Precise Optical Alignment Improves Mill Stability and Roll Fit

Over the years, Roll-Kraft has conducted thousands of mill evaluations on a variety of equipment. We are now sharing these stories in our Tube & Pipe Field Service Report Article Series. We hope you find the information contained in this series helpful. If you have any questions regarding your mill, use our contact form to request more information about our on-site mill evaluation.

Problem: 
Operators of a tube mill line had reported persistent product inconsistencies despite installing new driven shafts and bearing blocks. They sought assistance in confirming the mechanical alignment of the mill and ensuring their recent upgrades would hold tolerances during production. While the line had been well-prepared for service, operators noted difficulty maintaining consistent roll contact across the forming and sizing sections.

Challenge: 
Roll-Kraft performed a full optical alignment over a four-day service visit. Using a optical scope and straightedge verification, technicians assessed the alignment of the driven shafts from the first breakdown through the final sizing pass. While the newly installed shoulder spacers were initially uniform, variations began to appear as readings were taken. Several top shafts required correction of up to .100", and some bottom shafts were out as well.

The roll space for the breakdown stands had to be shifted outward by roughly .250", requiring retapping of the outboard stand mounting holes to realign the outboard sleeve. The inboard towers were parallel, but soft alignment spacers were found to compress over time, risking shoulder misalignment. Within the cage area, the framework was aligned, but some inner "football" rolls required repositioning to center the strip correctly around the edgeform.

Additional challenges included missing tie bars in the sizing section that allowed the side rolls to spread open under load, and spline connections showing wear that could compromise adjustment repeatability.

Solution: 
With the mill base in excellent condition, the team proceeded with installing corrected shoulder spacers, including custom-ground pieces verified with the alignment scope. Hardened ground spacers were recommended as replacements for soft spacers to prevent compression and improve longevity. The tooling department was advised to fabricate permanent spacers from D2 hardened material.

Alignment of the cage framework and scarf stand was confirmed using a custom plug bar, and adjustments were made to clevis plates to align the inside guide rolls with the newly established metal line. Outboard spacers were standardized for repeat setups, and the team confirmed zero marking or strip damage while running product at the end of the service.

Operators were trained to adjust the side roll tie bars and encouraged to replace the current top bars with a more rigid design to prevent flare. Lastly, the mill was outfitted with digital readouts and shoulder alignment tools to assist in future checks and ensure consistent positioning across all driven shafts.

Contact Roll-Kraft for a Tube & Pipe Mill Evaluation
Do you have issues you would like a second opinion on regarding your mill? Roll-Kraft on-site evaluations really make an impression with your staff, confirming you are serious about producing quality tube, pipe, and roll form products. Our technicians will tell you exactly where you are currently doing a great job, in addition to pointing out any areas that could be improved. We have been doing training and evaluations for over 30 years and understand the sensitive nature of bringing someone in to talk about improvements. Your staff will be in good hands with Roll-Kraft. Click here to learn more about our tube & pipe evaluation service.