Mold and Temperature Control
A mold temperature control unit is a device that keeps the mold temperature constant at the set value by circulating water or oil through the mold's cooling channels. Water-based units reach 90–160 °C under pressure; oil-based units reach 200–300 °C. Because mold temperature directly determines part surface quality, degree of crystallinity, shrinkage and cycle time, the temperature control unit is the most influential auxiliary equipment in injection molding.
"Cooling" the mold and "conditioning" it are not the same thing. A chiller cools the mold; a temperature control unit holds the mold at the target temperature — heating it when necessary, cooling it when necessary. Most engineering plastics (PA, PC, POM, PPS, PEEK) require the mold temperature to be kept in the 60–200 °C band; in this band the task is controlled heating, not cooling.
Water boils above 100 °C; pressurized water units keep the circuit under pressure and work with water up to 140–160 °C. Anything higher requires oil; the price of oil is lower heat transfer, oxidation and sensitivity to leaks. The rule "do not move to oil unless you have to" comes from this.
When selecting a unit, heater power, pump flow rate and pressure and the number of circuits are as decisive as the temperature range. Turbulent flow (high flow rate) is wanted in the mold channels; increasing the flow rate is usually more effective than making the water colder.
The two do different jobs. A chiller produces cold water (5–20 °C); if the mold temperature is to be held high, a temperature control unit is required. In most plants the chiller supplies the cooling water of the temperature control unit, and the two work together.
If the mold temperature is below 160 °C, water; if above, oil. Water transfers heat better, and is cleaner and cheaper. With materials that require a mold above 170 °C, such as PEEK, PPS and LCP, oil is unavoidable.
Yes. With OPC UA, Profinet, Modbus and analog signal options, the set value and actual temperature can be monitored and recorded from the machine screen; EUROMAP 82.1 standardizes this interface.