The need for temperature regulation of injection molding molds

The temperature of the injection molding mold has a great influence on the flow of the plastic melt, curing and shaping, production efficiency, and the shape and dimensional accuracy of the plastic parts.

Each kind of plastic injection molding has a reasonable mold temperature region so that the melt flowability is good and easy to fill the cavity, the shrinkage and warpage deformation of plastic parts after release from the mold is small, the size is stable, and the mechanical properties and surface quality are also high. In order to control the temperature of the mold, the temperature regulation system must be designed, generally using the method of mold cooling or heating, if necessary, both, the cell phone shell mold using cooling devices more.

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 filling the cavity and getting the high-quality surface of rubber parts, but it will make the curing time of rubber longer and easy to deform when ejecting;

For the crystalline rubber, it is better for the crystallization process to avoid the change of the size of the rubber part in storage and use; in the mold with lower temperature, it is difficult for the molten rubber to fill the cavity, which will lead to the increase of internal stress, the surface is not glossy, and the defects such as silver pattern and fusion marks are produced.

Different rubber materials have different processability, and the surface requirements and structure of various rubber parts are different. In order to produce the rubber parts in the most effective time to meet the quality requirements, which requires the mold to maintain a certain temperature, the more stable the mold temperature, the more consistent the requirements of the produced rubber parts in terms of size and shape, and the appearance quality of the rubber parts.

Therefore, in addition to the factors of mold manufacturing, mold temperature is an important factor to control the quality of rubber parts, and the mold design should fully consider the mold temperature control method.

2 . Principle of mold temperature control

In order to ensure the production of high appearance quality, dimensional stability, and small deformation in the most effective time, the basic principles of mold temperature control should be clearly understood during the design.

1) Different rubber materials require different mold temperatures.

2) Different surface quality and different structures of the mold require different mold temperatures, which requires targeting in the design of a temperature control system.

3) The temperature of the front mold is higher than the temperature of the back mold, and the temperature difference is about 2~3º in general.

4) The temperature of the front mold with the requirement of sparkle pattern is higher than the temperature of the front mold with the requirement of general glossy surface, and when the front mold has to pass hot water or hot oil, the temperature difference is generally about 40º.

3) When the actual mold temperature can not reach the required mold temperature, the mold should be heated up, so the mold design should fully consider whether the heat brought into the mold by the rubber can meet the mold temperature requirements.

6) The heat brought into the mold by the rubber material should be consumed by heat radiation and heat conduction, but most of the heat should be brought out of the mold by the circulating heat transfer medium.

7) The mold temperature should be balanced, and there should be no local overheating or overcooling.