Page 470 - Injection Molding Advanced Troubleshooting Guide
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470 46 Warp
Keep in mind that when using a fiber-filled material the orientation of the fibers
will result in anisotropic shrink that can in turn lead to warp. The shrink of
fiber-filled plastic in the direction of flow will normally be less than the shrinkage
across flow. Fibers will stay oriented after the mold has been filled and this orien-
tation can in turn lead to warping parts. This orientation impact must be consid-
ered during part and mold design. One factor that can help this anisotropic shrink
is to combine mineral fillers and fiber fillers: the mineral filler will help restrict the
cross flow shrink thereby providing less differential in shrink.
References
[1] Bozzelli, John, “Dont Neglect Cooling...There’s Money To Be Made”, Plastics Technology, April 2010
