Resolving Strip Alignment and Tooling Wear on a Tube Mill Line

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: 
An evaluation of a tube mill line was requested to address chronic issues related to strip tracking, weld inconsistencies, and roll life. Operators reported that the payoff system frequently caused strip camber, leading to problems downstream in the weld and sizing sections. The line’s tooling, in many cases, was also worn or mismatched, contributing to unstable formation and irregular profiles.

Challenge: 
Several contributing factors were discovered during the inspection. The uncoiler's arbor cylinder was leaking, causing coil loosening and uneven strip payoff. Additionally, the strip consistently skewed to the inboard side, forcing operators to use overhead arms to manually center it, which increased drag and damaged strip edges. The braking system lacked sufficient control and had no provision to stop coil unwinding during shutdowns, which further stressed the accumulator and end weld station.

In the end welder, strip clamps were bent and the base was worn, leading to poor holding pressure. The shear cylinder lacked full travel, resulting in incomplete cuts on wider coils. Tooling across the breakdown and fin sections was badly worn. Several driven shafts had dropped below the minimum O.D. tolerance, and the side pass stands lacked adjustment features to maintain consistent vertical and lateral positioning. Side pass rolls were not being used in the sizing section due to locking and wear issues, eliminating their stress-relieving and sizing function.

Solution: 
A complete set of mechanical upgrades and procedural recommendations was presented. These included retrofitting the uncoiler with a modern caliper braking system with both run and stop pressure settings, and consideration for replacing it with a double payoff unit for continuous production. Entry guides and end welder components were to be replaced with hardened tooling and realigned to ensure consistent end weld preparation. The first breakdown stand was to be powered to reduce downstream stress and aid with threading.

Roll-Kraft also recommended replacing undersized shafts with either new 4140 material shafts or chromed restorations. All driven bearings were to be preloaded using torque-wrench procedures, and jam nuts were advised to prevent damage from impact tightening. Tooling wear documentation, improved coolant filtration, and implementation of SPA features across more stands were also advised. Lastly, technicians emphasized the importance of reintroducing side pass rolls with sealed bearing designs — essential for final tube straightness and proper sizing.

This systematic approach helped restore mechanical precision and strip alignment, directly supporting higher weld quality and tooling longevity.

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.