4. The movable template is bent.
When the injection mold is injected, the molten plastic in the cavity produces a huge back pressure, generally 600 ~ 1000 kg/cm2. Mold makers sometimes do not pay attention to this problem, and often change the original design size, or replace the movable template with low-strength steel plate. In the mold with ejector pin, the large span between the two sides of the seat causes the template to bend during injection. Therefore, the movable formwork must be made of high-quality steel, with sufficient thickness, and low-strength steel plates such as A3 should not be used. When necessary, support columns or support blocks should be set under the movable formwork to reduce the thickness of the formwork and increase the load-bearing capacity.
5. The ejector rod is bent, broken or leaking.
The self-made ejector rods are of better quality, but the processing cost is too high. Nowadays, standard parts are generally used, and the quality is poor. If the gap between the ejector pin and the hole is too large, leakage will occur, but if the gap is too small, the ejector pin will become stuck due to the increase in mold temperature during injection. What's more dangerous is that sometimes the ejector rod will not move and break when it is ejected for a normal distance. As a result, the ejector rod exposed during the next mold clamping cannot be reset and the die will be damaged. In order to solve this problem, the ejector pin was re-ground, leaving a 10-15 mm mating section at the front end of the ejector pin, and the middle part was ground down by 0.2 mm. After all ejector rods are assembled, the fitting clearance must be strictly checked, generally within 0.05~0.08 mm, to ensure that the entire ejector 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 poor cooling, large shrinkage of the product, or uneven shrinkage, resulting in defects such as warping deformation. On the other hand, the whole or part of the mold is overheated, so that the mold cannot be formed normally and the production is stopped. In severe cases, the movable parts such as the ejector rod may be thermally expanded and jammed and damaged. The design and processing of the cooling system depends on the shape of the product. Don't omit this system because of the complex structure of the mold or the difficulty in processing. Especially for large and medium-sized molds, the cooling problem must be fully considered.