The business of plastic injection molding is mostly scientific and technical, yet there is this element of undefined experience that can only be termed “black art”. Mold polishing seems to fall into this category for many engineers and mold techs.
If the part has blemishes of one sort or another, or is sticking in the cavities, or maybe not filling properly, very often the solution is related to the surface finish.
This is often overlooked, which is unfortunate because it is much less costly than a major engineering change, for example. When the process has been tweaked over and over again, maybe take a second or third look at the mold polish, it could hold the answer.
Learn more about plastic injection molding and mold polishing.