1. INJECTION MOLD DESIGN PDT 317
PREPARED BY: EN. SHAYFULL ZAMREE BIN ABD RAHIM
( )

2. COURSE CONTENT & COURSE OUTCOMES
PDT INJECTION MOLD DESIGN
COURSE CONTENT & COURSE OUTCOMES
Study
Week
Course Content
1 – 2
CHAPTER 1: Introduction to Plastic Technology
DEFINE and EXPLAIN the basic terminology process flow in plastic injection molding; EXPLAIN the differentiate type of mould, EXPLAIN, REVIEW and REPEAT the detail about injection molding machine.
CO1: Ability to “define” and “describe” basic
terminology process in plastic injection
molding and mould design.

3. INJECTION MOLDING PROCESS
PDT INJECTION MOLD DESIGN
INJECTION MOLDING PROCESS
What is Injection Molding Process???
A process that utilizes melted plastics injected into steel or aluminum molds which ultimately result in finished production parts.
Method of forming a plastic to the desired shape by forcing the heat softened plastic into a relatively cool cavity under pressure.
Manufacturing process where plastic is forced into a mold cavity under pressure.

4. PDT 317 - INJECTION MOLD DESIGN
PLASTIC POLYMERS
The word “polymer”
is a combination of
the Greek words:
“poly" which means
"many“ and “mer”
which means “part”
The basic structure
of a polymer
molecule can be
visualized as a long
chain of repeating
units

5. Polymers’ Classification
PDT INJECTION MOLD DESIGN
Polymers’ Classification
Thermoplastics:
The word “thermoplastic” is a combination of the Greek words: “therm" which means “heat“ and “plastikos ” which means “capable of being molded”
Once the polymer is formed it can be heated and reformed over and over again (allows recycling)
Thermosets
The word “thermoset” is a combination of the Greek words: “therm" which means “heat“ and “sets” irreversibly when heated
Therefore, can not be remelted. Once these polymers are formed, reheating will cause the material to degrade

6. PDT 317 - INJECTION MOLD DESIGN
PLASTIC MATERIALS

7. PDT 317 - INJECTION MOLD DESIGN
PLASTIC MATERIALS

8. INJECTION MOLDING MACHINE
PDT INJECTION MOLD DESIGN
INJECTION MOLDING MACHINE

9. INJECTION MOLDING PRODUCTS
PDT INJECTION MOLD DESIGN
INJECTION MOLDING PRODUCTS

10. INJECTION MOLDING MACHINE
PDT INJECTION MOLD DESIGN
INJECTION MOLDING MACHINE
The pellets are fed into heated cylinder and the melt is forced into the mold by hydraulic plunger or rotating screw of an extruder.
Barrels are heated externally to promote melting of the polymer.
The reciprocating screw will move backwards under pressure to a determined distance. The movement controls the volume of materials to be injected.
The screw stops rotating and is pushed forward hydraulically forcing the plastic mold into the mold cavity.

11. INJECTION MOLDING MACHINE
PDT INJECTION MOLD DESIGN
INJECTION MOLDING MACHINE
(a)
(b)
Injection Molding with (a) Plunger and (b) reciprocating screw

12. INJECTION MOLDING MACHINE
PDT INJECTION MOLD DESIGN
INJECTION MOLDING MACHINE
Injection Pressure
Injection Time
Injection Speed
Cooling Time
Mold Temperature
Barrel Temperature

13. PDT 317 - INJECTION MOLD DESIGN
VIDEO : FUNDAMENTAL
INJECTION MOLDING

14. PDT 317 - INJECTION MOLD DESIGN
TYPE OF MOULDS
Cold-runner, two-plate molds
Cold-runner, three plate molds
Hot-runner molds
Multicomponent (Family Mold)
Insert molding
Overmolding
2 - Plates Mold
3-Plates Mold

15. PDT 317 - INJECTION MOLD DESIGN
TYPE OF MOULDS
Advantages of Two-Plate Molds
Low fabrication cost
Simple mold/tooling design
Easy to setting injection molding
machine parameter during molding
Easy to maintenance the mold
Short lead time for mold fabrication
Easy to fitting and assembly the mold
Simple ejection system of mold
2 - Plates Mold
Disadvantages of Two-Plate Molds
Runner and part not automatically separated
(need secondary process to cut)
The gate area can be seen clearly after cut

16. PDT 317 - INJECTION MOLD DESIGN
TYPE OF MOULDS
Advantages of Three-Plate Molds
The runner automatic separated from
the part during mold opening.
The part cycle time can be reduced.
(no need to cut the gate).
Reduce production cost.
Disadvantages of Three-Plate Molds
The mold/tooling structures are
complex.
High cost of tooling fabrication.
High maintenance cost of mold.
Lead time for mold fabrication is long.
3-Plates Mold

17. PDT 317 - INJECTION MOLD DESIGN
Phases of Moulding
Filling
Volumetrically fill the cavity
Pressurization
Build up pressure in the cavity
Packing
Add extra material to reduce shrinkage
Pressurization Phase
Filling Phase
Packing Phase

18. GATING/DELIVERY SYSTEM
PDT INJECTION MOLD DESIGN
GATING/DELIVERY SYSTEM
Sprue
Polymer Entrance Point
Primary Runner
Part Cavity
Gate
Secondary Runner
Cold Slug Well

19. PDT 317 - INJECTION MOLD DESIGN
MOULDING STAGES
Hopper
Barrel
Screw
Mold
Filling
Mold closes
Screw forward
Frozen polymer skin forms at mold walls
Packing Time
Cavity filled
Pressure applied to polymer
Cooling occurs
Gate freezes
Screw is applying a specified pressure to the polymer melt in order to pack more plastic into the cavity.

20. MOULDING STAGES (Cont…)
PDT INJECTION MOLD DESIGN
MOULDING STAGES (Cont…)
Cooling
Part continues to cool until rigid enough to withstand ejection
Screw moves back plasticizing
resin for next shot
Mold Open
Part is ejected

21. PDT 317 - INJECTION MOLD DESIGN
MOULDING CYCLE TIME
Cycle Time:
Fill Time:
Pack Time:
Cooling Time:
Mold Open Time: 22
Sec. 1 9 10 2

22. Defect and Causes in Injection Molding
PDT INJECTION MOLD DESIGN
Defect and Causes in Injection Molding
Defect
Causes
Flashing
Injection Pressure too high
Clamping force to low
Mold fitting not good
Warping
Non-uniform cooling rate
Bubble
To much moisture in material
Shot Mold
Air trap
Injection Pressure not enough
Sink Mark
Injection Pressure too low
Ejector Pin Mark
Cooling time too short
Ejection force too high

23. PDT 317 - INJECTION MOLD DESIGN
Q&A

24. PDT 317 - INJECTION MOLD DESIGN
SEKIAN TERIMA KASIH