Mould: Undercuts Design (4)

The biggest problem of using removing the workpiece from the mold is to avoid the distortion of workpiece. Sometimes the depth short and the plastic material is in high flexibility or flexural modulus, the workpiece can bend enough to eject the workpiece from the mold without damaging the workpiece, and the workpiece must also have enough room to flex and deform, the workpiece can be ejected from mold directly Fig. 2. 32 shows that workpieces in thermoplastic materials with thread or undercuts can be stripped from a mold. Fig. 2.32a shows the workpiece with internal undercuts or thread, and Fig. 2. 32b is the workpiece with external undercuts.

Most flexible thermoplastic materials can tolerate a 10% strain in the mold ejection and not encounter permanent deformation. Usually, if the molded holes not parallel to the draw, the more complicated molds or more direct molding labor will be needed than do holes parallel to the draw, and thus, higher mold costs result. Therefore, holes entering the side of the workpiece, especially not parallel to the draw, should be avoided if possible.