1. INJECTION MOLDING & TECHNIQUE

2. OBJECTIVES
VARIOUS MOLDING TECHNIQUES FOR DIFFERENT TYPES OF COMPONENTS
ABOUT INJECTION MOLDING MACHINE.
ABOUT MOLD
FEEDING SYSTEM
MOLD FLOW ANALYSIS
UNDERCUT AND REMOVAL PROCIDURE
PLASTIC PRODUCT DESIGN
COMMON DEFECTS IN PLASTICS PARTS

3. INJECTION MOLDING : I/P & CHILD PARTS,BUMPERS, PILLAR TRIMS.
VARIOUS MOLDING TECHNIQUES FOR DIFFERENT TYPES OF COMPONENTS.
INJECTION MOLDING : I/P & CHILD PARTS,BUMPERS, PILLAR TRIMS.
EXTRUSION : SEALING SYSTEMS OF AUTOMOBILE, PIPE (PLASTIC & RUBBER)
BOLW MOLDING : DUCTS , BOTTLES, TOYS.
THERMO/ VACUUM FORMING : DISPOSABLE CUP & TRAY,
EXPANDED FOAM MOLDING : STEERING WHEEL,
ROTATIONAL MOLDING : WATER TANK,SPEARS.

4. ABOUT INJECTION MOLDING MACHINE.

5. MAJOR PARTS OF MOLDING MACHINE
Injection Unit
Clamping& Ejection Unit

6. DETAIL PARTS OF INJECTION MOLDING MACHINE & THEIR FUNCTION

7. ABOUT MOULD.

8. TYPES OF MOLD BASED ON FEEDING SYSTEM COLD RUNNER MOLD HOT SPRUE MOLD
HOT RUNNER MOLD
BASED ON NUMBER OF PARTS
SINGLE CAVITY MOLD
MULTY CAVITY MOLD
BASED MOLD OPENING
2 PLATE MOLD
3 PLATE MOLD
BASED ON TYPE OF COMPONENT
SINGEL PART MOLD
FAMILY MOLD
BASED ON SPECALITY
COINJECTION MOLD
INSERT MOLD

9. BASED ON MOLD OPENING 2 PLATE MOLD 3 PLATE MOLD SINGLE OPENING
ADVANTAGE
1)MOLD WILL BE SIMPLE & CHEAP
2) VARIOUS TYPE OF GATES CAN BE ADOPTED.
SINGLE OPENING
DISADVANTAGE
1)MOLD WIDTH AND LENGTH WILL BE MORE THAN 3 PLATE MOLD
2) AUTO DEGATING WILL BE POSSIBLE ONLY IN SUBMARRINE GATE
FIRST OPENING
SECOND OPENING
3 PLATE MOLD
ADVANTAGE
1) MOLD SIZE WILL BE LESSER AS THE FEEDING SYSTEM WILL BE ON UPPER PLATE
2) AUTO DEGATING POSSIBLE
DISADVANTAGE
1) MORE COSTLY
2) SLOWER PRODUCTION RATE
3) MOLD HEIGHT WILL BE MORE

10. BASED ON FEEDING SYSTEM
HOT SPRUE MOLD
Hot Runner Benefits
Faster Cycles
% Faster
Eliminates Material Waste
- No Sprue or Runners(IN HOT RUNNER SYSTEM)
Improves Part Quality
- Less Stress
- Better Appearance
HOT RUNNER MOLD

11. MOLD PARTS SPRUE BUSH TOP PLATE GUIDE BUSH` GUIDE PIN CAVITY PLATE
SLIDER ASSLY
COMPONENT
CORE PLATE
CORE BACK PLATE
RETURN PIN
GUIDE BUSH
EJECTOR GUIDE PIN
SPACER BLOCK
BOTTOM PLATE

12. FEEDING SYSTEM

13. SPRUE
-It is the connecting path between machine nozzle & runner system.
RUNNER
-It is the connecting path between sprue & gate.
GATE
-It is the connecting path between runner and component.

14. SPRUE
Sprue is the beginning of the melt delivery system within the mold
The interface between the nozzle & the mold
Taper shape has been made for avoiding the back flow of material.

15. SPRUE PULLER
REVERSE
TAPER
BEST
Z PULLER
GOOD
GROOVE
TROUBLE-
SOME

16. RUNNER SYSTEM A runner system that has been designed correctly will:
Achieve the optimal number of cavities
Deliver melt to the cavities
Balance filling of multiple cavities
Balance filling of multi-gate cavities
Minimize scrap
Eject easily
Maximize efficiency in energy consumption
Control the filling/packing/cycle time.

17. A A RUNNER BALANCING B -FOR UNIFORM FILLING OF COMPONENT
-FOR MAINTAINING UNIFORM PRESSURE INSIDE MOLD
-REDUCE FILLING TIME A B
UNBALANCED RUNNER SYSTEM A
BALANCED RUNNER SYSTEM
(CHANGING RUNNER LAYOUT)
BALANCED RUNNER SYSTEM
(CHANGING RUNNER DIA)

18. COLD SLUG WELL Flow Direction Cold SlugWell
-Plastic looses its temp during flow through runner.
-Cold slug well is provided to accommodate the initial cold material and release behind hot material into cavity.
Cold SlugWell

19. Auto-Ejection Trimmed
GATING
Manually Trimmed
Auto-Ejection Trimmed
Direct (sprue) gate
Tab gate
Edge (standard) gate
Disc/Diaphragm gate
Spoke gate
Fan gate
Film(Flash) gate
Ring gate
Pin gate
Submarine (tunnel, chisel) gate
Hot-runner (hot-probe) gate
Valve gate
* The shape of gate will be decided based no the shape & appearance requirement of component.

20. DIRECT SPRUE GATE Sprue Molded Part
Suitable for single cavity large components.
Molded Part
Sprue

21. Single Tab Gate Multiple Tab Gate 6 in. Max 12 in. Max Tab Tab Gate
TAB/OVERLAP GATE
Suitable for stress free and high optical clarity components.
Single Tab Gate
Multiple Tab Gate
6 in. Max
12 in. Max
Tab
Tab
Gate
Gate
Sprue
Sprue
Gate
Tab

22. EDGE GATE
Most commonly used.
Land Length
0.030
Inches Maximum

23. DISC/DIAPHARGM GATE
Runner
Runner
Sprue
Part

24. FAN GATE Suitable for larger area with thin wall components. RUNNER
PART
GATE
LAND

25. FILM /FLASH GATE Parallel Runner Parallel Runner Runner Gate
Suitable for thin walled flat comopnents.
Used for the components required with stress and warpage free.
Used for transparent components where flow mark is not allowed.
Parallel Runner
Gate
Parallel Runner
Runner

26. RING GATE
Gate
Runner Disk
Gate
Part

27. PIN POINT GATE
0.050
0.020 Land Length
900

28. SUBMARRINE GATE Molded Part Sprue Parting Line Zero Land Length
Grind Flat on Gate Side, Min. 20
Tunnel
Gate
Knock Out Pin
Fasten Pin Head To Prevent Turning

29. SUBMARRINE GATE R R
Gate

30. MOLD FLOW ANALYSIS

31. UNDERCUT AND REMOVAL PROCIDURE

32. UNDERCUTS ARE THE SHAPES
-WHOSE ORIENTATION ARE NOT ALLONG WITH MODLING DIRECTION OF THE ENTIRE PART
-LOCATION OF THESE SHPAES WILL BE BELOW PARTING LINE.
TYPES OF UNDERCUT
INTERNAL UNDERCUT
EXTERNAL UNDERCUT

33. INTERNAL THREAD SNAP LID TYPES OF UNDERCUT INTERNAL UNDERCUT
It can be removed by
Force ejection
Use of collapsible core
Use of lifters
Use of unscrewing mechanism(for threads)
INTERNAL THREAD
SNAP LID

34. External Thread Detail on Side TYPES OF UNDERCUT EXTERNAL UNDERCUT
It can be removed by
Side core actuated by
mechanical pins,
Hydrolic &Phumatic cylinders
External Thread
Detail on Side

35. TECHNIQUES FOR UNDERCUT REMOVAL
CORE CAVITY MATCHING AREA FOR HOLE
CORE CAVITY MATCHING

36. SLIDER MECHANISM COMPONENT SLIDER CAVITY CORE HEEL BLOCK CAM
STOPPER PIN

37. SIDE CORE MOVEMENT BY HYDRAULIC CYLINDER
Cavity
Core
Pin
Hydraulic Cylinder
Plastic
MOLDING DIRECTION
Cored Hole
Core

38. LIFTER MECHANISM

39. PLASTIC PRODUCT DESIGN

40. BASIC DESIGN CONSIDERATIONS
The first requirement is to have a properly modeled part that is fully moldable
Sufficiently drafted faces to easily eject the part.
No undercuts (will require lifters or sliders)
Wall thickness should be uniform(if changing then it has to be gradually for avoiding shrink mark)
When creating internal ribs, they should be no greater than 1/3t of the part’s wall thickness to avoid sink marks on the outside of the part.
Drafted faces
No draft = difficult to eject

42. COMMON DEFECTS IN PLASTICS PARTS

43. Short Shot
Flash
Weld Lines
Ejector Pin Marks
Sink Marks

44. Short Shot
Cold material, cold mold, insufficient pressure, non uniform mold temperature, insufficient feed, entrapped air, insufficient external lubrication, insufficient plunger forward time, small gates.
Short defect

45. Flash
Material too hot, Inj Pressure too high, High packing pressure, Less clamping force, Poor parting lines or mating surfaces
Part w/ Moderate-Heavy Flash
Flash

46. Weld Lines
Weld lines is the meeting face of 2 flows coming in opposite direction. Part is weak at Weld line.
Can result from poor gate placement
Unavoidable areas
Gate
Weld Line
Weld
Line
Weld lines occurs if material temperature is low, mold temperature will be improper, improper gate position, improper runner balancing.

47. Ejector Pin Marks
Marks are often left on the part in the area where the ejector pins
pushed. Four possible cause:
1) Pin above
flush
2) Pin below
flush
3) Clearance
around pin
4) Improper cooling time
5) Ejection force more.
6) Part sticking.

48. Sink Marks Sink mark occurs due to abrupt change of thickness.
Thickness to be considered for every shape(Rib, Boss, Clip mountings)
Minor sink marks can be removed by texturing
Thick sections cause
sink marks
Bad
Design
Improved
Design

49. Sink mark removed by optimizing the rib thickness to 1/3 t.
Result after redesigning the Internal Ribs to be 1/3t or less of the nominal wall thickness
Sink due to ribs

50. THANK YOU