Manual Setting of Melt Pressure Controllers
Extreme care must be taken when setting the melt pressure controller on an extruder, otherwise damage to the extruder may occur.
Extreme care must be taken when setting the melt pressure controller to an extruder, otherwise damage to the extruder may occur.
Standard autotuning controllers cannot be used because they make a step change at the controller output, then monitor the process value (pressure). Extruder drives cannot handle a sudden change in output without any damage.
Standard manual adjustment methods cannot be used either because they involve step-by-step changes.
Fortunately, most melt pressure controller loops can be adjusted by starting with a set of values and making minor changes.
Starting Values
Proportional band: 60% Aperture
Integral: 15 seconds
Derivative: 0 seconds
Input Filter: 2sec
Ascent rate limiter: 15 seconds for 100% change
Successful Tuning Steps
Enter the initial values; the loop must be very stable
Enter changes in pressure set point; observe
If control is too slow to respond, reduce PB to 50%
Check by entering the setpoint changes; observe
If control is too slow to respond, reduce PB to 40%
Check by entering the setpoint changes; observe
If control is too slow to respond; Decrease integral to 9s
Check by entering the setpoint changes; observe
Continue reducing until you get the desired response
If the initial settings are unstable, increase the input filter to 5 seconds and make PB and Integral stable
If you still have problems, contact the factory.