Acoem alignment systems allow the user to input thermal growth (offline to running) targets prior to performing a precision shaft alignment. Using targets allows the alignment to be completed to tolerance and the thermal growth will be compensated for. The real key to success, of course, is determining good targets. These are best obtained via actual measurement such as using OL2R (offline to running) brackets. Additional information on offline to running movement is covered in other blog posts and videos. Learn more by checking out the links at the bottom of the page.
Growth Dynamic Movement
Growth (dynamic movement) is how machines move relative to each other once put into operation and targets are the compensation for said growth when performing alignments with the machines offline and at ambient temperature.
Understanding the Effect of Entering Targets
For purposes of explanation, a set of measurements were taken on a straight shaft (not across a coupling). Since the shaft is a common centerline, the system will zero. When aligning real machines, targets would typically be entered prior to taking alignment measurements, but in this example they will be added after so the effect of entering the target(s) can be better understood.
System Zeroed out.
Touch the machine icon and you see a thermometer. Touch the thermometer to enter targets.
Adding Targets as Feet Values or Angle and Offset
Targets can be added as feet values or as an angle and offset at the coupling. If the goal is to leave the motor 5 thousandths high, add the target of + 5 at the front and rear feet of the moveable machines or as +5 at the coupling with a zero angle. These would be equivalent. Although this example is showing just a vertical offset, in most cases where actual measurements were made, you will likely have a vertical angular component and often horizontal movement.
Compensation for Expected Growth
With the targets added the laser is showing that instead of zero the motor is now 5 thousandths low. This represents the compensation for the expected growth. When the alignment is completed, the motor will be 5 thousandths high with the expectation that the stationary machine will grow to meet the motor and will be aligned within tolerance at operating conditions. Note that a thermometer is shown next to the motor in the vertical plane to indicate that the alignment is done to targets.
Report of Completed Alignment with Targets
When an alignment is completed on a machine with targets the final report will show the completed alignment with both the tolerance and targets.
Additional Resources
Basics of Thermal Growth Video
