to waiting in

the downstream operations and more capacity will lead to a consequence of waiting and

adsorption of fixed cost. Assembly line balancing is often referred to as a decision-making

process to assign tasks to workstation in a serial kind of production process. (Kumar &

Mahto, 2013).

Various researchers have attempted to address the complexities in manufacturing system

and resolution from various industries, however there are very less broad level method

towards mitigation of manufacturing system losses and countermeasures for resolution of

work imbalance in mixed model assembly lines for commercial vehicle industry.

3. THE EMERGENCE OF MANUFACTURING ASSEMBLY LINES - A

BRIEF HISTORY

The greatest innovations of the 20th

century was the assembly line. It shaped the industrial

world strongly that businesses that couldn‟t adopt the practice soon became extinct, and it was

one of the key factors that helped in reduction of the manufacturing throughput time at least

by 500 percentage.

3.1. The Early Assembly Line Concept

The earlier age to the industrial revolution, each expert would create his own parts with own

hands and simple tools, which was the portion of the final product and the manufactured

goods were usually made by hand with individual workers. The final product was made by

bringing those all portions together.

As early as the 12th century, 16,000 workers in the Venetian Arsenal produced ships by

moving them down a canal where they were fitted with new parts at each stop. During its

most successful peak time, rate per day was one ship.




3.2. Innovation that changed the manufacturing world

The earlier days of 20th

century, One hundred years ago today, Henry Ford and his team at

Highland Park assembly plant launched the world‟s greatest contribution to manufacturing –

the first moving assembly line. It simplified assembly of the Ford Model T‟s 3,000 parts by

breaking it into 84 distinct steps performed by groups of workers as a rope pulled the vehicle

chassis down the line. Refer: Figure 3

Figure 3 The world‟s first moving assembly line

The new process revolutionized production and dropped the assembly time for a single

vehicle from 12 hours to about 90 minutes.

By reducing the money, time and manpower needed to build cars as he refined the

assembly line over the years, Ford was able to drop the price of the Model T from $850 to less

than $300. For the first time in history, quality vehicles were affordable to the masses.

Eventually, Ford built a Model T every 24 seconds and sold more than 15 million worldwide

by 1927. Thus, the first moving assembly line laid down the foundation by focusing on Cost,

Quality and Delivery.

4. SYSTEM LOSSES

INPUTS Performance Indicators

Demand

Information

Material

Quality

Cost

Delivery

System Losses

Waste

Variability Inflexibility

People & Process Flexibility

https://media.ford.com/content/fordmedia/fna/us/en/features/celebrating-the-moving-assembly-line-in-pictures.html



Figure 4 System losses due to Waste, Variability and inflexibility.

The way physical assets and resources are configured and optimized to create value and

minimize losses is known as an operating system. To reduce or eliminate the gap between the

expectation and actual performance, the industries need to focus on minimizing the system

losses, i.e., Waste, variability and inflexibility. Refer: Figure 4.

The system losses are the critical causes to create a gap between customer and shareholder

aspirations and actual performance. Refer: Figure 5.

Figure 5 Impact of system losses on business performance

The need of the hour is manufacturing industries need to continuously focus, sustain and

improve the deliverables on Quality, Cost and delivery metrics for which the flexibility is

vital. Refer: Figure 6.

To improve performance, the losses should be understood and relentlessly eliminated.

Within any system, the losses of waste, variability and inflexibility will inhibit performance.

These wastes increase cost while adding no value from the customers perspective. They also

extend the period of return on investment (ROI). Identifying “Value” in the eyes of the

customer is a critical starting point in an operational transformation.

Figure 6 Methodology to minimize the system losses.

Performance

Customer/Shareholder aspirations

Gap = Business Problem

Time

Actual Performance

Waste Variability Inflexibility

Sample distribution

LCL UCL

6 “sigma” (s.d.)

LSL USL

Typical focus of

lean improvement

work

Typical focus of

“six sigma” improvement

work

Typical focus of

Mass Customisation

activity

“voice of the process”

“voice of the

customer”

Additional

CostHigher

spec.

Price

customer will pay

Cost to

Customer

Basic

spec.




4.1. Waste

Certain production system, like Canadian Production System, Toyota Production System and

Caterpillar Production system have laid emphasis on wastes like,

1. Over Production

2. Waiting

3. Transportation

4. Over Processing

5. Inventory

6. Rework

7. Motion

Each of the 7 elements of waste control are key to wealth conservation in directly

impacting business.

4.1.1. Over Production

Over Production waste occurs when we manufacture or assemble more than what is needed.

Overproduction can be identified by processes producing more than is being “PULLED” by

the customer.

The primary causes can be misuse of automation, long process set-up, unleveled

scheduling, unbalanced work load and over engineered manufacturing lines. The same can be

reduced by improving change-over and set-up times and balancing production lines.

4.1.2. Waiting

Waiting waste come from people, process or partially finished goods sitting idle while waiting

for information, material or machine. Waiting can be identified by idle people or machines

waiting on the preceding or following operation, materials, schedules or information.

The primary causes can be unbalanced work load, unplanned maintenance, Long process

set-up time, Misuse of automation, upstream quality problems and unleveled scheduling. The

same can be reduced by Refining cycle time, Schedule work load and Improve balancing of

production line.

4.1.3. Transportation

Transportation waste occurs when people, product, equipment or information are moved more

often or further than required. This can be identified by internal movement of People,

materials or information that does not add value to a process. Layout modification is the best

way to mitigate the transportation wastes.

4.1.4. Over Processing

These wastes are caused by making a product or service excess than a customer needs or is

willing to pay for. Vestigial features that are not required with respect to customer perspective

is classical example. The same can be identified through Customer survey, Field reports and

Checking of defective / returned components. By enhancing product knowledge at customer

end usage over processing can be eliminated.

4.1.5. Inventory

Inventory wastes hide many problems. Excessive inventory coverups quality problems,

manpower and or production scheduling problems, excessive lead time and vendor problems.

Inventory can be identified excessive inventory of raw materials or finished goods. The same



can be caused by Product complexity, unleveled scheduling, poor market forecast, unbalanced

work load, unreliable shipment by suppliers, miscommunication and reward systems. The

same can be controlled by JIT and KANBAN material in-warding management systems,

accurate product forecast, proper scheduling and improving the balancing of production lines.

4.1.6. Rework

Rework waste happens when we don‟t have robust preventive systems like Poka-Yoke /

Mistake proofing techniques. It can be identified by defective, partial or un- completed

products or services and completed units that are reworked or thrown away. The probable

causes can be weak process control, poor input product quality, unbalanced inventory level,

poor maintenance of machinery, inadequate education/training/work instructions, product

design and or customer needs not fully understood. Rework can be reduced by improving

visual control, SOPs and mistake proofing.

4.1.7. Motion

It is the unwanted movement of people, product and or equipment‟s that doesn‟t add value to

process or product. This can be identified by excessive walking, moving or handling and

prepare a complex diagram of the actual process flow. The primary causes are poor

people/machine effectiveness, inconsistent work methods, unfavorable facility or cell layout,

poor workplace organization and housekeeping. The motion wastes can be reduced by value

stream mapping of every process and reduce unwanted movement.

4.2. Variability

Variability either causes quality or delivery problems to the customer or increases cost due to

adding contingency to make customer happy. Often in practice, variability is initially dealt

with by adding contingency. However, this adds cost and often does very little to protect

outputs (particularly in build to order type environments). Attacking the variability means that

the contingency is not necessary and will also reduce costs in other ways.

The source of variability can be Man, Machine (Process)/ method, material, information

and or environment.

4.2.1. People

Defects generated are depended on operator skill level. i.e., Operator A creates more rework

than Operator B. Standard operating procedures will greatly help to reduce variability caused

by skill level gaps.

4.2.2. Process

Process variability is caused by Operator Method and Machine issues. By focusing on Overall

equipment effectiveness, the variations by machine get addressed. The efficient work load

balancing reducing the variability on delivery. Use root cause analysis, 6-sigma tools,

standardised work, kaizen and levelling to understand and attack the causes of process

variability.

4.2.3. Material

Material variability is caused by input quality and delivery time of material arriving at a

process. “Suppliers” in this sense includes internal processes that act as suppliers to

downstream processes, not just external suppliers. The input quality impacts the defect rate

and affects the quality and delivery of the final product. Similarly, the delayed receipt of

material affects the delivery promises of any firm.




4.2.4. Information

Information variability is caused by the quality and release timing of information. Inaccurate

forecasts may lead to shortfall of raw materials for Product B and surplus for Product A and

vice versa. We need to standardize and simplify the information collection and formatting.

Have a reactive (flexible) process that does not heavily rely on accurate forecasts.

4.2.5. Environment

Environment variability covers things such as changes in temperature, humidity etc., which

can affect the process. A good example of environmental factors being important is in

microprocessor production, where manufacturers use rooms with constant temperature and

humidity all the time. This is because experience has shown that changes in environmental

conditions can cause large changes in yields. Need to Protect the process from changes in the

environment or make the process resilient to them.

Variability and Waste are inextricably linked; reducing waste requires variability to be

reduced. During an operational transformation, standardising work is one of the first steps that

needs to be taken. This will reduce variability in the main but will also improve the average

performance of each process as the current „best practice‟ way of operating will become the

standard. After this, kaizen activities will improve the standard further.

4.3. Inflexibility

Inflexibility causes either additional costs if absorbed, or customer disappointment if passed

on. Inflexibility adds to the “Cost of Variety”, increasing cost and / or restricting the range of

products that can be offered.

Figure 7 Importance of flexibility in high variety product scenario

Source: Agile Product Development for Mass Customization, David M. Anderson (1998)

Inflexible Systems, geared to low per unit costs, may be cheaper only where

market variety is very low

High

Low

Low High

Va

rie

ty

Co

sts

Product Choice

Flexible

System

Inflexible

System

e.g. Model

T Ford

e.g. Dell

Computers



Flexible Systems always offer lower total costs in any other case

Today, markets with very low market variety are very rare

4.3.1. Ford Model T Manufacturing

The Model T brought mobility and prosperity on an undreamed-of scale through

manufacturing efficiencies at a price that anyone could afford. The mass production process

perfected the moving assembly line, creating and defining the industrial age and enabling

Ford to steadily decrease the price of the Model T. In 1908, the first Model Ts sold for $825.

By 1925, it sold for only $260.

The conventional assembly line practice as developed by Henry Ford and Charles

Sorensen. A single product moves along a conveyor and at each station, workers assemble

various items. The entire line changes to a different product on a fixed schedule and then

assembles this product for a scheduled period before changing to the next product. Refer:

Figure 8.

Figure 8 Batch Production with changeover

4.3.2. Dell Model Manufacturing

Boxes of Intel microchips and electronic components from supplier by on double-decker

conveyor belts. Workers read orders off a monitor and assemble a new Dell desktop computer

every three to five minutes. 100% Make to Order scenario. The finished boxes, more than

25,000 on a typical day, then trundle off on other conveyors to be shipped directly to

customers. The whole system is designed so tightly that the factory rarely needs more than

two hours' worth of parts inventory. Parts storage takes up roughly the space of an ordinary

bedroom. Nobody makes computer hardware more efficiently than Dell.

4.3.3. Multi Model Manufacturing

Mixed Model Production is the practice of assembling several distinct models of a product on

the same assembly line without changeovers and then sequencing those models in a way that

smooths the demand for upstream components. The objective is to smooth demand on

upstream work centers, manufacturing cells or suppliers and thereby reduce inventory,

eliminate changeovers, improve Kanban operation. It also eliminates difficult assembly line

changeovers. Refer: Figure 9.




Figure 9 Mixed model assembly line without changeover

4.3.4. Types of inflexibility

The Manufacturing Advantage, Slack (1990) talks about four types of inflexibility.

1. Volume

2. Mix

3. Delivery

4. Product

4.3.4.1. Volume

Inflexibility of Volume manifests itself by an inability to cope with changes in total customer

demand. Often, when demand is less than capacity, stock is built up (causing inventory and

overproduction). When demand is greater than capacity, use up stock (or let down customer if

you don‟t have enough stock). Usage of Flexible Manpower Systems and Pull Systems to

allow capacity to be flexed.

4.3.4.2. Mix

Inflexibility of Mix manifests itself by an inability to change between products to meet

changing customer demand. Traditionally change over reduction is used to free up capacity

that was previously used for change overs. Whilst there is nothing wrong with this per se, in

an operational transformation we aim to reduce changeover time to allow more change overs

to occur within the same total amount of change over time. In this way batch sizes can be

reduced, allowing inventory and other forms of waste to be reduced and flexibility increased. Usage of SMED, flexible machinery / manpower, and standardised work to allow fast changes

in product mix.

4.3.4.3. Delivery

Inflexibility of Delivery manifests itself by an inability to deliver to the exact lead times the

customer wants. Need to reduce manufacturing lead times so that whatever the customer

wants can be built and shipped quickly.

4.3.4.4. Product

Inflexibility of Product manifests itself by an inability to provide the product or service the

customer wants.



5. ASSEMBLY LINES

An assembly line is a sequence of workers and machines that each perform a set of specific

tasks on a product that move it closer to a finished form. The primary benefit of assembly

lines is that they allow workers and machines to specialize at performing specific tasks, which

can increase productivity. Large-scale assembly lines can allow for mass production of goods

that would not be possible if products were made from start to finish by a single worker. The

high productivity of mass production can also result in lower cost per unit produced than

other manufacturing methods.

5.1. Dedicated Assembly lines for uniform product

In the early days of automation, the dedicated mass production assembly lines designed to

attain high productivity for a single model in very large quantities. The benefit of using an

assembly line in the manufacturing process is that a regimented production process helps

ensure a uniform product. In other words, the products made by an assembly line are not

likely to exhibit much variation.

5.2. Inflexibility

Assembly lines are geared toward producing a specific type of product in mass quantities,

which can make a company less flexible if it wants to shift production to different types of

products. For example, the machinery used on an assembly line used to make one specific

automobile might have little application for other tasks. Shifting operations to produce

different products in an assembly line environment can be costly and might require additional

training and the purchase of new machinery. To cater the customers changing need to meet

their varied business needs, the manufacturers need to shift for a mixed model production line

rather than dedicated assembly lines.

5.3. Multi model assembly line

An Example

The Medium and Heavy-duty commercial vehicles are classified based on the application as,

1. Haulage Vehicles

2. Tipper Vehicles

3. Tractor Vehicles

Depending the application, the discrete fitments like Tipping gear arrangement, Fifth

Wheel coupling arrangement make the assembly sequence and fitments going for a change.

Henry Ford Philosophy: You can have any colour you want as long as it’s black

Need of the Hour: Customer configured vehicles




Based on configuration of driveline the vehicles are classified as 4X2 (Two axle Vehicle),

6X2 (Three axle vehicle), 8X2 (Four axle vehicle) & 10X2 (five axle vehicle). 8X2 and 10X2

Models need to be produced with option one of Twin steerable axles and option two of Lift

Axle. Refer: Figure 10.

Figure 10 Different models of Indian Commercial vehicle by driveline configuration

These are the uniqueness in product design and discreteness of fitments can be easily

managed in dedicated assembly lines. The various models of a product have a wide range of

similarities and difference.

5.4. Work Balance

The work imbalance is creating the underutilization of manpower and equipment‟s and it is an

endanger to installed capacity of the money invested.

5.4.1. Inherent Balance

Inherent balance attempts to provide each workstation with precisely the same amount of

work. With high-volume assembly lines, this may be achievable, to some degree. Manual

assembly is flexible because people are flexible. Analysts divide the work into minute tasks.

They reassign these tasks to work stations such that each station has the same cycle time.

Balancing mechanized or automated production lines with this method is more difficult since

it is rarely possible to find equipment with identical cycle times.

The most formidable problem of inherent balance comes from variation from one cycle to

the next. The work times developed by traditional time study show average deterministic

4X2 Model

8X2 LA Model

10X2 TS & LA Model

8X2 TS Model

6X2 Model



times of great accuracy. In reality, these times may vary significantly from one cycle to the

next. The time at a given station is, in fact, a distribution. When the time on a station is longer

than the average, it slows the entire line. When the time on a given station on a particular

cycle is less than average, it cannot speed up the line. Thus, the real performance is less than

the average cycle times indicate. The more stations, the more this variation affects

performance.

Due to the fitment variations of the number of axles to be mounted itself drastically

varying, the line to be balanced for optimum number of axle models. So that the idleness of

manpower and or equipment will be smoothened for the model mix or else the line needs re-

balancing during every model change which is nothing but a forced batch production.

5.4.2. Surplus People Balance

Surplus balance means that we simply ignore the imbalance and allow some people to have

less work. While surplus capacity is a reasonable method for balancing machines, particularly

inexpensive machines, it rarely is acceptable for balancing people. When customer delivery is

critical and customer demand irregular, surplus capacity may be used to ensure fast delivery.

5.4.3. Queuing Balance

When operators have permanent stations in a cell or line, queuing between them compensates

for cycle-to-cycle variation. Floating-fixture assembly lines work on this principle. If the

average work times differ, queuing alone is insufficient. Queuing alone balances the short-

term or dynamic variations, but it will not compensate for longer-term static variation.

5.4.4. Floating Balance

Floating balance, usually combined with queuing, is frequently a good method for balancing

people. Here, operators monitor the queues to determine which stations are working ahead

and which are falling behind. Operators move to the stations that are falling behind and assist

until that station is caught up. This requires that stations allow for multiple operators when

necessary.

5.5. Advantages with mixed-model assembly lines

Increased volume flexibility.

Increased mix flexibility.

Reduced product dedicated costs.

More consistent quality.

Shorter takt time.

One assembly flow is a driver for commonality and common product architecture.

5.6. Disadvantages with mixed-model assembly lines

Difficulties in handling the increased time losses in the assembly system.

Increased sensitivity to disturbances

6. CONCLUSION

Mixed Model Assembly can be an important technique for achieving the smooth, simple

workflows of Lean Manufacturing. Mixed Model Production is the practice of assembling

several distinct models of a product on the same assembly line without changeovers and then

sequencing those models in a way that smooths the demand for upstream components.




Traditional mass production was based on dedicated assembly lines where only one or few

products were assembled in large quantities and thereby achieved a high productivity by the

principles of economies of scale. In today‟s marketplace where customers demand high

product variety and short lead times, mass customization has been recognized as the new

paradigm for manufacturing. Mixed model assembly lines are considered to be an enabler for

mass customization and are therefore today replacing many of the traditional mass production

assembly lines in industrial environments. Mixed model assembly lines are advantages in

Quality, Cost, Delivery aspects with high flexibility in volatile volume and high model mix

scenario by reducing the system losses.

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(1990)

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