Typical Pid Values; Possible Causes Of Oscillation - Husky Altanium Matrix2 User Manual

User Guide

7.7.1 Typical PID Values

The following is a list of some typical PID values.
Table 7-6
Proportio

7.7.2 Possible Causes of Oscillation

It is possible to set the control terms incorrectly, inducing an oscillation. The following are the
most common causes:
Table 7-7
"P" too large
"I" too large
"D" too large
Shear
Typical PID Values
PID Values
Integra Derivativ
nal l
015 010 002
050 020 000
020 010 000
015 015 000
020 007 100
020 005 200
100 003 000
075 003 150
Possible Causes of Oscillation
Cause
Power change too great per °C of temperature change.
Power changing too quickly for the process to follow it.
Stepped power change too large for the rate of change of temperature.
An important issue often overlooked is the effect of shear in the material as
it passes through the gating area. This can cause rises in temperature in
excess of 33 °C (60 °F) under severe conditions. Therefore, if large
temperature variations occur during molding, it is worth plotting this
variation against the molding cycle time. As the controller cannot initiate
additional cooling, it is only possible to minimize this effect with properly
selected PID terms.
v 1.1 — July 2015
Type
e
Fast Probes or heaters with internally located
thermocouples
Fast
Fast
Fast
Medium Probes or heaters with internally located
thermocouples (larger mass)
Medium
Slow Manifolds or heaters with externally located
thermocouples
Slow
Description
Making Adjustments
Example
83