Temperature overshoot occurs when control output continues after the process has received enough energy to pass the setpoint. It is common during startup, after long stops, after a tool change, or when sensor response is slower than the heated mass.
Setpoint, process value, controller output, and actual sheet or mold temperature should be trended together. Overshoot that changes with load may indicate poor tuning, sensor location, output staging, or a failed power device rather than one universal PID setting.
Tuning should be performed for the real thermal system with safe output limits and startup logic. Ramp-and-soak control, staged heater enable, or separate startup parameters may be appropriate. Reducing the setpoint to compensate for overshoot leaves the steady process underheated and should not be treated as a permanent solution.