Dynamic template bending

When the mold is injected, the molten plastic in the cavity generates a huge back pressure, generally 600~1000 kg/cm. Moldmakers sometimes do not pay attention to this problem, often change the original design size, or replace the moving template with a low-strength steel plate. In the mold with the top bar topping, the template is bent down during injection due to the large span of the two sides. The moving template must be made of high-quality steel. It must have sufficient thickness. It is not allowed to use low-strength steel plates such as A3. If necessary, support columns or support blocks should be placed under the moving plate to reduce the thickness of the template and improve the carrying capacity.

The ram is bent, broken or leaking.

The quality of the self-made ejector is better, that is, the processing cost is too high, and now the standard parts are generally used, and the quality is poor. If the gap between the ejector pin and the hole is too large, leakage occurs, but if the gap is too small, the ejector pin expands and is stuck due to an increase in mold temperature at the time of injection. More dangerously, sometimes the ejector pin is pulled out at a normal distance and is broken. As a result, the exposed ejector pin cannot be reset and the die is broken during the next clamping. In order to solve this problem, the ejector rod is re-grinded, and a 10-15 mm mating section is retained at the front end of the ejector pin, and the middle portion is ground by 0.2 mm. All the ejector rods must be strictly checked for the fit clearance after assembly, generally within 0.05~0.08 mm, to ensure that the entire ejector mechanism can move forward and backward freely.

Poor cooling or water leakage

The cooling effect of the mold directly affects the quality and production efficiency of the product, such as poor cooling, large shrinkage of the product, or uneven shrinkage and deformation of the warping surface. On the other hand, the mold is overheated in whole or in part, so that the mold cannot be formed normally and the production is stopped. In severe cases, the movable parts such as the ejector are thermally expanded and damaged. The design of the cooling system depends on the shape of the product. Do not omit this system because of the complicated structure of the mold or the difficulty of processing. Especially for large and medium-sized molds, the cooling problem must be fully considered.