Generally, modified polypropylene (P P) is selected as the material, which is composed of PP (about 60%), rubber (about 30%), filler (talc) about 9%, and additive (antioxidant, preservative, nucleating agent, anti ultraviolet agent, etc.) 1%. The material is resistant to low temperature impact (- 30 ℃, Izod impact strength is 6.0kg.cm/cm), with high fluidity and good sealing performance of coating (corresponding to E-10).
In addition, the material has good appearance quality and can meet the requirements of fine fusion grain, good surface tension and A-class surface without fusion grain. The material is recyclable, 100% recyclable.
In the product design stage, use Moldflow software to carry out CAE analysis of the design and technical production verification. The analysis contents include: glue point position, glue point size, product weight, mold locking force, product filling simulation, flow field temperature, filling pressure, shear stress, shrinkage, gas retention position, weld, warpage, coolant temperature and maximum temperature of parts. Through CAE analysis, we can adjust and prevent the bad situation of the product in the design stage, so as to ensure the smooth formation of the product.
It is worth mentioning that the bumper is not designed as "equal meat thickness", but "meat thickness change" according to different parts of the product, with the change range of 2.6-3.4mm. The general principle is: the middle part belongs to the thick meat area, the distal end of the glue mouth is the thin meat area, and the confluence of the products is the thin meat area.
Through the meat thickness gradient technology of the product, the following functions can be realized: less injection ports, generally 2-4 nozzles, so the mold is simple and the cost is relatively low; rapid prototyping can be realized, because the far end of the rubber nozzle is a lean meat area, which is easy to realize the filling of the product; By calculating the difference between the weight of equal thickness bumper and that of equal thickness bumper by about 15%, the injection material can be saved.