Change your life, this is the motto of PEL. PEL is a famous company in Pakistan which is famous for its Home appliances like, Refrigerator, Air conditioner, Microwave oven, Deep freezer, and water dispenser.Their R&D department is the best.

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INTERNSHIP REPORT
Pak Electron Limited
Submitted To:
HR PEL
Submitted By:
SABOORA KHATOON
Department:
Process & Planning
(From 22/06/11 to 11/07/11)
UNIVERSITY OF ENGINEERING
AND TECHNOLOGY, LAHORE

2. ACKNOWLEDGMENT
All the praises are for the almighty, Allah who bestowed me with the ability and
potential to complete this Internship. I also pay my gratitude to the Almighty for
enabling me to complete this Internship Report within due course of time.
I am really pleased here to acknowledge the sheer efforts of many people those
who have provided me their relentless services in the completion of my
Internship and my internship report. I would like to thank personally to the whole
staff of Process and Planning Department, who from there very busy schedule
helped me in many ways.
May Allah bless them all!
SABOORA KHATOON

3. Executive Summary:
Pak Elektron Limited (PEL) is the pioneer manufacturer of electrical goods in
Pakistan. PEL is a public limited company under the flag of Saigol group, one of
the top business groups of Pakistan. Saigol group has different companies in
different industries like textiles, sugar, power and electronics. PEL was established
in 1956 in technical collaboration with M/s AEG of Germany. In October 1978, the
company was taken over by Saigol Group of Companies. It has two divisions:
1. Power Division
2. Appliances Division
Appliances division has the products of Refrigerators, Air Conditioners, Micro
wave Ovens, Washing Machines, Diesel and Petrol Generators and Water
dispensers. The major products of appliances are refrigerators and air
conditioners and they have a variety of models and features.
I had my internship in appliances division, as I am student of mechanical
engineering, so I got a thorough study of the processes in this section, designing,
manufacturing, assembling and finally testing and packing. Being an internee in
process & planning department, I was assigned to work on improving the process
of thermoforming and paint plant shop. However, small overview of other
departments was also given.

4. Thermoforming of Cabinets
Refrigerator’s inner cabinet is formed by a vacuum forming machine. Vacuum
forming machine consists of reduction plate, counter frame, bubble photocell,
PLC controller and sixty heaters of 650 watts.
In PEL, there are 6 thermoforming machines that are being used to produce good
quality cabinet liners for all the different refrigerator models.
Materials:
For this purpose two types of plastic sheets are being used:
1. Acrylonitrile butadiene styrene (ABS)
2. High Impact Polystyrene (HIPS)
Process:
There are a maximum of two workers at each machine. One worker feeds the
sheet in to the thermoforming machine. The sheet is held in place by a frame and
then heated to forming temperature by 2 ceramic heaters. One ceramic heater is
placed above the sheet and one below. The temperature of the heaters is kept at
450°C.
Air is then blown on the molten sheet from below to form a bubble. Then the
mould is raised and the bubble is allowed to set on the mould. Air is vacuumed
out of the mould to ensure that the plastic sets according to the profile of the
mould. The formed cabinet is demoulded by blowing air on to it and the mould is
removed.
The worker unloads the formed cabinet and transports it to a work table where
he uses a knife to trim the edges. The cabinet is now ready for punching.

5. Cycle Time:
Thermoforming machines using such ceramic heaters generally have a cycle time
of 150 to 180 sec. On average 3 cabinets are made every 5 minutes.
Problems:
The following problems are encountered during peak production season:
 A rejection rate of approximately 5%
 50% due to moisture accumulation on sheets because of humid work
environment
 20% due to machine malfunction
 30% due to human negligence
 High power consumption
 High running costs
Suggestions for process improvement
Moisture Control
Moisture accumulation is a big problem in the storage of the sheets during humid
weather conditions and is a major cause of rejection of thermoformed cabinets.
Large bundles of sheets can be vacuum packed using external sealers. Vacuum packing
is a method of packaging that removes air from the package prior to sealing. It
minimizes the chances of moisture accumulating on the packed sheets.
Another option is the use of bags of silica gel as silica is known to be a good absorber of
moisture. These bags can be very useful during storage of sheets as dehumidifying
agents.

6. Preventive Maintenance
Preventive maintenance is a schedule of planned maintenance actions aimed at the
prevention of breakdowns and failures. The primary goal of preventive maintenance is
to prevent the failure of equipment before it actually occurs. It is designed to preserve
and enhance equipment reliability by replacing worn components before they actually
fail. Preventive maintenance activities include equipment checks, partial or complete
overhauls at specified periods, oil changes, lubrication and so on. In addition, workers
can record equipment deterioration so they know to replace or repair worn parts before
they cause system failure.
Currently, in thermoforming section breakdown maintenance is being practiced which
results in form of losses, unpredictable machine malfunctions and prolonged machine
shutdowns. Preventive maintenance practices will help to reduce these factors.
Ceramic vs. Halogen Heaters
Ceramic Infrared heaters normally need 15-20 min heating up time to reach full
intensity; some can manage it in 5-10 min.
In Halogen heaters the heat is transmitted mainly by radiation and only secondary by
gas molecule pulses.
The radiation efficiency, the ratio between the consumed electrical energy (kW) and
radiation energy produced by the h eaters, is as following:
Type Radiation
Efficiency
Radiation maximum
at
Heating time
reduction
Ceramic IR elements 8-10% 3.5 μm 0
Halogen Flash 18-22% 1 μm 55-57%
The radiation efficiency is already a quite significant factor for the factory electricity bill
and the cost of Thermoformed piece. More relevant is that the ceramic infra-red

7. elements need 10-20 min to reach their maximum efficiency, so that they have to be
permanently on, even when no heating is needed.
While some IR heaters are reduced to 5% intensity during stand-by to save only by this
way about 45% of their energy consumption (plus the a.m. radiation efficiency, minus a
small extra start-up consumption) and the halogen lamps are just switched on and off
each time when they are needed. Some new, faster reacting ceramic heaters are used
from some companies, which allow a partial regulation of intensity inside a work cycle,
but often they get this regulation only by reducing the radiation efficiency during heat
up.
Halogen “Flash” lamps with 50%-57% less heating time. The flash lamps reduce the
heating time to 55-57% less in comparison to IR ceramic elements because the shorter
waves can surpass a thicker surface layer of the sheet as IR light with longer waves and
therefore more energy can be passed to the sheet without burning the surface. This in
addition safes time (50% of heating time and about 25% less cycle time in a single
station thermoformer), increases the capacity and reduce strongly energy costs (more
absorption and less reflection). Because of this heating time reduction a single station
thermoformer with these halogen lamps are as fast as a line with 1 pre-heater using
standard IR ceramic elements.
Size of heaters: The smaller the heater sizes, the better heat intensity on different
surface areas can be distributed according to needs and by this way the losses on sheet
peripheral cuts can be reduced, even to cut-less sheets in some cases.
Servo Motors
Speeds of mechanical movements are only a small portion of process time and it does
not differ significantly between the a.m. producers inside each line group – with one

8. exception: using fast NC-controlled servomotors instead of electromechanical and
pneumatic movements, speeds up movements by 20-30% - representing 5-7 % of cycle
PAINT PLANT
In this section refrigerator and deep freezer components are painted by
Corona Gun.The paint being used is of Juton Company and is in powdered
form. First the components needed to paint are loaded on hooks in
conveyor then inspection is performed to identify any dent or defect. After
that steps involved are as follows:
 Treatment line:
In this components are treatment is done to remove oils, greases, forming
compounds, lubricants, coolants, cutting fluids, and other undesirable
organic and metallic residue left behind as a result of fabrication.
 Degreasing:
For this purpose vapour de-greasing is done.This process is a closed system
in which the item to be cleaned is exposed to the condensing vapours of
the solvent.This method effectively removes light oils/greases.
 De-rusting:
After removal of the organic and metallic residues, the parts are placed into
the appropriate passivation solution. Passivating Solution is phosphoric acid
based solution. The purpose is the removal of exogenous iron or
contamination from the surface of a stainless steel by means of a chemical
dissolution.
 Water rising:
After that the parts are rinsed with water.
 Activation process:
This process provides fine active crystal centres on the surface of the metal
which ultimately results into tine phosphate coating Layer in phosphating
stage.This process helps to attain a uniform phosphate coating.There are
two types of activation processes:

9. 1) Acidic activation
2) Basic activation
 Air blowing:
Air pressure is given to clean the parts.
 Drying oven:
Parts are dried at45°C and finally are ready to be painted.
 Painting booth:
The parts pass through a painting booth. Here, automatic and manual
powder paint guns deliver a constant, electrostatically charged mist of
powder coat. powder coat is applied to a thickness spec of3 mils.
 Baking:
After the powder coat has been applied, the parts move on to oven where
they are baked at 220°Cdegrees for one hour.
Suggestions for process improvement
Hangers New Design
 Hangers for Latches
Total width = 46cm
Distance b/w 2 hooks = 5cm
Hangers in each row = 8
No. of rows = 10
Distance b/w 2 rows = 12cm
Total height = 127 cm
Capacity of each hanger = 80
Distance b/w 2 hangers on conveyor = 82 cm

10. Our recommendations:
1. We can increase the width of hanger up to 60cm which means 2
hooks per row will be added as there are total 10 rows. Then
Increase in capacity would be = 20
Suppose capacity of conveyor to carry hangers is 150 hangers at a
time then
Total increase in capacity = 150 x 20 = 3000 per cycle
2. By decreasing the distance b/w 2 hangers by 2cm a total of 20cm will
be free in the hanger of same height allowing us to add 2 more rows of 10
hooks each.
Total increase in capacity per hanger by this would be = 20.
But this might cause the hook to over load or cramp.
Total weight carrying capacity of each hanger is 10 kg. And Total weight of fully
loaded hanger is 3-4kg. so to utilize the complete capacity, we propose to
increase the production by attaching 2 hangers through a 6inch or 15cm
connecting rods, so the hanger don’t collide with each other during the complete
operation. In this way the total production capacity of the whole cycle will be
doubled.
 Hangers for Latches:
Total width = 60cm
No. of rows = 10
Hangers in each row = 8
Distance b/w 2 rows = 16cm
Total height = 122cm
Capacity of each hanger = 56
Distance b/w 2 hangers on conveyor = 82 cm
Distance b/w 2 hooks = 7cm

11. Our recommendations:
Same method of attaching 2 hangers together can be used to increase
production as described previously.
Since according to paint plant supervisors, we cannot increase the width or
height of the hangers as there is a problem of clearance in oven and unit
where washing and phosphate is being done so to change hanger’s width
and dimensions, we’ll also have to increase the size of oven.
Distance b/w the two rows of these hangers cannot be changed as well
because its already standardized according to the size of the components.

12. Pre-assembly
This section is for refrigerator pre assembly. PEL’s refrigerators are available in
different colors, models, prices and capacities.
These are as follows:
1. Xpression Series
2. Premier Series
3. 6-Series
4. Delux Series
5. Smart Series
6. Mini Series
Process:
The first step is bending of Aluminum sheet and then copper coil is coiled around it
and side plates are fixed. Copper wire has a thickness of 5×16mm. After that
freezer frame, freezer support and cabinet support is assembled.6-8 bottles of
eutectoid fluid are placed to keep the freezer cooled for longer time when the
power supply is turned off. Meanwhile base assembly and anticondensate pipe are
prepared.
After preparation these parts are assembled. Condenser, evaporator, expansion
tube etc are added. These are joined through soldering. Then back plate, back
panel, side panel and top panels are assembled. The next step is foaming to make
refrigerator body more rigid. The material used for foaming is polyol, isocyanate
and cyclopentane as blowing agent.
In winter season cabinet is heated before foaming because the process of foaming
needs high temperature.
After foaming, eight is measured, weight tolerance is 300grm. Then whole unit is
tested for 24hours with thermo sensor, plc operated, with constant supply of
heaters. Unit is OK if reaches temperature -28°C.

13. Door assembly & Foaming
In this section refrigerator and deep freezer doors are assembled. The first step is
fixing end cap and concede handle. Then gaskit fitting and after that foaming is
performed. The material used for foaming is iso-cyanate and pylol. Then lock
assembly is done and finally the doors are dispatched to the relevant assembly line.
Foaming Machine:
According to the invention, a metered quantity of a foamable mixture is fed into
the gaps between the inner and outer walls of a cabinet or door, placed in a
foaming jig; the foaming process is controlled by sensing characteristic parameters,
for example, the temperature of the jig, cabinet or door, or the pressure of the
foaming plastic material, comparing them with reference parameters or data
stored in a data processing unit.. The metered quantity of mixture fed in each
subsequent foaming operation is corrected each time according to the changes in
the peak pressure of the foam with respect to the previous foaming operation. On
cooling, it turns to hard solid form connecting all parts rigidly.

14. Gaskit Extrusion
Here gaskit for deep freezer and refrigerator doors is made through extruder.
Process:
On the extrusion line Polyvinylchloride grains are sucked through vacuum
system into the hopper of the extruder. Then these are melted by heaters and
are passed through T- Die. The desired gaskit is cooled for its shape retention.
After that it is pressed for getting compact shape. Then Auto sensors are there
which cut the desired length of gaskit and after that magnet is passed through
refrigerator gaskit and finally it is dispatched to deep freezer and refrigerator
doors assembly.
Plastic Injection Molding
Injection molding is the most common method of part manufacturing. It is ideal
for producing high volumes of the same object.[5] Some advantages of injection
molding are high production rates, repeatable high tolerances, the ability to use
a wide range of materials, low labor cost, minimal scrap losses, and little need
to finish parts after molding. Some disadvantages of this process are expensive
equipment investment, potentially high running costs, and the need to design
moldable parts.
A.B.S Material is dried at 75°C, it can vary with the type of material.
Injection molding cycle:
The sequence of events during the injection mold of a plastic part is called the
injection molding cycle. The cycle begins when the mold closes, followed by the
injection of the polymer into the mold cavity. Once the cavity is filled, a holding
pressure is maintained to compensate for material shrinkage. In the next step,
the screw turns, feeding the next shot to the front screw. This causes the screw
to retract as the next shot is prepared. Once the part is sufficiently cool, the
mold opens and the part is ejected.

15. Dies & Molds
Dies & molds are used to manufacture identical items in large quantity. Drafts
man makes drawings using Del CAM software after approval from research &
development department. Then machining process starts using planner, shaper,
drilling, lathe, EDM and CNC machining centre. NC program is transferred to CNC
machine through card. After this parts are assembled to make dies & molds.
Dies are used for sheet metal and molds for injecting molten material.
Condenser Section
In this section condenser for refrigerator is manufacture. The raw material is cold
rold and bundy tube. Louver is prepared at louver press machine then spot
welding is performed to join bundy tube and louver. After that air stripping is
done and finally cap fixing. The control of spot welding machine is pneumatic.
Plastic Sheet Extrusion
Plastic sheet for refrigerator inner cabinet and deep freezer door is extruded in
this section. This is totally automated plant.
Process:
Raw material HIPS in the form of small beads is mixed with colour master batch
M- 36 prior to the hopper. Then it is transferred to storage chamber, from storage
chamber it sucked into extruder Hopper through auto loader. After that material
is dried in the hopper and travels in the barrel along with screws. During this
three independent PID controlled heater zones gradually increase the
temperature of the barrel from 175-210 C0.The material is melted and is extruded
into sheet through T-Die. After that it passes through roller unit around which
water circulates and it is cooled and stretched. Then passes through cutting unit
and is cut into desired length. After that sheet is transferred to conveyor and
finally unloaded for storage. Thickness of sheet for refrigerator cabinet is4.7 mm
while for deep freezer door is 2.25mm.

16. Quality Control
There are four divisions Market quality, Process quality, Techniques, Incoming
quality control. All subassemblies of tubing that will contain refrigerant are
pressure-tested with nitrogen, which will reveal any flaws in the tubing and in the
soldering that joins it. The entire unit is also leak-tested prior to charging with
freon. Once charged, the unit is tested as a whole to ensure that it is capable of
reaching design temperatures including those necessary during the defrost cycle.
The unit is operated with sensors inside that determine the temperature changes
over time. Sometimes the refrigerant pressures are also measured. The unit is
then subjected to a final 'sniff test by a machine that detects refrigerant to ensure
that no leaks have developed during testing.
Research & Development
This department has designer, vendor development and marketing. R & D
contributes for changes in existing model and addition of new features. For this
purpose market survey is conducted. When there is need to make changes or add
new features. Feasibility study is done whether production equipment, labor and
capacity is available. After these considerations the new model is designed by the
designers. The new design is verified and a sample is prepared. Then sample is
validated. After successful validation bulk production is started.

17. Press Shop
Press working may be defined as, a manufacturing process by which various
components are made from sheet metal. This process is also termed as cold
stamping. The machine used for press working is called a press.
It is the process involving the cutting, forming and the drawing of the metal
sheets using a punch and a die. In cutting of sheet metals, “shear forces” are
applied on the metal. These
processes are generally carried out
at room temperature.
The pressure applied by the punch
and the die is the shear stress;
resistance to this stress is called
shear strength. In order to cut the
metal sheet, the shearing stress must
be greater than the shear strength.
Press machine
The main features of a press are:
 A frame which supports a ram or a slide and a bed, a source of mechanism
for operating the ram in line with and normal to the bed.
 The ram is equipped with suitable punch/punches and a die block is
attached to the bed.
 A stamping is produced by the downward stroke of the ram when the
punch moves towards and into the die block.
 The punch and die block assembly is generally termed as a “die set” or
simple as the “die”.

18. These tools are necessary for the various processes including forming, ironing,
punching, blanking, slotting and many other operations that use press working
equipment.

19. Press Working Operations
The sheet metal operations done a press may be grouped into two categories.
1: Cutting operations
2: Forming operations
 In cutting operations the work piece is stressed by its ultimate strength.
The stresses caused in the metal the applied forces will be shear stresses.
The cutting operations include:
(a) Blanking (b) Punching (c) Notching
(d) Perforating (e) Trimming (f) Shaving
(g) Slitting (h) Lancing
 In forming operations, the stresses are below the ultimate strength of the
metal, in this operation, there is no cutting of the metal but only the
contour of the work piece is changed to get the desired product.
The forming operations include:
(a) Bending (b) Drawing (c) Squeezing
Computational capacities and tonnage requirements
 Smallest hole that can be punched
 Clearance in die and punch
 Die block design
 Punch design
 Cutting force
Presses are given tonnage rating which is expressed as the “energy expanded on
the work at each stroke of the press must equal the tonnage required times the
distance through which the tonnage must act”.
The tonnage is also limited by the motor restrictions.

20. Part Processing
In press shop various parts of the refrigerator are being processed according to
their required design. These parts include Freezer door, Refrigerator door, Side
panel, Back panel, Top panel, Cabinet base (loom),Upper, lower and central strips,
latches and many other parts .
Material Processing
In press shop, the material is received in the form of coils. These coils are then
decoiled and passed to shearing machine where large sized metal sheets are
being cut. This process of decoiling is done manually but automatic decoiler can
also be utilized. There are three types of metal sheets being processed.
 CR sheets (cold roll)
 GI sheets ( galvanized iron)
 VCM sheets (vinyl coated metal)
In press shop, there are total of 49 press machines including 6 new high tonnage
capacity presses especially implemented for the new model DESIRE. The presses
are according to the tonnage.
 Small presses or C-type pneumatic presses have capacity of 25 to 50 tons.
 Large presses or H-type hydraulic presses have capacity of 160 to 200 tons.

21. Process Improvements
The press shop is fully crowded with presses of all kinds. The varieties of parts are
being processed here step by step. The presses are usually manually loaded and
unloaded. The part is processed and then after complete steps it is unloaded.
During the peak season, press shop can produce parts of almost 1700 refrigerator
units.
When the shape of blank to be cut is irregular, the summation of shear force
about the centre line of pressure may not be symmetrical due to this the bending
movements will be introduced in press ram producing undesirable deflection and
misalignment.
To avoid this centre of pressure must be calculated while laying punch position on
punch holder.
Critical stages in shearing action of metal are:
 Plastic deformation
 Penetration
 Fracture
While shearing the metals, the cutting edge must be sharp enough that it can tear
the part off on first stroke otherwise this can increase the rejection rate.
Economic stock utilizations of high importance a design engineer should aim for a
goal at least there must be 75% stock utilization.
In preparing layout it should be observed that the distance between nearest two
points of blank and between blanks and also edge of sheet to first blank in no
case be less than sheet thickness.