TECHNOLOGY | TEMPERATURE CONTROL
Figure 1: The steam pressure curve illustrates the connection between the water inlet pressure and the maximum operating temperature
Right: HB-Therm temperature controllers
motors. Moving from a 1.1 kW IE2 to IE3 motor can increase efficiency from 79-79.6% to 82-82.7%. The SpeedDrive option consists of a pump equipped with a permanent-magnet synchronous motor. In combination with a matching frequency converter, this configuration reaches an efficiency rating of more than 86%, which corresponds to efficiency class IE4. In this way, the power consumption of the motor can be reduced by up to 30% when other operational parameters of the pump (working pressure and flow) remain unchanged. Additional savings can be achieved by lowering the working pressure of the pump through reducing the motor speed, which cuts the pump’s power input and consequently the power consumption even further. The differential temperature is influenced by mould design (number, diameter, length and geometry of the tempering channels) and the type of connection to the mould (diameter and length of the tubes between the temperature controller and the mould, as well as serial or parallel flow through the tempering channels). The differential temperature is an important indicator of the thermal balance of a mould and the homogeneity of temperature distribution inside the cavities, and it should be pre-defined for every mould, depending on the product to be manufac- tured. Once the differential temperature has been calculated for a given application, it can be set as a fixed parameter for the Tempro with SpeedDrive and monitored by defining toler-
50 INJECTION WORLD | June 2018
ance margins. In the event of any change in the injection moulding machine’s process parameters which have an effect on the cycle time, the TCU responds to such a change by increasing or reducing the motor speed of the pump to maintain the set differential temperature. HB-Therm has developed TCUs using water – not synthetic oil – as heat transfer fluid to cool plastic moulds at operating temperatures of 200-230°C (392-446°F). The water HB-Therm TCUs are claimed to deliver precise cooling while eliminating environmental concerns associated with oil TCUs, which are often used to achieve high operating temperatures. Additionally, water as a heat transfer fluid is an inherently safer option than synthetic oil. Frigel is introducing the TCUs to the North American market as exclusive distributor for of HB-Therm. The high-temperature water HB- Therm TCUs complement the company’s existing line of water TCUs rated to deliver and maintain process cooling water from 100-180°C (212- 355°F). The portable HB-Therm units are compact with footprints of 1.3-3.2 square feet. With the HB-Therm racking system, users can stack multiple units together to deliver precise cooling to as many as eight mould zones and with an available central control module for as many as 16 separate zones. Frigel has introduced a CT option for its line of
Microgel combination chiller/temperature control- ler, allowing them to work easily with open cooling towers. The new development allows all plastics processors the ability to use the chiller/TCUs to improve productivity, profitability and quality – not just those who use a Frigel Ecodry closed-loop adiabatic central cooling system as a preferred process cooling water source. The company says Microgel can deliver better part quality, less scrap and improve typical cycle times by up to 20%. The CT option filters out potential open- cooling tower water contami- nants supplied to Microgel units, which it says are ideal for machine-side process cooling. It also alerts users to potential problems with contaminated cooling tower water to ensure maximum uptime of the chiller/ TCU. Previously, Frigel recom- mended the use of Microgel units only with an Ecodry central cooling system because it is a closed-loop, clean water system. The CT option is available on the Microgel RCM, RCD and RCX models.
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