zahran - training final report
TRANSCRIPT
Marwan Shehata Mohamed | Summer Training | August 20, 2016
Student Training Report PRESENTED TO TRAINING COMMITTEE
PAGE 1
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
PAGE 2
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
PAGE 3
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.
PAGE 4
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
PAGE 5
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.
PAGE 6
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.
PAGE 7
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:
PAGE 8
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.
PAGE 9
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.
PAGE 10
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
PAGE 11
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
PAGE 12
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.
_
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.
PAGE 13
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.