In injection molding processes, mold temperature control is a determining factor for product quality, process repeatability, and cycle time optimization. Industrial chillers are machines dedicated to the production and maintenance of a temperature-controlled cooling fluid, which is then circulated in the mold cooling circuits. Effective and stable cooling allows for uniform solidification of the plastic material, reducing deformation, internal stresses, and production waste.
Necessidades:
Coolant temperature control
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Heat transfer fluid pressure control
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Necessidade:
Coolant temperature control
In industrial chillers, the temperature of the cooling fluid must be maintained within well-defined limits to ensure uniform cooling of the mold.
Accurate temperature control allows for homogeneous solidification of the plastic material, reducing deformation and surface defects. In many applications, it is also necessary to compensate for excessive cooling by means of auxiliary heating in order to maintain the fluid within the optimal process range even under variable operating conditions.
Gefran’s unidade de controle térmico control technology is based on solid state relays, PID controllers, and thermocouples:
- Each resistor is managed in a closed loop via PID control, integrated in the PLC or entrusted to dedicated controllers such as the 1850, which allows the temperature to be maintained within ±0.5°C of the setpoint
- The compact GRP-H solid-state relay with integrated heat sink ensures precise current control up to 120 A. IO-Link communication also reduces the number of I/O cards required, thanks to the integrated management of commands, alarms, and current consumption
The solution is scalable and compatible with PIDs integrated in PLCs or remote modules. Recipe storage and historical trend functions support rapid production changes and continuous quality improvement.
Necessidade:
Heat transfer fluid pressure control
Inside a Temperature Control Unit, the heat transfer fluid is circulated in a closed circuit to molds, tools, or process utilities.
Circuit pressure control is essential to verify the correct operation of the pump, the absence of obstructions, leaks, or cavitation, and to ensure uniform fluid distribution. Abnormal pressure variations can indicate incorrect operating conditions and compromise the effectiveness of temperature control, as well as posing a potential risk to the machine and the process.
Solução:
KS pressure sensors are ideal for monitoring pressure in unidade de controle térmico heat transfer fluid circuits, thanks to their compact design and reliable performance over time. Continuous pressure measurement allows control thresholds to be associated with machine logic, improving system protection and operational stability.
Main features:
- Wide measuring range: from 4 to 1000 bar, suitable for various hydraulic and thermal circuits
- Thick Film technology: stainless steel membrane for high strength and durability
- Integrated snubber: mechanical structure integrated into the sensor to prevent water hammer from damaging the instrument
- Safety and diagnostic functions: SIL2 certification and IO-Link version (KS-I) for advanced circuit monitoring
Safety and diagnostic functions: SIL2 certification and IO-Link version (KS-I) for advanced circuit monitoring
Operating principle:
Industrial chillers operate by cooling a heat transfer fluid, typically water or water/glycol mixtures, through a refrigeration circuit consisting of a compressor, condenser, expansion valve, and evaporator. The cooled fluid is stored and then sent, via a circulation pump, to the molds or process utilities of the injection molding machine.
The fluid temperature is continuously monitored by temperature sensors and compared with the setpoint. The control system regulates the operation of the refrigeration circuit to maintain the temperature within a narrow range, ensuring cooling stability even in the presence of thermal load variations. In many applications, an auxiliary heating system is also provided to prevent the fluid temperature from falling below the optimum process value.
In this case, controlled electric resistors compensate for excessive cooling, ensuring continuity and precision of thermal control.
Requirements and technology:
In mold cooling, the ability to maintain a stable and controlled fluid temperature is essential to reduce cycle times and improve the quality of the molded part. The chiller must ensure a rapid response to thermal load variations, avoiding both overheating and excessive cooling that could compromise the molding process. In this context, temperature control is not limited to cooling alone , but also includes the management of auxiliary heating to keep the fluid within the optimal range.
At the same time, controlling the pressure of the cooling circuit is essential to ensure uniform distribution of the fluid in the mold channels and correct operation of the pump, preventing cavitation, leaks or heat exchange inefficiencies. The integration of reliable sensors and control systemsincreases the reliability of the chiller, supports preventive maintenance, and improves the operational continuity of the plant.
Gefran offers temperature control and pressure monitoringsolutions designed to meet these requirements, ensuring precision, safety, and integration in mold cooling systems.