Learn From These Shrinkage Guidelines Before You begin injection molding design.
shrinkage [caption id="attachment_739" align="aligncenter" width="736"] shrinkage[/caption] The fact must be recognized that each plastic material has specific characteristics which are inherent. Shrinkage , or the contraction that takes place in a molded piece after it has been formed in the mold, comes in this category. While the problems of shrinkage are of more significant concern to the designer of molds than to the designer of molded articles, both should understand the fundamentals of shrinkage. Shrinkage is defined as the difference between corresponding linear dimensions of the mold and of the molded piece, both measurements being made at room temperature. This shrinkage in phenolics generally ranges from 0.001 to 0.015 in. Per in., depending upon the type of t hermosetting plastic , the material from which the mold is produced, and the conditions under which the piece is molded. Of thermoplastic materials, polyethylene will shrink as much as 0.0...