Influence of Molding Conditions on the Shrinkage and Warpage Behavior of Standardized Test Specimens

Standardized test specimens were produced under different molding conditions using a low-cost polypropylene material filled with calcium carbonate that is used in large quantities in automotive industry. In order to experimentally investigate the influence of molding conditions on the test specimen shrinkage and warpage behavior six process parameters such as melt temperature, packing time, cooling time, injection speed, packing and injection pressures, were closely considered by maintaining the mold temperature at 30 degrees C. For accurate measurement of shrinkage and warpage we scanned each test specimen with an optical 3D scanner. Optimal set of process parameters, which gives minimal shrinkage and warpage, was determined by Taguchi method. The most influential parameter was statistically obtained through analysis of variance method. The obtained results showed that among the selected six process parameters the packing pressure had the highest influence on the shrinkage and consequently warpage of standardized test specimens.