Molds & Tooling
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PARA Warpage Deformation
Problem Phenomenon
PARA products warp with flatness out of tolerance; under high fiber content, anisotropic shrinkage is the main cause, with significant corner effect.
Cause Analysis
PARA usually contains 50~60% glass fiber, with shrinkage about 0.1% in the flow direction and about 0.5% in the perpendicular direction, and anisotropic shrinkage causes warpage; differential shrinkage is secondary; differential cooling with one side of the mold hotter; corner effect with 90° corner closing up to 6°.
Solution
①Change the filling pattern: adjust gate position, add gates, locally change thickness; ②For multi-gate parts test valve gate opening; ③Use overflow diversion; ④Mold temperature >125~130°C to ensure complete crystallization and reduce differential cooling influence.
Key Takeaway
The core of PARA warpage treatment is fiber orientation management; changing the filling pattern is more effective than process parameters; after complete crystallization at mold temperature above 125°C, differential cooling influence is very small.
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