plastic

1. Injection Molding
MFG 355

2. 1

4. 15 Ton Injection Molding Machine
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5. 77 Ton Injection Molding Machine
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6. Click on frame to start video
150 Ton Injection Molding Machine

7. Equipment
• Injection Unit
Screw drive
arrangement
Feed
hopper
Barrel heaters Nozzle
Tool
Screw Check valve Screw tip

8. Equipment
• Injection Unit

11. Injection
• Parts of the injection screw
– Screw
– Head and check ring

12. Equipment
• Molds

13. Molds

14. Mold Materials
• Aluminum filled epoxy
• Aluminum
• Tool steel
• Stainless steel
• Hotwork die steel
• Beryllium-copper

15. Mold Materials
• Choice based on critical properties
– Machinability
– Coefficient of thermal expansion
– Specific heat capacity
– Thermal conductivity
– Density
– Hardness (abrasion resistance)
– Yield strength
– Weldability

16. Mold Parts
• Bases
– Standard sizes
– Hold mold inserts
– Can decrease overall mold costs

17. Mold Parts
• Guide pins
– Align mold cavities
Guide pins

18. Mold Parts
• Sprue Bushing
– Hot sprue
– Cold sprue

19. Mold Parts
• Sprue Bushing
– Hot sprue

20. Mold Parts
• Sprue Bushing
– Cold sprue
– Sprue puller

21. Mold Parts
• Sprue Bushing
– Cold sprue
– Sprue puller

22. Mold Parts
• Runner

23. Mold Parts
• Runner
– Layout
Conventional Improved Balanced “H” Circular

24. Mold Parts
• Runner
– Layout
Conventional Improved Balanced “H” Circular

25. Mold Parts
• Runner
– Cold well

26. Mold Parts
• Runner

27. Mold Parts
• Gates
Submarine Gate
Pinpoint Gate
Fan or Edge Gate

28. Mold Parts
• Gates
Sprue Gate
Tab Gate
Flash Gate

29. Mold Parts
• Gates
Internal Ring Gate
External Ring Gate

30. Mold Parts
• Gate

31. Mold Parts
• Gate

32. Mold Parts
• Gate

33. Mold Parts
• Cavity
– Where the part is made
– Layout is critical to material flow

34. Mold Parts
• Cavity
– Knit/weld lines
This shows where the
weld lines (shown in red)
will most likely occur with
the part gated in the
center (yellow cone).

35. Mold Parts
• Cooling
– Reduce cycle time
– Control formation of crystalline areas
– Freeze part
Mold cavity
Cooling lines

36. Mold Parts
• Ejector system
Ejector Plate
Ejector pins
Return Springs

37. Equipment
• Clamping Unit

38. Equipment
• Clamping Unit
– Toggle clamping
– Hydraulic clamping
– Hybrid hydraulic-toggle clamping

39. Equipment
• Clamping Unit

40. Equipment
• Clamping Unit
– Toggle system
Click on frame to start video

41. Plant Concepts

42. Safety
• High clamping forces
• High pressure lines
• High voltage
• High temperatures

43. Safety
• Position switches
– Mechanical, hydraulic and electrical
• Shields
• Lock out/tag out

44. Material and Product
Considerations
• Shapes
– Possible to do very complex shapes
• Structural features
– Pins, ribs, bosses, threads, holes
– Deep parts are possible
– Internal or external threads
– Undercuts require sliding mold sections

45. Sliding Mechanism

46. Material and Product
Considerations
• Part design
– Uniform wall thickness
• Helps reduce dimples, shrink marks and distortion
– Ribs
• Save weight at given strength
– No sharp bends
• Helps to fill the mold cavity easier
– Oversize the mold
• Shrinkage amount is dependant on material and
additives/fillers

47. Operations and Control
• Temperature of melt
• Temperature of mold
• Pressure of injection and hold
• Injection or fill rate and time
• Dwell time
• Freeze time
• Ejection (dead time)

48. Special Injection Molding
Processes
• Coinjection molding
– Two separate screws
– Two different material selections
• Color, strength, flexibility

49. Special Injection Molding
Processes
• Coinjection molding
1 2 3

50. Special Injection Molding
Processes
• Coinjection molding
Part 1
Part 2

51. Special Injection Molding
Processes
• Flow-controlled injection processes
– Sometimes called Scorim

52. Special Injection Molding
Processes
• Flow-controlled injection processes
– Sometimes called Scorim

53. Special Injection Molding
Processes
• Gas injection molding
– Employs gas to create hollow parts

54. Special Injection Molding
Processes
• Injection-compression molding
Injection-Compression
Molding
Injection Molding
Parts were
made with the
same mold.
The only
difference
between the
two parts is the
use of the
compression
cycle

55. Modeling and Computer-Aided
Mold-Flow Analysis
• Used to help identify
potential problems
with the mold/part
design
• Models based on the
CAD part
• Adjusted by resin

56. Thank You