Plastic Injection Molding Of Roundness

​（1） Generally, effect to the roundness by the gate type tend to be better in the following order.
​           Side gate ＜ Pin gate（double points） ＜ Pin gate （triple points） ＜ Center sprue gate
（2） Weld might influence the roundness, especially in GF reinforced grade, so take care of the gate location, try to mold under a good liquidity condition, and be careful of the mold gas vent.
（3） Deformation towards surface run out direction is often occurred by the shrinkage ratio difference between diametrical direction and circumferential direction. Other than taking balance in shape, there is a method that place a rib towards circumferential direction to strengthen the stiffness and remedy. The multi-point pin gate is relatively effective against the surface run out.