The components are treated inside the furnace for 20 hours, at temperatures of up to 1400°C, then plunged into a quench tank within one minute at the end of the cycle. The heat treatment process is regulated, requiring accurate measurement, tight control and reliable data acquisition to meet its stringent standards.
The old automation system was controlled by an obsolete 19” rack PLC which had become unsupportable and due for replacement. The traditional PLC’s PID control and programmer were very basic, so the furnace had always suffered from temperature overshoot. Data acquisition had been carried out via PC/SCADA, in the insecure CSV file format, and as the programmable logic controller was not capable of internal recording, the data could be lost if communications were interrupted.
The end user’s requirement included multiple control loops, 99 programs, 96 digital inputs, 48 digital outputs, data acquisition and a number of HMI screens with web browser access. Eurotherm control was the system integrator’s preferred choice, due to specialized PID control strategies, intelligent autotune, and advanced setpoint programming which, according to their engineering manager are “far superior compared to other PLCs and controllers”. Up until now, they had been using a third party programmable logic controller with separate Eurotherm precision PID controller to replace this kind of system but wanted to move to an all in one solution.
In this scenario, the E+PLC400 modular platform with E+HMI150 touch panel was their preferred solution, offering multiple control loops, setpoint programmers and segments, in combination with batch recording and PLC functionality. CODESYS® integrated development environment was also a familiar tool for the system integrator engineer.