Rapid Tooling for Plastic Injection Molding

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Rapid Tooling for Plastic Injection Molding

• Puvas Nandakwang
• Amiteshwar Sidhu

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Outline

• Background
• Project
• Phase I
• Hardware
• Phase II
• Problems
• Solutions
• Future Improvements
• Conclusion

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Background

• Typical prototyping
• cannot provide product characteristics associated
  with the end use material
• difficult and expensive to produce many high
  quality RP parts for testing
• Fabrication of conventional hard tooling
• significant fixed cost
• considerable fabrication time

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Background

• Rapid Prototyping

Indirect OR Secondary Fabrication
Direct Fabrication
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Introduction

• Rapid Tooling
• Soft tooling method
• Rapid Prototyping methods employed to make tools
• Molds such as an injection mold or an RTV mold
  that are made using RP technology
• Low Cost Simplicity!

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Project

• Phase I
• Part Design
• Tool Design (Die)
• Selection of RP process
• Phase II
• Build Part
• Finishing Operations
• Injection Molding

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Phase I Part Design
Back View
Front View
Issues Smooth Edges, Size and Functionality
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Phase I Tool Design
Back View
Front View
Issues Negative of the Part, all Protrusions
on part are Cuts on tool
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Phase I Selection of RP Process

• SLA process was selected because of
• higher strength
• better surface finish
• adequate temperature properties
• Some Numbers
• Glass transition Temperature 149-184F(65-90C)

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Plastic Injection Molding Machine
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Die, after mounted on the shoe
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Ready for injection
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Injecting Plastic
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Phase II Final Products
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Problems

• Wrapping of Die Plates
• - Flatness is lost
• - Locations of holes undergo deviation

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Problems

• Machining Operations
• Face Milling done to restore flatness
• Drilling to align mounting holes
• Design Changes
• Increased die thickness
• Removed mounting holes
• Increased gate length
• Changed shape of gates

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Possible Improvements

• Blue material cracks near the hole
• Design change to facilitate easier access of
  flowing liquid to the section which cracks

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Conclusion

• Rapid Tooling facilitates
• Quick production of tools
• Visualization of problems that might arise in the
  injection molding die design and process
• However deformation during the curing process
  requires to be fixed with machining. Extra volume
  which might be lost due to machining should added
  to the SLA part.