5 Ejection Methods For Plastic Mold
Plastic Mould Ejection Injection moulding compounds exhibit a certain amount of shrinkage,i.e., in a cooled condition, the volume is somewhat smaller than in a heated condition. If parts with accurate dimensions are needed, allowances must be made for this shrinkage when establishing the dimensions of the cavities. Shrinkage also causes the molded parts to sit tight on the cores since usually parts are ejected after they have cooled down. As a result, extraordinary measures are required to be able to eject finished parts. These measures include, first of all, careful polishing of all mold surfaces that come in contact with the plastics melt as well as a certain draft in the direction of draw. Since self-acting slight lubrication of the mold surfaces that come in contact with the molded parts is possible only in rare cases,there is a danger that scratches and cracks will occur when the mold is opened or the parts ejected, particularly if the molding compound is very hard. A mirror fini...