12 injection molding
DESCRIPTION
Very good plastic technology presentationsTRANSCRIPT
Injection Molding
MFG 355
15 Ton Injection Molding Machine
Click on frame to start video
77 Ton Injection Molding Machine
Click on frame to start video
Click on frame to start video
150 Ton Injection Molding Machine
Equipment
• Injection Unit
Screw drive arrangement
Feed hopper
Barrel heaters Nozzle
Tool
Screw Check valve Screw tip
Equipment
• Injection Unit
Injection
• Parts of the injection screw– Screw– Head and check ring
Equipment
• Molds
Molds
Mold Materials
• Aluminum filled epoxy
• Aluminum
• Tool steel
• Stainless steel
• Hotwork die steel
• Beryllium-copper
Mold Materials
• Choice based on critical properties– Machinability– Coefficient of thermal expansion– Specific heat capacity– Thermal conductivity– Density– Hardness (abrasion resistance)– Yield strength– Weldability
Mold Parts
• Bases– Standard sizes– Hold mold inserts– Can decrease overall mold costs
Mold Parts
• Guide pins– Align mold cavities
Guide pins
Mold Parts
• Sprue Bushing– Hot sprue– Cold sprue
Mold Parts
• Sprue Bushing– Hot sprue
Mold Parts
• Sprue Bushing– Cold sprue– Sprue puller
Mold Parts
• Sprue Bushing– Cold sprue– Sprue puller
Mold Parts
• Runner
Mold Parts
• Runner– Layout
Conventional Improved Balanced “H” Circular
Mold Parts
• Runner– Layout
Conventional Improved Balanced “H” Circular
Mold Parts
• Runner– Cold well
Mold Parts
• Runner
Mold Parts
• Gates
Submarine Gate
Pinpoint Gate
Fan or Edge Gate
Mold Parts
• Gates
Sprue Gate
Tab Gate
Flash Gate
Mold Parts
• Gates
Internal Ring GateExternal Ring Gate
Mold Parts
• Gate
Mold Parts
• Gate
Mold Parts
• Gate
Mold Parts
• Cavity– Where the part is made– Layout is critical to material flow
Mold Parts
• Cavity– Knit/weld lines
This shows where the weld lines (shown in red) will most likely occur withthe part gated in the center (yellow cone).
Mold Parts
• Cooling– Reduce cycle time– Control formation of crystalline areas – Freeze part
Mold cavity
Cooling lines
Mold Parts
• Ejector system
Ejector Plate
Ejector pins
Return Springs
Equipment
• Clamping Unit
Equipment
• Clamping Unit– Toggle clamping– Hydraulic clamping– Hybrid hydraulic-toggle clamping
Equipment
• Clamping Unit
Equipment
• Clamping Unit– Toggle system
Click on frame to start video
Plant Concepts
Safety
• High clamping forces
• High pressure lines
• High voltage
• High temperatures
Safety
• Position switches– Mechanical, hydraulic and electrical
• Shields
• Lock out/tag out
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
Sliding Mechanism
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
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)
Special Injection Molding Processes
• Coinjection molding– Two separate screws– Two different material selections
• Color, strength, flexibility
Special Injection Molding Processes
• Coinjection molding
1 2 3
Special Injection Molding Processes
• Coinjection molding
Part 1
Part 2
Special Injection Molding Processes
• Flow-controlled injection processes– Sometimes called Scorim
Special Injection Molding Processes
• Flow-controlled injection processes– Sometimes called Scorim
Special Injection Molding Processes
• Gas injection molding– Employs gas to create hollow parts
Special Injection Molding Processes
• Injection-compression molding
Injection-CompressionMolding
Injection Molding
Parts were made with the same mold. The only difference between the two parts is the use of the compression cycle
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
Thank You