Dozing, Shot Size And Cushion Flashcards
(18 cards)
What effect does reducing injection pressure have on part weight?
Decreases the amount of material packed into the mold, reducing weight.
Less material fills the cavity, which may lead to short shots if decreased too much.
How does lowering packing pressure affect part weight?
Limits extra material flow during cooling, lowering weight.
Reducing packing pressure can help avoid over-packing.
What is the impact of shortening holding time in the injection molding process?
Reduces material density and shrinkage compensation.
Shortening holding time minimizes excess material in the part.
What is the effect of decreasing injection speed?
Reduces over-packing and lowers part mass.
Slower filling allows better control over material flow.
How does slightly increasing melt temperature assist in weight reduction?
Improves flow, allowing lower packing pressure without causing defects.
Higher temperatures should be kept within the material’s recommended range.
What happens when cooling time is reduced?
Less time for the material to shrink and densify, resulting in lighter parts.
Ensure the part is fully solidified to avoid warpage.
How does adjusting shot size impact part weight?
Directly reduces material consumption and part weight.
Smaller shot sizes lead to lighter parts.
What is the role of a venting system in the injection molding process?
Allows air to escape easily, reducing over-packing and ensuring consistent part weight.
Fill in the blank: Packing pressure should be reduced incrementally by _______ to prevent short shots.
5-10%
True or False: Cushion is included in the shot size.
True
What is the relationship between shot size and cushion?
Shot Size = Total plastic injected + Cushion.
The cushion ensures consistent packing pressure.
What does the dosing position determine in the injection molding process?
How much plastic the screw pulls back and melts.
Cushion is not included in this measure.
How should injection pressure be optimized while maintaining cushion?
Reduce pressure slightly while keeping enough force to push material into the mold.
Monitor cushion value and adjust within a 5-15% range.
What are the expected effects of reducing cooling time slightly?
Allows slight shrinkage, reducing part density while ensuring the part is fully solidified.
Monitoring part warpage and surface quality is crucial.
What is the expected effect of increasing melt temperature by 5-10°C?
Easier flow, reduces weight while maintaining cushion stability.
What is the significance of fine-tuning shot size?
Helps maintain the cushion while reducing the overall part weight.
What parameter should be adjusted to avoid over-packing while maintaining flow?
Injection speed should be decreased slightly.
What is the expected effect of adjusting packing pressure?
Less material enters the mold after initial filling, reducing part weight.
It’s important to ensure enough material to maintain cushion.
