The need for temperature adjustment of injection molds

The temperature of the injection mold has a great influence on the filling fluidity, curing and shaping of the plastic melt, production efficiency, as well as shape and dimensional accuracy. Every plastic injection molding has a reasonable mold temperature zone, so that the fluidity of the melt is easy to fill the cavity, the shrinkage and warpage of the plastic part after demolding is small, the size is stable, and the mechanical properties and surface quality are high. In order to control the temperature of the mold, it is necessary to design a temperature regulation system, which generally uses the method of mold cooling or heating, or both if necessary, while the cell phone shells mostly use cooling devices.
1. The necessity of temperature regulation
Mold temperature has a great influence on the molding quality and molding efficiency of rubber parts. In the mold with higher temperature, the liquidity of molten rubber is better, which is good for the filling of rubber cavity and getting the appearance surface of high quality rubber parts, but the curing time of rubber becomes longer, and it is easy to deform when ejecting.
For crystalline rubber compound, it is more favorable to the crystallization process to avoid dimensional changes of rubber parts during storage and use; in molds with lower temperature, it is difficult for molten rubber to fill the cavities, resulting in increased internal stress and a lusterless surface. Produces defects such as silver streaks and weld lines.
Different rubber compounds have different processing processes, and various rubber parts have different surface requirements and structures. In order to produce rubber parts that meet the quality requirements in the most efficient time, the mold is required to maintain a certain temperature and mold temperature. The more stable it is, the more consistent the requirements for the size and shape of the rubber parts produced and the appearance quality of the rubber parts.
Therefore, in addition to the factors in mold manufacturing, mold temperature is an important factor in controlling the quality of rubber parts. The mold temperature should be fully considered in the mold design.
2. Principle of mold temperature control
In order to ensure the production of high quality, high quality, dimensionally stable, low-profile rubber parts in the most efficient time, the basic principles of mold temperature control should be clearly understood in the design.
1 Different compounds require different mold temperatures.
2 Different surface quality and different structure of the mold need different mold temperature, which requires targeting when designing the temperature control system.
3 The temperature of the front mold is higher than the temperature of the back mold. Under normal conditions, the temperature difference is about 2-3o.
4 The temperature of the front mold required by the fire pattern is higher than the temperature of the front mold required by the general smooth surface. When the present die is required to pass hot water or hot oil, the temperature difference is generally about 40o.
5. When the actual mold temperature cannot 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 requirements of the mold temperature.
6 The heat brought into the mold by rubber is consumed through heat radiation and heat conduction, and most of the heat needs to be brought out of the mold through the circulating heat transfer medium.
7 The mold temperature should be balanced and there should be no local overheating or excessive cooling.