zahran - training final report

Marwan Shehata Mohamed | Summer Training | August 20, 2016

Student Training Report PRESENTED TO TRAINING COMMITTEE

About the organization

Zahran Group for Household (S.A.E.) is the leading manufacturer and distributor of Small Household Equipment in Egypt.

The company was founded in 1967 by Engineer Mohamed Zahran (1919 – 2006). With headquarters in Alexandria, Egypt,

the company has 2 manufacturing facilities and 11 stores across Egypt. Since 1973, Zahran has been the sole authorized

distributor and licensed manufacturer of France's Tefal, the leading non-stick cookware maker worldwide.

Zahran has 6 main product lines: Non-Stick Cookware (Tefal), Stainless Steel Cookware, Aluminum Cookware, Pressure

Cookers (Tefal), Electrical Appliances and Plastic Kitchenware.

The company operates as both a manufacturer of its own brands as well as a key importer and distributor of international

brands, including Tefal, Moulinex, Brabantia, Leifheit and Soehnle.

FACTS

Established: 1967

Paid-In Capital: EGP 250 million (approx. USD 45 million)

Export Markets: Middle East, North Africa, Europe

Certificates & Awards: ISO 9001:2000 ISO 14001:2004 OHSAS: 18000:2007.

Main Products

Stainless Steel

Aluminum

PlasticsNon-stick

Electrical Appliances

Stainless Steel Products

Stainless steel pots use 18/10 grade, this grade and 18/8 are the two most common grades of stainless steel used for food

preparation and dining, also known as Type 304 (304 Grade) and are part of the 300 series. The first number,18, refers to the

amount of chromium present and the second represents the amount of nickel. For example, 18/10 stainless steel is

comprised of 18% chromium and 10% nickel.

18/10 grade stainless steel is also comprised of no more

than 0.8% carbon and at least 50% iron. The chromium

binds oxygen to the surface of the product to protect the

iron from oxidation (rust). Nickel also enhances the

corrosion resistance of stainless steel. Therefore, the

higher the nickel content, the more resistant the

stainless steel is to corrosion.

Stainless steel is a great alternative to teflon coated

aluminum cookware. However, on the stove or cook top,

stainless steel alone doesn't provide optimal heating

which is why pots and pans are generally made of tri-ply

construction. In the case of a stainless steel frying pan,

an aluminum core is sandwiched between two layers of

18/10 stainless steel allowing heat to distribute evenly

across the pan. In these pans the aluminum does not

react or come into contact with food at all.

Impact-bonded Triple-layer base to ensure even distribution of heat.

Stainless Steel

Products

Serving Dishes

Pots & Pans

Serving Dishes

BeverageServing Trays

Dessert and Fruit

Chafing Dishes

Various Items

Aluminum Products

Aluminum is a lightweight metal with very good thermal conductivity. It is resistant to many forms of corrosion. Aluminum

is commonly available in sheet, cast, or anodized forms, and may be physically combined with other metals.

Anodized Aluminum has had the naturally occurring layer of Aluminum oxide thickened by an electrolytic process to create

a surface that is hard and non-reactive. It is used for sauté pans, stockpots, roasters, and Dutch ovens.

Uncoated and un-anodized Aluminum can react with acidic foods to change the taste of the food. Sauces containing egg

yolks, or vegetables such as asparagus or artichokes may cause oxidation of non-anodized Aluminum.

Pot: How It Is Made?

1- LASER CUTTING OF S/S SHEETS USING MAZAK LASER CUTTING M/C

How does it work?

laser cutting is having mixture of gases excited enough

electronically by a power supply, that emits a light beam

that evaporates the material. This mixture of gases is mixed

with inert gas and pressurized to cut through the material.

And there’s an assist gas which is typically Argon, Nitrogen,

Oxygen to help get the material out of the way.

There’re also some risks with laser cutting, the beam could

reflect off of something potentially bounce through an area

that you aren’t intending for that laser to bounce through.

As far as blowing up, the gases that are used, the only thing

that is combustible could be oxygen... so if there would ever

be an oxygen leak, there’s some risk with that and it could

be flammable but the nitrogen or argon they are non-

flammable gases. The speed of the cutting depends on the

type of the material, the thickness.

Previously, the company used punching machines. Choosing between a punching or laser cutting machine is one of

the biggest challenges for manufacturers. There are, however, definite considerations to help determine when, and why,

punching will be the best technology to produce a part at the lowest cost for the customer and the highest profit for the

shop. Using a laser is often considered simpler than running a punching machine because only one tool, the laser beam

can create all shapes and sizes. But that flexibility comes at a cost. The initial equipment investment and the overall

operating costs are higher than those of a punching machine. When punching, there is really only one cost: the cost of

the electricity which is typically less than half of that required by the laser.

Another factor is production speed. A laser may be able to cut the holes in a part in 30 seconds, but the punch can

produce the same holes in about half the time.

The punch will most likely require more setup time than the laser. That’s where batch sizes come into play. If you need

to produce only one or two parts or a very small batch, the laser might be the more attractive approach because

changeover from one job to another will be faster. But as batch sizes increase, the savings of a few seconds per part add

up quickly and make punching the best alternative.

The thermal properties of the materials to be machined indicate that the machinability is enhanced for materials of low

thermal conductivity, diffusivity, and melting point.

TECHNICAL SPECIFICATIONS ABOUT MAZAK LASER CUTTING M/C

A- Laser gas is CO2 + H2

B- Assist Gas is N2

C- Laser generator and external optics require cooling, Water is a commonly used coolant, usually circulated through a

chiller or heat transfer system.

D- Power used is 4000 Watts, or 40000 volts

E- Exhaust unit

DATA INPUT

Mazak is a CNC M/C, so to get a different set of geometries from a rectangular sheet we should first draw the

geometry we need in AutoCAD and export it as DWG file, then enter it in a software that is integrated with the machine to

calculate the alterations and then get the G-Code, then we enter the G-Code to the machine, then we enter the parameters

of the cutting operations such as thickness, feed, power …etc. Then we push the start button.

Produced sheets from LBM operations

2- Deep Drawing Operations

Numerous variables affect the success of a deep-drawing process. Some are major and some minor, but you’ll need to take

all into consideration when designing, building, and troubleshooting a drawing operation.

I- Material:

The process of making coil material, whether ferrous or nonferrous, involves such variables as chemistry, time, and

temperature. So your process must be designed to accept the normal variation that will occur.

The six key mechanical properties to consider in any coiled metal are:

1. Tensile and yield strength.

2. N value, or work-hardening exponent.

3. R value, or plastic strain ratio of thickness to width.

4. Elongation percentage.

5. Metal type and gauge.

6. Topography or surface finish.

Each one of these properties affects the metal’s ability to flow and stretch in a deep-drawing operation.

II- Friction

Friction between the sheet metal and die is caused by many factors, but nothing affects friction in a drawing or

stretching operation more than the application of lubricant.

Hundreds of types of lubricants are used in metal stamping operations. Most have special additives that allow

them to change their frictional value with respect to heat

For example, chlorinated lubricants have a much lower coefficient of friction when heated to about 350 degrees F

than when cool. These lubricants are best suited to deep-drawing and forming higher-strength steels.

Other lubricants with additives include soap-based, oil-based, wax based, poly-based, fatty ester, and sulfurized

products. Synthetic lubricants also are available that change frictional values dramatically.

The tooling material also affects friction; for example, tools made from aluminum bronze typically have a much

lower coefficient of friction than tool steel dies. Tool steel coatings, die surface finish, and material topography also

affect the frictional value between the sheet material and the die and influence the amount of metal flow and

stretch that can be achieved.

Heat is another factor contributing to friction. As punches and dies warm up, they expand, resulting in smaller

clearances between working die sections. This change in clearances can cause ironing of the material. Insufficient

clearance can increase heat even more, which can break down the lubricant (depending on its additives) and cause

scoring, galling, and splitting. It’s a vicious cycle.

III- Forming Speed

Forming speed influences the amount of stretch and flow that occurs in a drawn or stretched part. Think of your

metal as putty: Pull it too fast and it breaks, but pull it slow and it stretches. When subjected to deep drawing,

metal behaves in a similar fashion.

Metal needs time to flow into the die. Once it begins to flow, the rate of flow can typically increase. Faster speeds

create more friction. More friction creates more heat. More heat can be good or bad depending on the metal type

and lubricant additives.

In general, for deep drawing, slower is better. This is the reason deep double sinks are not drawn in fast crank-

drive presses. In any case, changes in forming velocity affect the amount of strain and stress generated in the part.

This explains why using a different press to form a part often results in slightly different part geometries and

varying springback in strained areas.

IV- Die/Blank Geometry and Holding Pressure

While the topics of die and blank geometry and holding pressure are too broad to explain in great detail here, they

are very influential to the amount of flow and stretch in a metal and must be considered.

The main topics to keep in mind are:

• Drawing ratio (punch-to-blank relationship).

The draw ratio, the relationship between the size of the draw punch and the blank—is among the most

important elements to consider when attempting to deep draw a part. In fact, it is one of the main reasons that

so many stations are required to make tall, small-diameter parts. If the blank is too far from the punch, the

metal most likely will stretch and could fail. Reducing the blank size will cause the metal to flow.

• Blank-holding pressure.

When the pressure pad contacts the part, it forces the part to take the ideal shape.

• Part features and design.

• Part and die radii, size, and shape.

• Draw bead and draw bar geometries.

A draw bead is like a speed bump for the metal, it forces the metal to bend and unbend before flowing into the

cavities and over the punch. Increasing binder or draw pad pressure will exert more force on the material,

restricting flow. This helps reduce wrinkling and increase the amount of stretch in the part.

• Binder shape.

3- Blanking Process

Blanking is then used to cut the excess material that results from using the pressure pad to get the final shape of the pot, the

output of this process is scrap

4- Hydroforming Process

Cookware applications often demand parts with outstanding surface finishes so this process is introduced in some parts to

make a bulged shape.

HYDROFORMING ADVANTAGES

Inexpensive tooling costs and reduced set-up time.

Reduced development costs.

Shock lines, draw marks, wrinkling, and tearing associated with matched die forming are eliminated.

Material thinout is minimized.

Low Work-Hardening.

Multiple conventional draw operations can be replaced by one cycle in a hydroforming press.

Ideal for complex shapes and irregular contours.

Materials and blank thickness specifications can be optimized to achieve cost savings.

STEPS USED IN HYDROFORMING PROCESS:

5- Induction Furnace

We use it in steel cookware before getting it punched with an aluminum disc at its bottom, to make heat distributed

uniformly preparing it to the next step

6- Screw Press

We use Screw press/punch to bond a layer of Aluminum to the bottom of the pot to produce thereafter a three layered pot

bonded together (most often stainless steel and either aluminum or copper).

Stainless cookware is used for its durability, and ease of maintaining and cleaning the pan. The aluminum center core, clad

with stainless steel ensures your food will cook evenly. The magnetic stainless steel exterior enables the cookware to be

induction compatible, and perfect for use on all other heating sources available in kitchens today.

7- Spot welding of handles

Handles and knobs determine the comfort of working with cookware. Handles can be detachable, screwed on, riveted, or

spot-welded, but ones used in Zahran is spot-welded.

8- Gold/Silver plating and finishing

Gold plating solutions regularly come in 14-karat, 18-karat, or 24-karat gold. The color of the finished product may vary

depending on the karat levels.

Color may also vary when metal alloys, such as copper or silver, are added to the plating solution.

i- Mask the parts you don’t want to get plated with varnish.

ii- First clean the part to be plated.

iii- Put all pieces to be electroplated into an ultrasonic unit on hot temperature for 10 minutes.

iv- Steam clean pieces

v- Prepare electrocleaner solution.

vi- Rinse in clean distilled water.

vii- Use activating solution. No electricity is needed.

viii- Electroplate.

Thickness of gold or silver is about 1~2 microns depending on electroplating timing.

Plastic and Electrical Appliances.

INJECTION MOLDING OF THERMOPLASTICS AND THERMOSETS

No other process has changed product design more than INJECTION MOLDING. Injection molded products appear in every

sector of product design: consumer products, business, industrial, computers, communication, medical and research

products, toys, cosmetic packaging and sports equipment. The most common equipment for molding thermoplastics is the

reciprocating screw machine, shown schematically in the figure. Polymer granules are fed into a spiral press where they mix

and soften to a dough-like consistency that can be forced through one or more channels ('sprues') into the die. The polymer

solidifies under pressure and the component is then ejected.

Thermoplastics, thermosets and elastomers can all be injection molded. Co-injection allows molding of components with

different materials, colors and features. Injection foam molding allows economical production of large molded components

by using inert gas or chemical blowing agents to make components that have a solid skin and a cellular inner structure.

Process schematic:

Polymers

Thermoplastics

ABS (used in zahran)

Polypropylene PP (used in

Zahran)

Thermosets

Polysters

Phenolics (used in Zahran)

Epoxies

Injection molding is the best way to mass-produce small, precise, polymer components with complex shapes. The surface

finish is good; texture and pattern can be easily altered in the tool, and fine detail reproduces well. Decorative labels can be

molded onto the surface of the component (see In-mold Decoration). The only finishing operation is the removal of the

sprue.

TECHNICAL NOTES

Most thermoplastics can be injection molded, although those with high melting temperatures (e.g. PTFE) are difficult.

Thermoplastic-based composites (short fiber and particulate filled) can be processed providing the filler-loading is not too

large. Large changes in section area are not recommended. Small re-entrant angles and complex shapes are possible, though

some features (e.g. undercuts, screw threads, inserts) may result in increased tooling costs. The process may also be used

with thermosets and elastomers. The most common equipment for molding thermoplastics is the reciprocating screw

machine, shown schematically in the figure. Polymer granules are fed into a spiral press where they mix and soften to a

dough-like consistency that can be forced through one or more channels ('sprues') into the die. The polymer solidifies under

pressure and the component is then ejected.

PROPERTIES OF ABS (ACRYLONITRILE BUTADIENE STYRENE)

ABS (Acrylonitrile-butadiene-styrene) is tough, resilient, and easily molded. It is usually opaque, although some grades can

now be transparent, and it can be given vivid colors. ABS-PVC alloys are tougher than standard ABS and, in self-

extinguishing grades, are used for the casings of power tools.

Composition (summary)

Block terpolymer of acrylonitrile (15-35%), butadiene (5-30%), and styrene (40-60%).

The picture says a lot: ABS allows detailed moldings, accepts color well, and is non-toxic and tough enough to survive the worst

that children can do to it.

Recycle mark

ABS has the highest impact resistance of all polymers. It takes color well. Integral metallics are possible (as in GE Plastics'

Magix.) ABS is UV resistant for outdoor application if stabilizers are added. It is hygroscopic (may need to be oven dried

before thermoforming) and can be damaged by petroleum-based machining oils. ASA (acrylic-styrene-acrylonitrile) has very

high gloss; its natural color is off-white but others are available. It has good chemical and temperature resistance and high

impact resistance at low temperatures. UL-approved grades are available. SAN (styrene-acrylonitrile) has the good

processing attributes of polystyrene but greater strength, stiffness, toughness, and chemical and heat resistance. By adding

glass fiber, the rigidity can be increased dramatically. It is transparent (over 90% in the visible range but less for UV light)

and has good color, depending on the amount of acrylonitrile that is added this can vary from water white to pale yellow,

but without a protective coating, sunlight causes yellowing and loss of strength, slowed by UV stabilizers. All three can be

extruded, compression molded or formed to sheet that is then vacuum thermo-formed. They can be joined by ultrasonic or

hot-plate welding, or bonded with polyester, epoxy, isocyanate or nitrile-phenolic adhesives.

PROPERTIES OF POLYPROPYLENE (PP)

Polypropylene, PP, first produced commercially in 1958, is the younger brother of polyethylene - a very similar molecule

with similar price, processing methods and application. Like PE it is produced in very large quantities (more than 30 million

tons per year in 2000), growing at nearly 10% per year, and like PE its molecule-lengths and side-branches can be tailored by

clever catalysis, giving precise control of impact strength, and of the properties that influence molding and drawing. In its

pure form polypropylene is flammable and degrades in sunlight. Fire retardants make it slow to burn and stabilizers give it

extreme stability, both to UV radiation and to fresh and salt water and most aqueous solutions.

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Recycle mark

Standard grade PP is inexpensive, light and ductile but it has low strength. It is more rigid than PE and can be used at higher

temperatures. The properties of PP are similar to those of HDPE but it is stiffer and melts at a higher temperature (165 - 170

C). Stiffness and strength can be improved further by reinforcing with glass, chalk or talc. When drawn to fiber PP has

exceptional strength and resilience; this, together with its resistance to water, makes it attractive for ropes and fabric. It is

more easily molded than PE, has good transparency and can accept a wider, more vivid range of colors. PP is commonly

produced as sheet, moldings fibers or it can be foamed. Advances in catalysis promise new co-polymers of PP with more

attractive combinations of toughness, stability and ease of processing. Mono-filaments fibers have high abrasion resistance

and are almost twice as strong as PE fibers. Multi-filament yarn or rope does not absorb water, will float on water and dyes

easily.

PHENOLICS

Bakelite, commercialized in 1909, triggered a revolution in product design. It was stiff, fairly strong, could (to a muted

degree) be colored, and - above all - was easy to mold. Products that, earlier, were handcrafted from woods, metals or

exotics such as ivory, could now be molded quickly and cheaply. At one time the production of phenolics exceeded that of

PE, PS and PVC combined. Now, although the ration has changed, phenolics still have a unique value. They are stiff,

chemically stable, have good electrical properties, are fire-resistant and easy to mold - and they are cheap.

Phenolics are good insulators, and resist heat and chemical attack exceptionally well, making them a good choice for electrical

switchgear like this telephone and distributor cap. (Telephone image courtesy of Eurocosm UK.).

Recycle

Not recyclable!

Phenolic resins hard, tolerate heat and resist most chemicals except the strong alkalis. Phenolic laminates with paper have

excellent electrical and mechanical properties and are cheap; filled with cotton the mechanical strength is increases and a

machined surface is finer; filled with glass the mechanical strength increases again and there is improved chemical

resistance. Fillers play three roles: extenders (such as wood flour and mica) are inexpensive and reduce cost; functional

fillers add stiffness, impact resistance and limit shrinkage; reinforcements (such as glass, graphite and polymer fibers)

increase strength, but cost increases too. Phenolic resins have creep resistance, and they self-extinguish in a fire. They can

be cast (household light and switch fittings) and are available as rod and sheet. Impregnated into paper (Nomex) and cloth

(Tufnol), they have exceptional durability, chemical resistance and bearing properties. Phenolics accept paint,

electroplating, and melamine overlays.

References

1- CES EduPack

2- Different issues of Stamping Journal

3- www.thefabricator.com

4- Advanced Machining Processes, Hassan El-Hofy.

zahran - training final report

Engineering