On the relationship between cooling setup and warpage in injection molding

Injection molding process causes differences between designed shape and real parts, all of them associated to shrinkage phenomena. Temperature and pressure distribution during molding process originate local shrinkage, and the internal stresses induces warpage depending on the relative stiffness of each part area. In this paper some measurement results are shown, focused on cooling parameters effect on warpage, using non-contact techniques on several part areas. Results allow visualize warpage changes when melt temperature, cooling time or cooling conditions vary. These measurement results, out of general rules, reveal how final part shape varies with temperature, not only in maximum value but in curvature. (C) 2012 Elsevier Ltd. All rights reserved.