Mold-gate blush

Gate blush (gate splay) n. A blemish or disturbance in the gate area of an injection-molded article. It occurs when the melt fractures as it emerges from the gate due to sudden release of large elastic stresses. 

Injection molding Uniform melt flow, enhanced physical properties Reduce gate blush Reduced jetting Can reduce flow lengths if too high... 

Injection molding machines Resin should be dried < 0.02 %. Do not use resin that has been out of the dryer for > 20 min. Cold molds are difficult to fill and require higher injection pressures. Hot molds, generally, give better finish and less molded-in stress. Melt temperature is very sensitive to very small changes in rpm or back pressure despite sensor or controller set point. Measure with hand held pyrometer or laser sensor. Need slower fill rate for spme-gated parts to prevent blush, splash or jetting. If the walls are > 5 mm, then slow fill helps reduce sinks and voids. 

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