Simulating Geometrical Variation in Injection Molding
In every manufacturing process there are variations from nominal values that cause part- and assembly variation which can lead to deficient products. Knowledge of this variation and the ability to simulate them are important in developing design concepts. Plastics are predicted to have increased importance in the manufacturing industry. However, there is a lack of understanding of the variation in the produced plastic parts and how designers should take these variations under consideration. Existing software for simulating plastic parts produced in the injection molding process is not useful for variation simulation because of long running times. In this paper a procedure to simulate part variation using a regression model is presented. This regression model is build and fitted using design of computer experiments. Further, the contributions of process parameters on plastic part variation are analyzed. A case study conducted on a cell phone shell resulted in a regression model that was able to give close agreement with the injection molding simulation and thus enabling variation simulation. The process parameters contributing the most to geometrical variation were melt temperature and packing time.