Plastic injection molding

Plastic injection molding

Injection molding is a manufacturing process, which is making semi-finished parts of certain shapes by pressurizing, injecting cooling and separating molten thermoplastic.

Validate and optimize your tool design

Agenda

  • Challenges
  • Design phases
  • Simulation methods
  • Summary and question

Challenges

Many factors and decisions for molded components

  • Continual change

Part geometry, process type, material design, mold design

  • Application criteria

Function, cosmetics, volume, economics, life cycle

  • Variations

Lot-2-material, machine ware, machine cloning, mold ware

Process and analysis types

  • Gate location analysis
  • Molding window
  • Filling
  • Runner balancing
  • Fiber orientation
  • Packing
  • Design of experiment
  • Venting analysis
  • Crystallization analysis
  • Core shift analysis
  • In-mold label
  • Wire sweep paddle shift
  • Cooling and heating analysis…………steady state, transient, multi cycle, conformal
  • ‘repaid heating and cooling…………water, steam electrical or induction
  • War page and shrinkage analysis
  • Thermoplastic injection molding
  • Two-shot molding sequential, insert molding, over-molding, IMD
  • Gas-assisted injection molding
  • Injection compression molding
  • Bi-injection molding
  • Microcellular injection molding
  • Birefringence
  • Structural reaction injection molding
  • Rubber, liquid silicone injection molding
  • Multiple-barrel reactive molding
  • Reaction injection molding
  • Microchip encapsulation and underfill encapsulation
  • Export as-manufactured properties to FEA
  • Defect visualization

The Best opportunity for the design process

  • Part design

Concept, select material, prototype, estimate cost…..

  • Mold design

Quoting, concept, initial layout, during fabrication…….

  • Process development

Develop a stable process, optimize quality criteria, and minimize cycle time

  • Production troubleshooting

Oops…….. I did it again

Product development cycle

  • Lower costs through upfront insight into the part and mold optimization
  • Reduce time to market and avoid warranty issues and recalls
  • Have confidence that the design is the right

Part design

DFM

Normal wall thickness

  • Thickness variation
  • Traffic-light display
  • Plastic design rule: thickness changes no more than 30% of nom. Wall thickness

Draft angle

  • Draft variations
  • The Draft is acceptable locations

Undercut

  • Suitable undercuts

Molding window analysis

  • Take the guesswork out of your process window

Helps determine process window and optimum conditions

  • Full range of  plastic mold, melt temperature
  • Pressure limit
  • Temperature drop through part

Define the size of window by

  • Number and location of gates
  • Per geometry
  • Material – can compare several materials

Mold design

  • Runner system
  • Venting
  • Steel types
  • Cooling and heating

Cooling and heating

Revised design

  • Range 72 – 105 degree
  • Difference 33 degree
  • Average tem 89.1 degree

Original design

  • Range 55 – 119 degree
  • Difference 64 degree
  • Average tem 88.2 degree

Variable coolant inlet temperature and coolant during a cycle:

  • Heating phase
  • Air purge
  • Cooling phase
  • Air purge

Mold heated by:

  • Water, steam, electrical or induction

Heating and cooling phase:

  • Time or temperature (thermocouple) controlled

Summary

The design is the choice of your

  • Mold design
  • Part geometry
  • Process type
  • Material

Validate and optimize your design

  • Part simulation
  • Runner simulation
  • Venting simulation
  • Cooling and heating simulation
  • Design of experiment