The CAE Warpage Analysis of the floor brick product using Polypropylene Wood Plastic Composite Material

• Main Authors: Chen, Shang-Min, 陳尚民
• Other Authors: Lin, Kun-Chang
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/71892080767881613396

碩士 === 遠東科技大學 === 材料科學與工程研究所 === 102 === Wood-plastic composites (WPC) are composite materials made of wood fiber /wood flour and thermoplastics (includes PE, PP, PVC, PS etc.). Chemical additives seem practically "invisible" (except mineral fillers and pigments, if added) in the composite structure. They provide for integration of polymer and wood flour (powder) while facilitating optimal processing conditions. Wood plastic composites can enhance the plastic Young modulus and retain the characteristics of natural wood, so they are widely used in indoors or outdoors building material are often considered a sustainable material. In this study, we use polypropylene (PP) with 35wt% rice hull fiber material to develop the assembly floor brick product. Due to the product has excessive uniform thickness distribution (1.7 ~ 8mm), not meet the uniform thickness principle design of injection products, resulting in severe shrinkage and warpage problem. In general, the industry company uses long cooling time or the after-mold tool to cure this problem, however, the improvement was limited. Also the company used the different material ABS with glass fibers (ABS/GF), PP with rice hull fiber (PP/WF) and PP to compare the warpage effect, the order of the total displacement was PP > PP/WF >ABS/GF. Although there was significant improvement in the warpage deformation using PP with 35wt% rice hull fiber material than PP, but those couldn’t meet customer requirements. Therefore, we used Moldex3D mold flow analysis computer software to discuss the different material selection, mold design, and processing conditions, we hope to find out the better solution to improve the warping deformation of the floor brick product. In this study, we designed three groups of CAE (computer aided engineering) simulation experiment to discuss the warpage deformation of the floor brick product. CAE experiment I：We designed three materials (PP, PP/GF, ABS/GF) and four product designs to discuss their behavior relationship under the full analysis mode (CFPCW) and the fiber orientation effect. CAE experiment II：We discussed the warpage deformation of the major effects, cooling analysis and fiber orientation effect, under the model 1 and PP/GF material. CAE experiment III：We hope to find the optimal process condition, melt temperature, mold temperature, Packing time and the cooling time, under the model 1 and PP/GF material. In this study, we used the total displacement difference to evaluate the warpage deformation. In CAE experiment I, the total displacement difference of the existing mold design (model 1) and PP material is 11.65mm, which is the baseline status. That of PP/GF material is 2.61mm and ABS/GF material is 0.95mm with the improvement ratio of 91.8%. The product design changed from solid cylinder boss (model 1) into hollow boss (model 2) also improved the warpage deformation. In CAE experiment II, the model 1, PP/GF material and uniform mold temperature as a the baseline condition, the total displacement difference increased from 2.83mm to 3.24mm due to uneven cooling effect and the warp direction moved toward the direction of the cavity plate (or stationary part of the mold). These suggested that the existing mold cooling water channels were poorly designed. The total displacement difference decreased from 2.83mm to 1.83mm due to the fiber orientation effect and the warp direction moved toward the direction of the core plate, which was consistent with the deformation of the floor brick product. The CAE results showed that the fiber orientation effect was the key factor to the warpage deformation. In CAE experiment III, the model 1, PP/GF material and existing process condition as a the baseline condition, the optimal process condition was lower melt temperature, higher mold temperature, longer packing time, multi-staged packing pressure setting and longer cooling time. The original total displacement difference of process condition was 2.34mm and that of optimize process condition was 1.81 mm with the improvement ratio of 22.75%.