(1) distribution of mold cavity is not scale or insufficient stress caused by uneven parallel local flash, local grievances, should be under the premise that does not affect the product integrity port should be placed in quality center of symmetry.
(2) the force imbalance of movable components and sliding core in the mould will cause flying edges.
(3) when the air under pressure causes the mold parting surface to expand and flanges due to bad exhaust of the mold, a good exhaust system should be set up, or an exhaust groove should be dug on the parting surface.