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During the injection molding of plastic molds, there will be some adverse situations, common like top white, shrink, dent ... then in this case, how to solve it, need to analyze the cause of adverse, thus a targeted solution Phenomenon.
First, dent
The reasons for generating dents during the injection molding process are:
The reasons for generating dents during the injection molding process are:
1. The mold cools are insufficient, and the cooling time can cause serious deformation.
2. This is also in the mold in the mold.
3. The thickness of each part of the article is different. In this case, the overall treatment method: reducing the tube temperature and mold temperature, in the place where the dent is caused, the dent is completed, and the difference in the thickness of the controlled design article.
4. Too thick place will have a depression due to large shrinkage. Treatment method: By increasing pressure, increasing the pressure time, the depression can be reduced or even eliminated, and the key to the degree of depression, and whether the manufacturer is willing (the preserved will reduce productivity).
In summary, the lands produced during the injection molding process of plastic molds, the main solutions are as follows:
1. Improve the injection energy: pressure, speed, time, and material, and improve back pressure, make it full.
2. Increase the smooth flow of temperatures. Reduce the temperature reduction shrinkage, appropriately increase the mold temperature, in particular, to form partial molding of the true void portion.
3. Set the gate in part of the body, improve the flow of nozzles, flow paths, and gates, reduce the consumption of pressing.
4. Improve the mold exhaust situation.
Second, the associated knowledge
1. During the production of the product, the dent is the highest frequency in the poor phenomenon, and the plastic injected into the mold occurs in the cooling. The early cooling portion is first hardened, and the inside will generate bubbles. The so-called lant is cooling. The slow portion produces a prominent concave surface in the direction of bubble contraction.
1. During the production of the product, the dent is the highest frequency in the poor phenomenon, and the plastic injected into the mold occurs in the cooling. The early cooling portion is first hardened, and the inside will generate bubbles. The so-called lant is cooling. The slow portion produces a prominent concave surface in the direction of bubble contraction.
2. Materials with large shrinkability are also prone to dents. When it is necessary to change the molding conditions to eliminate the dents, the setting condition should be set to the direction of receding. That is, the mold temperature, the tube temperature is lowered, and the injection pressure is increased, but it should be noted that the residual internal stress may be caused.
3. Because the dents are good in unrestrained, if it does not affect the appearance, it is intentionally processed into corrosion on the mold, such as striped, granular, and the like. Also, if the molding material is HIPS, it also has an effect with reduced molding. However, once there is a dent, it is difficult to repair the polishing product.
Third, the method of solving
1. Immediately: Improve the injection pressure, extend the injection pressure time, reduce the tube temperature and the mold temperature, and forced cooling in the place where the dent is generated.
1. Immediately: Improve the injection pressure, extend the injection pressure time, reduce the tube temperature and the mold temperature, and forced cooling in the place where the dent is generated.
2. Short-term: Flowing edges in the place where dents are generated. This part is thick when there is a small place where the material is generated in the shape of the latter.
3. Long-term: It should be completely avoided to avoid the difference in thickness of the product. It is easy to generate a reinforcing ribs of the dent, and the narrow shape should be as short as possible.
Fourth, the difference in materials
Materials with large formation of shrinkage, laid also large. For example, PE, PP, even if a slightly reinforcing rib is slightly reinforced, there is a lash.
Materials with large formation of shrinkage, laid also large. For example, PE, PP, even if a slightly reinforcing rib is slightly reinforced, there is a lash.
The material forming shrinkage is as follows:
PS0.002 ~ 0.006
PP0.01 ~ 0.02
PE0.02 ~ 0.05
PS0.002 ~ 0.006
PP0.01 ~ 0.02
PE0.02 ~ 0.05
V. References:
1. When the temperature is lowered to the no dent, if there is still a pressure in the mold cavity, it should be considered that there is no indentation. The pressure around the mold is static in the mold, no matter where it is not necessarily. The pressure is close to the gate portion, if the side of the material is wide, since the pressure of the pressure of the respective corners, the pressure difference of the near gate is different from the pressure difference from the gate, and the pressure is different than the pressure. Traces, you can get products that do not residual internal stress. Some materials are high pressure in this place where there is a difficult place, and the pressure reduction in other places will generate dents. This part of the residual residue is that the internal stress of the article is also large. In the ideal state, the material temperature is rising with the temperature of the mold, and the material is well fluid, and is shot in the static pressure state.
1. When the temperature is lowered to the no dent, if there is still a pressure in the mold cavity, it should be considered that there is no indentation. The pressure around the mold is static in the mold, no matter where it is not necessarily. The pressure is close to the gate portion, if the side of the material is wide, since the pressure of the pressure of the respective corners, the pressure difference of the near gate is different from the pressure difference from the gate, and the pressure is different than the pressure. Traces, you can get products that do not residual internal stress. Some materials are high pressure in this place where there is a difficult place, and the pressure reduction in other places will generate dents. This part of the residual residue is that the internal stress of the article is also large. In the ideal state, the material temperature is rising with the temperature of the mold, and the material is well fluid, and is shot in the static pressure state.
2. When changing the molding conditions, the combination of temperature, pressure, and time should be prepared in advance, and the results can be known in order. The first time the time has become very long, it is easy to know the minute changes. It should be noted that the result of obtaining temperature changes should be obtained after the injection material, the like temperature is lowered after production.
Plastic molds inevitably have some adverse conditions during injection molding, need to be adjusted according to different circumstances of the dent, corresponding to the method of adjusting the injection molding machine parameters, mold or raw materials, to ensure product Can be produced normally.
