Analysis of warpage and shrinkage properties of injection-molded micro gears polymer composites using numerical simulations assisted by the Taguchi method

Microgears containing four cavities and consisting of three different types of thermoplastic materials, namely, the amorphous polycarbonate/acrylonitrile-butadiene-styrene blend (PC/ABS), amorphous polyphenylene-ether/polystyrene (PPE/PS), and crystalline polyoxymethylene (POM) filled with glass fibers were analyzed. Molding parameters such as packing time, cooling temperature, molding and melting temperatures, packing and injection pressures, and fiberglass percentages are the most important factors affecting warpage and shrinkage. Three factors and their interactions were investigated in this case study. The effects of the injection parameters on warpage and shrinkage at different fiberglass percentages and cooling temperatures were analyzed according to the Taguchi method. The minimum values for warpage (0.0051 mm) and shrinkage (2.2886%) were derived from the PC/ABS and PPE/PS composites, respectively. Process efficiency predictions and conformational analyses of the optimal levels for each injection molding parameter were conducted to demonstrate the advantages of the Taguchi analytical method. The highest improvement percentages in the shrinkage and warpage analyses were obtained from the PPE/PS and the PC/ABS, respectively. PPE/PS was the best polymer composite by shrinkage analysis because of its molecular structure and minimum temperature at the flow front range, while the PC/ABS behaved the best in the warpage analysis. (c) 2012 Elsevier Ltd. All rights reserved.