5. The jack is bent, broken or missing
The quality of the self-made ejector is good, which means that the processing cost is too high. Nowadays, standard parts are usually used, and the quality is average. If the gap between the ejector pin and the hole is too large, material leakage will occur, but if the clearance is too small, the ejector pin will swell due to the rise of the mold temperature during injection. What is more dangerous is that sometimes the ejector pin is ejected at a normal distance and breaks. As a result, the exposed ejector pin cannot be reset when the next mold is closed, and the concave mold is damaged.
In order to solve this problem, the ejector rod was reground, and a fitting section of 10-15 mm was retained at the front end of the ejector rod, and the middle part was milled 0.2 mm smaller. After the assembly of all ejectors, the fit clearance must be strictly checked, generally within 0.05 ~ 0.08 mm, to ensure that the entire ejection mechanism can move forward and backward freely.
6. Poor cooling or water leakage
The cooling effect of the mold directly affects the quality and production efficiency of the product, such as defects such as poor cooling, large shrinkage of the product, or uneven shrinkage and deformation of the warped surface. On the other hand, the mold is overheated in whole or in part, making the mold unable to be molded normally and stopping production. In severe cases, the movable parts such as the ejector pin are thermally expanded and stuck and damaged.
The design and processing of the cooling system are determined by the shape of the product. Do not omit this system because of the complex mold structure or difficult processing, especially the large and medium molds must fully consider the cooling problem.
7.Guide groove length is too small
Some molds are limited by the area of ​​the template and the length of the guide groove is too small. The slider is exposed outside the guide groove after the core pulling operation is completed. This makes it easy to cause the slider to tilt during the core pulling phase and the initial stage of mold clamping reset, especially in the mold clamping When the slider is not reset smoothly, the slider is damaged or even damaged by bending. According to experience, after the slider completes the core pulling action, the length remaining in the slide groove should not be less than 2/3 of the total length of the guide groove.