Long Glass Fiber Reinforced Reaction Injection Molding Quality Research

Long fiber reinforced reaction injection molding (LFI), as a process for producing polyurethane (PU) products, has just been applied in our country in few years, and many technology issues have not been resolved. Combined with the Compact 16/40 with LFI Unit introduced by a well-known automotive interior company recently, quality problems of the PU products on LFI were solved.1) By analyzing LFI process and the characteristics of PU forming, the main process parameters impacting on the quality of products and process of forming were determined.2) The reasons for defective products in process were analyzed, and solution of deficiencies were provided, so that advices for improvement of the quality of products were given.3) By simulating and analyzing the liquid injection process with MoldFlow-flow analysis software, the truth of defects appearance was discovered. To avoid air bubbles on the products' surface, optimization of process parameters was done. The best pouring length, material temperature and shutting time were obtained. Through changing pouring track, the number of air pockets were reduced and their location were logical. The principles to set pouring track were given afterwards.4) By simulating PU curdling and cooling course with MATLAB, the laws of temperature and reaction extent were known. The analysis on impact of technical parameters shows that, the mold temperature is the key parameter impacting on PU forming. When the temperature of molds is high enough, the products will have excellent surface quality and stripping time will be reduced.