Applied Methodology Design for Manufacturing (Injection Molding) Daniel Codd, Jason Liang, Dan...
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Transcript of Applied Methodology Design for Manufacturing (Injection Molding) Daniel Codd, Jason Liang, Dan...
Applied MethodologyDesign for Manufacturing
(Injection Molding)
Daniel Codd, Jason Liang,
Dan Tulayasathien, & Keith Ip
Background
• Project objective:– Reduce assembly time and cost.
• Design concept:– Replace existing honeycomb side-panels with
injection molded plastic panels.
Design Rationale
Why injection molding?– Reduce part count.– Less labor intensive.– Reduce assembly time.– Increase yield rate of the final product.– Reduce manufacturing cost.– “Unlimited” quantities.– Little or no finishing process.
Introduction to Injection Molding
Plastic hopperPlastic hopper
Die and pressDie and press
Injection ScrewInjection Screw
Common Problems withInjection Molding Process
• Part shrinkage
• Insufficient venting causing air bubbles
• Sink marks due to unequal thickness
• Poor surface finish
• Distortion from insufficient cooling
DFM: Injection Molding
Sharp corners restrict plastic flow.
DFM: Injection Molding
Radiused corners also add to the stiffness of the design.
DFM: Injection Molding
Webs around bosses reduce weightand prevent sinkage marks and voids.
Bad Good
DFM: Injection Molding
Keep in mind flow direction whenmaking changes in wall thickness
DFM: Injection Molding
Uniform wall thicknesses will minimize shrinkage and reduce void formation and sinkage.
Strategies to IncreaseStrength and Stiffness
• Ribs: rule of thumb for proportions.
• Rib thickness should be 2/3 of wall thickness.
Strategies to IncreaseStrength and Stiffness
• Ribs: rule of thumb for preventing sink marks.
Strategies to IncreaseStrength and Stiffness
• Ribs: Circular or diagonal ribbing reduces twisting; bidirectional ribbing reduces sagging and bending.
Strategies to IncreaseStrength and Stiffness
• Lip
The rounded lip (C) not only draws the eye away frommisalignment, but also acts as a decorative element andfunctions as a handle for taking the pieces apart.
Strategies to IncreaseStrength and Stiffness
• Webs around bosses
Strategies to IncreaseStrength and Stiffness
• Gussets
Strategies to IncreaseStrength and Stiffness
• Part contour and Metal reinforcement
Knowledge Captured
• Ribs = less weight, more stiffness.• Rib thickness = 2/3 wall thickness• Oriented to provide maximum bending stiffness.
(waffle pattern)
• Contoured shape helps increase stiffness.
• Use of lips and gussets stiffens the panel.
• Use of webs around bosses prevents sink marks.
Applied Methodology to Design
RibsRibsLipsLips
WebsWebs
Any Questions?