Common Faults And Solutions in Injection Mold Processing
Apr 20, 2022
The structural form of the injection molding mold and the mold production process will endanger the quality of the plastic product. Sometimes, the injection molding mold will also be abnormal in the production of plastic injection molds, so how do you remove it?
1. The positioning pin is damaged.
The positioning pin is mainly used as a guide in the mold to ensure that the core of the plastic cup injection mold and the forming surface of the concave mold do not collide with each other under all conditions, and the positioning pin cannot be used as a bearing member or an accurate positioning member. Under the following conditions, the fixed mold will cause a large side deflection force when the injection is moving:
(1) When the wall thickness of plastic parts is not uniformly distributed, the speed of material flow through the thin wall is high, which causes a lot of working pressure here;
(2) The sides of the plastic parts are asymmetrical, such as the mold of the trapezoidal clinical diagnosis surface, and the counter-working pressures on the opposite sides are not the same.
2. Moving and fixed mold offset.
For large and medium-sized molds, due to the different charging speeds in each direction, and the danger of the mold's own weight when installing the mold, the moving and fixed molds are offset. Under the above conditions, the lateral deflection force will be added to the positioning pin during injection, and the surface of the positioning pin will be sprayed during ejection, causing damage. In order to deal with the above problems well, a high-toughness accurate positioning key is added on each of the four sides of the clinical diagnosis surface of the mold. It is simple and reasonable to use a cylindrical key. The vertical angle between the positioning pin hole and the parting surface is particularly important. In production, the moving and fixed molds are selected to be clamped at the pointing parts, and then boring on the milling machine at one time, which can ensure the coaxiality of the moving and fixed mold holes, and make the vertical angle deviation Z less. In addition, the heat treatment hardness of the positioning pins and guide posts should meet the design requirements as far as possible.
3. The moving template is bent.
When the mold is injected, the molten plastic in the mold core causes a large back pressure, and the processing of plastic injection molds is generally 600~1000KG/CM2. Mold makers sometimes do not attach great importance to this problem. Usually, G changes the original design specifications, or replaces the moving template with a low-hardness thick steel plate. The template bends down. Therefore, the moving formwork service B uses high-quality stainless steel plates, which must be sufficiently thin and thick. Do not use low-hardness thick steel plates such as A3. When B is required, support point columns or support blocks should be set under the moving formwork to reduce the thickness of the formwork. , increase the bearing capacity.
