Xinxiang Bolite Rubber Products Co., Ltd. Address: Daqu Town Industrial Park, Fengquan District, Xinxiang City Phone: 0373-5788884 Contact: Manager Han Mobile phone number: 13007663261 Mobile phone number: 13569839119 QQ: 1171150508 Fax: 0373-5788884 Email: email@example.com
What should I do if the product is scratched during injection molding?
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We all know that the injection molding machine has a microcomputer control to achieve a fully automatic or semi-automatic operation mode. There are often many situations when the injection molding machine is working, the most of which is the different scratches on the surface of the product, which is a headache and has reduced work efficiency, so if I should adjust to this situation, today we will talk about Some time.
First, the cause of the dent
1.The thickness of each part of the product is different
2.Insufficient internal pressure of the mold
3.Insufficient mold cooling
4.Deformation due to insufficient cooling time
1. In the process of producing products, dents are the most frequent of the bad phenomena. The plastic injected into the mold shrinks during cooling. The part that is cooled early is the surface that hardens first, and air bubbles will be generated inside. The so-called dents are cooling. The slow part creates a pronounced concave surface in the direction of the bubble contraction.
2. Materials with large shrinkage are also prone to dents. When changing the molding conditions to eliminate dents, the setting conditions should be set in the direction of small shrinkage. That is, the mold temperature and the barrel temperature decrease, and the injection pressure increases, but it should be noted that this may cause residual internal stress.
3. It is better not to notice the dents, so if it does not affect the appearance, it is intentionally processed into a corroded pattern on the mold, such as grain, grain, etc. In addition, if the molding material is HIPS, it is effective to lower the mold temperature to reduce the finish. However, once these methods have dents, it is difficult to repair polished products.
Third, the solution
1. Immediately: Increase injection pressure, extend injection holding time, reduce barrel temperature and mold temperature, and force cooling where dents occur.
2. Short-term: make up for the edge where dents occur. When there is a small space in the material passing side where the dent is generated, the side is thickened.
3. Long-term: Differences in thickness of the design product should be completely avoided. The ribs that are prone to dents should be as short as possible.
Differences in materials
Molding materials with large shrinkage also have large dents. For example, PE, PP, even if only a small amount of reinforcing ribs, dents will occur.
Material molding shrinkage
PS0.002 ~ 0.006
PP0.01 ~ 0.02
PE0.02 ~ 0.05
1. When the temperature is reduced so that no dents are generated, if there is still pressure in the material in the mold cavity, it should be considered that no dents will be generated. The pressure of the material surrounding the mold in the mold, that is, the static pressure, is not necessarily anywhere. The pressure near the gate is high. If the through edge of the material is wide, the pressure difference between the near gate and the place far away from the gate is very small compared with the overall pressure because of the pressure transmission to all corners. It is also possible to obtain a product with no internal stress remaining. However, when some materials flow into a place where it is difficult to flow, there is a high pressure in this place, and the pressure drop in other places will cause dents. This part of the high-pressure residue is the internal stress of the product is also large. In the ideal state, the temperature of the material rises with the temperature of the mold, the material fluidity is better, and the injection also changes to the bottom in the static pressure state.
2. When changing the molding conditions, the combination of temperature, pressure, and time should be prepared in advance and performed in order to know the results early. First of all, after a long time, it is easy to know every small change in pressure. It should be noted that the results obtained when the temperature changes should be obtained after injection of the material and after the temperature drops.