User guide

TrueFeed manual
39
8. System performance
System performance can be characterized by the time it takes the unit to reach the desired set point, the
accuracy of the set point and the consistency of the material output.
The algorithm is self-adjusting to the conditions and because the conditions vary, it cannot be predicted how
long it will take the unit to adjust itself and reach a set point with certain accuracy.
The following variables influence system performance:
Material properties. Easy flowing, non-sticky and non-static material that comes in the form of small granules
or powder can be dosed very accurately and consistently. The accuracy and consistency of the material output
drops with increased granule size. However, this is only a problem with extremely low outputs.
Periodical cleaning of the dispensing cylinder and seals is required for proper operation.
Extreme vibrations and shocks influence the system’s performance noticeably. Normally, the system will be
able to compensate for vibrations and shocks.
The TrueFeed algorithm needs a certain time to weigh material loss and adjust the RPM accordingly. This time
depends largely on the set point and the above mentioned three variables. The system constantly adjusts itself
to reach the best possible accuracy for current conditions. Over time it can reach an accuracy within ± 1%.
Under “normal” circumstances the unit will be more accurate than 10% after the first adjustment of the RPM.
Before the unit makes its first RPM adjustment it may be running already very close to the desired set point
because it uses a cylinder and material reference system to determine the first RPM setting. This accuracy
however cannot be guaranteed because material properties can vary substantially from material to material.
With injection molding the shot-to-shot accuracy depends, besides the variables mentioned so far, on the shot
time. If large and heavy granules have to be dosed in a very short time this will influence the shot accuracy and
repeatability because one granule can make a difference of a few percent to the shot weight.
An unstable relay or tachometer signal has a negative effect on the accuracy, repeatability and speed of the
system because it will adjust to these parameter changes.
A long cycle time combined with low dosage per shot can result in a slow system.
8.1 Reset regulation
• Changing one parameter during production will cause the TrueFeed to adjust to the changes, but it will
not reset the regulation totally.
• Changing more production parameters during production within 10 seconds after each other will cause
the TrueFeed regulation to reset. This is necessary for the system to adjust quickly to large changes in
the settings.
• Turning the power OFF and ON again will also cause the regulation to reset.
• Motor OFF and ON again will only cause the regulation to pause. The start up RPM will be the same as
the last RPM before the stop.
• Changing one parameter with the motor OFF causes total reset of the regulation.
• With auto start = ON (CONFIGURATIONS menu) the motor follows the last status (motor Standby or
motor Stop status) and causes total reset of the regulation.