Plastic injection mould tooling temperature control
The temperature of the injection mold has a great influence on the material filling flow, curing setting, production efficiency, shape and dimensional accuracy of the plastic molding.
Each plastic injection molding material has a reasonable mold temperature area, so that the fluidity of the material is easy to fill the cavity, the shrinkage and warpage of the plastic parts after demolding are small, the size is stable, and the mechanical properties and surface quality are also high. In order to control the temperature of the mold, it is necessary to design a temperature adjustment system, generally using a mold cooling or heating method, if necessary, both, and more cooling devices are used in the casing of the mobile phone casing.
1. The necessity of temperature adjustment
The mold temperature has a great influence on the molding quality and molding efficiency of the rubber or plastic parts. In the mold with higher temperature, the fluidity of the molten plastic is better, which is beneficial to the filling of the cavity of the raw material, and obtains the appearance surface of the high-quality parts, but the curing time of the plastic material becomes longer, and it is easy to be deformed when being ejected. For crystalline plastic compounds, it is more conducive to the crystallization process, avoiding the change of the size of the plastic parts during storage and use; in the mold with lower temperature, the melting resin is difficult to fill the cavity, resulting in increased internal stress and matte surface. Produces defects such as silver streaks and welding lines.
Different plastic compounds have different processing techniques, and the surface requirements and structures of various rubber parts are different. In order to produce the rubber parts that meet the quality requirements in the most effective time, the molds are required to maintain a certain injection temperature and mold temperature. The more stable, the more consistent the requirements for the size and shape of the plastic parts produced and the appearance quality of the plastic parts. Therefore, in addition to the factors in mold manufacturing, the mold temperature is an important factor in controlling the quality of the plastic parts. The mold temperature should be fully considered in the design of the mold.
2. Principles of mold temperature control
In order to ensure that the plastic parts with high appearance quality, stable size and small deformation are produced in the most effective time, the basic principles of plastic injection mould tooling temperature control should be clearly understood during design.
1. Different compounds require different mold temperatures. please reference the material date sheet for mold temperature.
2. Different surface quality, different structure of the mold requires different mold temperatures, which requires specific design when designing the temperature control system.
3. The temperature of the cavity side is higher than the temperature of the core side. Under normal circumstances, the temperature difference is about 2~3℃.
4. The mold temperature required for the texture pattern is higher than the mold temperature required for the general smooth surface. When the current mold is required to pass hot water or hot oil, the general temperature difference is about 40℃.
5. When the actual mold temperature can not reach the required mold temperature, the mold should be heated. Therefore, the mold design should fully consider whether the heat brought into the mold can meet the mold temperature requirements.
6. The heat that is brought into the mold by the rubber is consumed by heat radiation and heat conduction, and most of the heat needs to be carried out of the mold by the circulating heat transfer medium.
7. The mold temperature should be balanced, and there should be no partial overheating or too cold.
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