Introduction,Purpose,Injection Molding,Process Cycle,Injection Machine,Products of Injection Molding,Identification and chemical properties. The purpose of the industrial training is to provide exposure for the students on practical fields. Through this exposure, students will have better understanding of practice in general and sense of frequent and possible problems. This training is part of the learning process which exposes to uplifts the knowledge and experience of a student needs to be properly documented in the form of a report.

1. SUBMITTED BY
AADRSH KUMAR TIWARI
M.Sc. (POLYMER CHEMISTRY)
DAC, BBAU, LUCKNOW-226025
Enrollment number: - 175/16,
Roll number: - 131021
Presentation on
Injection Molding & Testing

2. 1. Introduction
2. Purpose
3. Injection Molding
4. Process Cycle
5. Injection Machine
6. Products of Injection Molding
7. Identification and chemical properties

3. 1. Introduction:
• This training is provide experience to the students about
the skill development in the field of polymer chemistry
which will be provide a skill for future carrier.
• Our training runs for four weeks.
• I have visited to Processing and Testing Section of
Polymers, CIPET, Lucknow for industrial training.
• During this training, I got the opportunity to gain
knowledge in industrial field of polymer chemistry.

4. •The purpose of the industrial training is to provide
exposure for the students on practical fields.
•Through this exposure, students will have better
understanding of practice in general and sense of frequent
and possible problems.
•This training is part of the learning process which
exposes to uplifts the knowledge and experience of a
student needs to be properly documented in the form of a
report.
2. Purpose:

5. 3. Injection Molding:
•Injection molding is the most commonly used
manufacturing process for the fabrication of plastic parts.
•The injection molding process requires the use of an
injection molding machine, raw plastic material, and a
mold.
•The plastic is melted in the injection molding machine and
then injected into the mold, where it cools and solidifies
into the final part.

6. •These housings are used in a variety of products including
household appliances, consumer electronics, power tools,
and as automotive dashboards.
•Other common thin-walled products include different
types of open containers, such as buckets.
•Injection molding is also used to produce several
everyday items such as toothbrushes or small plastic toys.
•Injection molding is used to produce thin-walled plastic
parts for a wide variety of applications, one of the most
common being plastic housings.

7. Clamping:
•Prior to the injection of the material into the mold, the two
halves of the mold must first be securely closed by the
clamping unit.
•Each half of the mold is attached to the injection molding
machine and one half is allowed to slide.
•The hydraulically powered clamping unit pushes the mold
halves together and exerts sufficient force to keep the mold
securely closed while the material is injected.
The process cycle for injection molding is very short,
typically between 2 seconds and 2 minutes, and consists of
the following four stages:
4. Process cycle:

8. Cooling:
•The molten plastic that is inside the mold begins to cool as
soon as it makes contact with the interior mold surfaces.
•As the plastic cools, it will solidify into the shape of the
desired part.
Injection:
•The raw plastic material, usually in the form of pellets, is fed
into the injection molding machine, and advanced towards the
mold by the injection unit.
•During this process, the material is melted by heat and
pressure.
•The molten plastic is then injected into the mold very quickly
and the buildup of pressure packs and holds the material.

9. •However, during cooling some shrinkage of the part may
occur.
•The mold cannot be opened until the required cooling time
has elapsed.
Ejection:
•After sufficient time has passed, the cooled part may be
ejected from the mold by the ejection system, which is
attached to the rear half of the mold.
•When the mold is opened, a mechanism is used to push the
part out of the mold.
•Force must be applied to eject the part because during
cooling the part shrinks and adheres to the mold.

10. Figure 1: Injection molded part

11. 5. Injection Machine:
• Injection molding machines have mainly two unit:-
•Injection unit
•Clamping unit
Injection Unit
•The injection unit (fig. 2) is responsible for both heating
and injecting the material into the mold.
•The first part of this unit is the hopper, a large container
into which the raw plastic is poured.
•The hopper has an open bottom, which allows the material
to feed into the barrel.
•The barrel contains the mechanism for heating and
injecting the material into the mold.

12. •A reciprocating screw moves the material forward by both
rotating and sliding axially, being powered by either a
hydraulic or electric motor.
•While it is advanced, the material is melted by pressure,
friction, and additional heaters that surround the
reciprocating screw.
•The molten plastic is then injected very quickly into the
mold through the nozzle at the end of the barrel by the
buildup of pressure and the forward action of the screw.
•Once the material has solidified inside the mold, the
screw can retract and fill with more material for the
next shot.

13. Figure 2: Injection molding machine - Injection unit

14. Clamping Unit
•Prior to the injection of the molten plastic into the mold, the
two halves of the mold must first be securely closed by the
clamping unit (fig. 3).
•When the mold is attached to the injection molding
machine, each half is fixed to a large plate, called a platen.
•The front half of the mold, called the mold cavity, is
mounted to a stationary platen and aligns with the nozzle of
the injection unit.
•The rear half of the mold, called the mold core, is mounted
to a movable platen .

15. •After the required cooling time, the mold is then opened by
the clamping motor.
Figure 3: Injection molding machine - Clamping unit

16. Figure 4: Injection molding machine

17. 6. Products of Injection Molding:
•Toothbrush
•Bottle
•Mug
•Tub
•Camode
•Bucket
•Hanger
•Fan blade
•Droll
•Tank cover
•Tempo head
•Mirror frame
•Dust pad
•Saddle
•Suitcase
•Mango harvester
•Baby chair
•Bottle cap
•Toys
•Double color plate
•Exausght

18. 7. Identification and chemical properties:
Identification by simple method:
Stage1: Look at the sample:
•The color of the plastic will give you some information.
•Some polymers have restricted color ranges, particularly the
thermosetting types.
Stage 2: Feel the sample:
• Few times you will start to get the feel for various
plastics.
• The poly-olefins have a very distinctive feel and you can
generally tell if it is one of them.
• The presence of glass fibre or other reinforcement
materials can change the feel and stiffness of the sample
but you can sometimes tell by the feel if there is
reinforcement present.

19. Stage 3: Cut a thin sliver from the edge of the sample:
• The first test is to cut a small sliver off the sample.
• This tells you a lot about the type of plastic you are trying
to identify.
Cutting tests:
•If a shaving can be pared off with knife, it may be a
thermoplastic. (note: PMMA & Polystyrene are brittle and
difficult to pare)
•If the material is rigid and will not pare off instead flakes
of powders, it may be probably a thermoset plastic.
•Scuff the sample with your fingernail.
•If scuff with fingernail- Urea formaldehyde resin.
•If does not scuff with fingernail- Malamine formaldehyde
resin.

20. Hot rod penetration test:
•Heat an electronic soldering iron to red hot and press against
the unknown sample.
•If the plastic material softens, and the rod penetrates, the
sample is thermoplastic.
•If the plastic material does not soften and the rod does not
penetrate, the sample is thermoset plastic.
Flotation test:
•This test will give the idea to distinguish the material
according to their density.

21. Floats on types
of plastics
Alcohol Vegetable oil Water Glycerin
PET No No No No
HDPE No No Yes Yes
PVC No No No No
LDPE Yes No Yes Yes
PP Yes Yes Yes Yes
PS No No No Yes
Table1: Flowing character of polymers

22. Plastics Bending behavior
1. Polythene Bends, tend to remain
2. Polypropylene Unbends most of the way
3. Polystyrene Cracks but retains bend
4. ABS Bend tends to remain
5. PVC(rigid) Bend easily & springs back quickly
6. PMMA Cracks and splinters
7. Nylon Difficult to bend, springs back
8. Polycarbonate Tough to bend
Bending tests:
•Some plastics will exhibit particular characteristics in the
manner in which they respond to bending behavior of some
plastics of almost same cross-section is given in Table 2.
Table 2: Bending behavior of plastics:

23. Metallic sound Dull sound
PS, HIPS Cellulosic’s
ABS Polyamides
PC, PPS PTFE, PMMA
PPO Polyacetal
Polysulphone PVC, Polyolefin’s
Dropping test:
•When a polymer molded component is dropped on hard
surface, it creates sound, which shall be either metallic sound
or dull sound.
•On the basis of sound polymer is distinguished in two
categories, which is tabulated in the Table 3.
Table 3: Sound characteristic of polymer:

24. Degree of
flammability
Burns
Self extinguishing Does not burn
Color of flame Yellow & orange; Blue; blue with yellow edges;
clear, orange, green etc.
Type of flame Steady; tall; short; sputtering
Smoke None; black; thin & thick black with sooty
streamers
Melt behavior Softens, remains hard, flows, bubbles, swells,
does not char but melt, melt & char
Burning test:
• A sample is held in flame.
• If it ignites without it from the flame a distance of flame.
• Makes observations as listed below & record the
observations, shown in below:
Table 4: Different observation during burning test

25. Thermo
Plastics
Melting Behavior Color of flame/kind of
smoke
Odor/smell
PE Melt & bubbles fiercely
around the edge, drips
Blue with yellow tip Waxy (burning
candle)
PP Becomes soft, tends to form
a ball, drips
Yellow with blue base Waxy smell,
lubricating oil
smell
PS/SAN Melt & bubbles around the
edge, spurting, burns readily
Orange- yellow, heavy
black sooty smoke
Marigold, strong
smell of styrene &
burning rubber
PVC Soften & forms a ball, chars
at bottom, self extinguishing
Yellow with green
bottom edge, some
white smoke
Chlorine smell,
pungent
Nylon Melts round edges & chars,
forwards formation drips
Blue with yellow tip Burning hair/
wool/vegetarian
PET/PBT Melts, opacifies, blackens,
molten material drips
Yellow, slightly smoke Pleasant elusive
odor
Table 5a: Typical results of burning test of polymers (thermoplastics)

26. Thermoset Color of flame/kind of smoke Smell
Phenolic resin Yellow flame, self extinguishing, some smoke
sparks
Charcoal smell
Urea resin Yellow with light blue edge, self extinguishing Fishy smell
Polyester resin
(unsaturated)
Burn with orange yellow flame, black smoke Ester smell
Epoxy Yellow flame, black smoke Charred flour smell
Elastomer Color of flame/ smoke
flame & kind of smoke
Smell Characteristics
Poly butylenes Yellow, blue base smoky Disagreeable, sweet Chars readily
Styrene-butadiene Burns continuously
yellow sooty
Sharp smell of
styrene
Chars readily, dry
powdery
NBR Yellow sooty Unpleasant Tacky
Polyisoprene (NR) Yellow sooty Strong smell like
burn rubber
Chars & readily
Table 5b: Typical results of burning tests of polymers (thermoset)
Table 5c: Typical results of burning tests of polymers (Elastomer)

27. 8. Chemical test:
Copper wire test:
•Take the piece of copper wire about 5 mm long. Push on end of the
wire in to a small cork. The cork is used as a handle so you are not
touching a hot wire.
•Place one pellet or plastics sample near your Bunsen burner. This is
the sample you will be testing.
•Hold the free end of the copper wire in the burner flame until it is red-
hot and the flame no longer has a green color.
•Remove the wire from the flame and torch the hot wire to the plastics
pellet or sample you will be testing. A small amount of the plastics
should melt onto the wire. If the wire sticks to the plastic sample, use a
pair of tongs to remove it.
•Place the end of the wire, with small amount of plastic on it, into the
flame. You should see a slight flash of a luminous flame (a yellow-
orange color). If the flame turns green in color, then sample contains
chlorine.

28. Melt flow index (MFI) test:
•Melt flow index is a measure the easy flow of melt of the
thermoplastic polymer.
•It is defined as the mass of the polymer (gm) flowing in 10 minutes
through a capillary of a specific diameter and length by a pressure
applied via prescribed alternative gravimetric weight for alternative
prescribed temperature.
•ASTM- D1238 & ISO-1133.
Test procedure:
•Melt flow test condition- Temp. 190oC, 10 kg, 5.5 min. pre heat, 20
cc of sample, diameter of die is 2.1 mm.
•Remove piston & die from barrel, clean it carefully (use die cleaner
& cotton).
•Then clean the barrel chamber through a duster & barrel cleaner
rod.
•Clamp the die carefully.

29. •Then put the hopper at the top of barrel chamber & fill the sample.
•Fit the piston in barrel and put on a specific load.
•Set the time cycle (sec.) & then after each cycle cut off the flow of
sample.
•Depending upon the resulting flow rate, a slightly shorter (10 sec.)
or longer cut (4 min.) may be substituted for the normal (1 min.) cut
weight the extrudate & multiply by the appropriate factor to obtain
the standard (gms/10min.) melt flow value.
S.N. Weight of cut off extrudate (LLDPE) in gm
1 0.0748
2 0.0730
3 0.0696
4 0.0725
5 0.0721
6 0.0757
Total 0.4373
Average (x) Total/6= 0.0729
•LLDPE:

30. = 0.0729 gm, MFI=
(Where; x= average weight & 10= cut off time cycle (sec.) & 600=
specific time in second).
MFI = = 4.374 gm/10 min.
MFI tester at CIPET, Lucknow

31. Density test: (ASTM-D792)
Methods: 1) Double density gradient column
2) Sinker method
3) RD bottle method
4) Bulk density method
5) Burette method
1) Sinker method:
•If density of polymer sample isles than water then we use butane-2-al.
otherwise water are used.
•The sinker part poured in water.
•Reading should be set zero again & again.
Example: we using PVC pipe sample for eliminating density.
Standard density of PVC is 1.40-1.46 gm/cm3
.

32. For sample 1:
Sample weight in air (W1) = 3.8697gm.
Sample weight loss in liquid (W2) = 2.6785 gm.
D = = 1.444 gm/cm3.
For sample 2:
Sample weight in air (W1) = 3.7507 gm.
Sample weight loss in liquid (W2) = 2.5959 gm.
D = = 1.444 gm/cm3.

33. Figure: Sinker method density measures by Mettler AE200