The temperature control system consists of three components:
- heating-cooling channel in the mold,
- coolant and
- temperature control unit
To achieve optimal mold temperature control, the three components must meet certain conditions:
- Position of the heating-cooling channels
The number and position of the heating-cooling channels should be selected such that uniform temperature control of all molding sections is ensured and an adequately large heating-cooling channel surface is available. Adaptation of the temperature control must be provided for, especially for molding corners and cores (angular distortion).
- Size of the heating-cooling channels
In connection with the size of the heating-cooling channels consideration must be given to the pressure needs for conveying the coolant in the mold. If the cooling channels are too small, a high pressure drop is the consequence. Diameters that are too large lead to a low flow speed and prevent a turbulent flow. However, a turbulent flow in the cooling channels is a major requirement for the effectiveness of the cooling system.
- Temperature difference
The temperature difference between inlet and outlet temperature of the coolant should be as small as possible. Therefore, a division into several parallel circuits is necessary according to the size and quality demands placed on the component so the temperature difference does not become too large.
- Coolant and temperature control unit
The coolant should have good heat transfer properties. Water has proven to be an ideal coolant for the processing of thermoplastics. The temperature control unit must be able to maintain the desired mean mold wall temperature within tight limits regardless of the production conditions.
- Angular distortion due to temperature differences