The temperature distribution in the cavity has a great influence on the deformation and internal pressure of the part. Reasonable setting of cooling passage can reduce the internal pressure and improve the quality of injection parts. It can also shorten cycle time and reduce product cost. Secondly, the mold temperature machine must be able to keep the temperature of the heat conducting fluid in the range of 1-3 C, which is determined according to the quality requirements of the injection parts. Thirdly, the heat conducting fluid must have good heat conductivity, and most importantly, it should be able to import or export a large amount of heat in a short time. From the thermodynamic point of view, water is obviously better than oil.

The working principle of the model temperature machine is composed of water tank, heating and cooling system, power transmission system, liquid level control system, temperature sensor, injection port and other devices. Usually, the pump in the power transmission system makes the hot fluid from the water tank with built-in heater and cooler to the mould, and then from the mould to the water tank; the temperature sensor measures the temperature of the hot fluid and transmits the data to the controller of the control part; the controller adjusts the temperature of the hot fluid, thus indirectly adjusting the temperature of the mould.