Thermal growth compensation has become fairly routine among laser aligners. For machines that run at high temperatures, most manufacturers will recommend a target to align to that compensates for the thermal growth that the machine is expected to undergo. That target only tells half of the story though. In many of the situations we see, once operating, there may be more horizontal movement than vertical, and both movements are often far different from the specified amounts. These differences usually arise from sources such as pipe stress, foundation looseness, operating load variances, and other factors.

To ensure perfect alignment under operating conditions, you can monitor the positional change of machines at your plant using the ROTALIGN® ULTRA and Live Trend module. During your next shutdown, mount the lasers to the machines and monitor the cooldown. During the shutdown, align the machines using your newly discovered targets and even verify the accuracy by re-measuring the positional during start-up and run-up to final operating condition.