Everything you always wanted to know about screws

摘要

In an earlier column,I promised to talk about the heart of an injection molding machine,the screw.What's so important that the lowly screw warrants a whole column? Like most aspects of plastics processing,it's about money.But first,some screw basics.The screw rotates inside the injection molding machine's barrel and performs three basic functions.The first function is to introduce resin pellets into the barrel.The second is to"compress"and shear the pellets in the heated section of the barrel,which melts and homogenizes the resin.The third involves metering the melt into proper quantities so the resin can be shot into the mold.Simple,right?