[ Jiuzhi Plastics News] Plastic products in the production of injection molding products, due to the uneven cooling and uneven shrinkage of plastic in the cavity and the irrational design of the product structure, it is easy to cause various defects of the product: shrinkage, weld marks , stomata, deformation, napping, top injury, flash. In order to obtain high-quality injection molding products, we must fully consider the structural processability when designing the product. The following methods are combined with the main structural characteristics of the injection molding products to avoid injection molding defects:
The first is the mold opening direction and the parting line. Each injection molding product must first determine its mold opening direction and parting line at the beginning of the design to ensure that the core pulling mechanism is eliminated as much as possible and the influence of the parting line on the appearance is eliminated. After the mold opening direction is determined, the reinforcing ribs, snaps, protrusions and the like of the product are designed to be consistent with the mold opening direction as much as possible to avoid the core pulling to reduce the seam line and prolong the life of the mold. For example, the mold opening direction of the bumper is generally the direction of the body coordinate ,. If the mold opening direction is designed to be inconsistent with the χ axis, the angle must be indicated in the product drawing. After the mold opening direction is determined, an appropriate parting line can be selected to improve the appearance and performance.
Followed by the draft angle, the appropriate draft angle can avoid product pulling. The smooth surface should have a draft angle greater than 0.5 degrees, a fine grain surface greater than 1 degree, and a rough grain surface greater than 1.5 degrees. Appropriate draft angle can avoid product top injury. The design of the deep cavity structure product requires that the slope of the outer surface is smaller than the slope of the inner surface to ensure that the mold core is not biased during injection, to obtain a uniform product wall thickness, and to ensure the material density strength of the opening portion of the product. Again, the product wall thickness, all kinds of plastics have a certain wall thickness range, generally 0.5 ~ 4mm, when the wall thickness exceeds 4mm, it will cause the cooling time is too long, resulting in shrinkage and other issues, should consider changing the product structure. Uneven wall thickness can cause surface shrinkage. Uneven wall thickness can cause pores and weld lines.
Finally, the ribs and the reasonable application of the ribs can increase the rigidity of the product and reduce the deformation. The thickness of the ribs must be less than 1/3 of the wall thickness of the product, otherwise the surface will shrink.
Therefore, as long as we pay attention to the above points in our production process, we believe that we will produce higher quality rubber and plastic products.
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