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In this context, temperature control refers to the water needed for the heating or cooling of tools and dies, as well as the cooling of heat-generating equipment such as hydraulic circuits.
In the case of tools and dies, the most frequent requirement is for chilled water. This is pumped around channels (water-ways) within the tool’s steel walls to speed up the solidification of the plastic within. In the case of injection moulding, it is also sometimes necessary to heat up one half of the tool using heated water or oil within the channels, to prevent the plastic from solidifying (chilling off) too quickly during the injection phase.
Temperature control units (TCUs), also known as thermoregulators or water heaters, are used to control the temperature of a fluid that circulates around the channels that require temperature regulation. A good example would be an injection mould tool that contains water-ways. Most TCUs use water, hence they are sometimes also called water heaters. If they use a pressurised water system, temperatures can be increased from the standard ceiling of around 90°C to around 140°C. For higher temperatures, TCUs that use oil as their circulated medium are capable of achieving around 350°C. In this case, specialised distribution hoses are also needed.
Industrial chillers are used to reduce the temperature of the water that is used for the cooling of moulds or the hydraulic circuits of processing machinery. In the case of moulds, chillers are used where it is necessary to remove excess heat, for example to achieve a fast cycle time when producing thin-walled products.
The chiller uses refrigerants and a pumping system to maintain a pre-set temperature within a water circuit. Smaller units can be used for individual moulds or machines, whereas larger units can be used for a ‘ring-main’ type system.
Free coolers are designed to reduce the temperature of water in a factory ring-main back to close to ambient levels. They are in effect giant radiators, similar to those used to cool a car engine’s oil. Machine hydraulic circuits don’t need chilled water, just water that is cooler than the oil in their heat exchangers.
Free coolers are typically sited outside a factory and in shade. This means that for a significant amount of time, it is only necessary to pump water around the circuit. In hot weather, electric fans engage to increase airflow across the radiator fins.
There are two basic types of free cooler: