Polypropylene (PP) plastic forming properties
(1) crystalline plastics, little hygroscopicity, melt fracture may occur, long-term contact with the hot metal has decomposition
(2) very good liquidity, overflow boundary value around 0.03 mm
(3) the cooling speed, gating system and cooling system cooling should be moderate
(4) large range of molding shrinkage, shrinkage, deformation, shrinkage cavity, depression, strong sex orientation
(5) pay attention to control the molding temperature, low temperature when the orientation is obvious, especially the high pressure of low temperature is more obvious, mold temperature is lower than 50 ℃ plastic lacklustre, easy to produce weld mark and flow mark;More than 90 ℃ when prone to warp, deformation and plastic parts should be uniform wall thickness, avoid gap, sharp corners, to prevent stress concentration