Shrinkage and Warpage Mechanism of Overflow Water-Assisted Injection Molding Short Fiber-Reinforced Polymers

Experimental study on the shrinkage of short fiber-reinforced polymer injection molding products during the overflow water-assisted injection molding (OWAIM) process, and and analysis of the influence of process parameters with the computer-aided engineering (CAE) were performed. The investigation shows that the shrinkage of the product increases linearly along the melt flow with the increase of water injection pressure. The shrinkage of products is on the rise with the increase of water injection pressure, melt temperature, and mold temperature, but it is decreasing with the increase of flow delay time and fiber mass content. Based on the Taguchi orthogonal array design, an experiment study was conducted to characterize the effect of processing parameters on the shrinkage of OWAIM pipe. The results show that decreasing the mold temperature and increasing the fiber mass content can effectively reduce the shrinkage and warpage of products, thus improving the product quality.