There are holes or opening in plastic workpieces which used for a variety of purpose, such as assembly with other parts, decorate the workpiece or give it more eye appeal, or as ventilators and so om. Holes or openings can be defind as round, squre, rectangular, eliptical, etc, they may be classified as blind holes, through holes, step holes, recess step holes, and intersecting holes (FIG 2.18).
Design of holes or opening of workpieces affect the construction of mould which leads to change the cycle time if holes or openings are deisgn incorrectly, the following machining may need for workpiece, and that also may cause the overall cycle to slow down and the high cost of mold manufactory. Holes can also affect workpiece integrity and strength due to the formation of knit lines or weld lines.
