Can someone explain the consequenses of negative volumetric shrinkage ??? how critical is it ? what value is allowed ?
How to solve it when it is near the gate and away from the gate ??
Solved! Go to Solution.
negative volumetric values indicate expansion rather than shrinkage.
Basically, volumetric shrinkage is needed to get the part out of the mold.
The negative volumetric shrinkage indicating material expansion,is due to overpacking of material
and area of part can get stuck in mold, causing part quality issues when open mold and ejecting part.
Avoid negative shrinkage on ribs, as this can cause ejection problems.
Volumetric shrinkage can be controlled by the use of packing profiles.
Packing pressure level by time, and decay as needed, to control the volumetric shrinkage.
Average volumetric shrinkage result :
Hope this helps.