Shaft Wear and Setup Chart Gaps Disrupt Tube Mill Consistency

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: 
During a two-day field service visit, Roll-Kraft was asked to evaluate two mill lines running under the same roof. The operators had expressed concern about inconsistent sizing results, premature tooling wear, and the inability to reproduce past setups. These symptoms pointed to deeper mechanical and procedural issues affecting shaft integrity and roll setup procedures.

Challenge: 
Several critical issues emerged during inspection. First, many of the driven shafts were severely undersized — one shaft in particular was over 0.040" below spec — creating excessive play between the shaft and roll bores. Additionally, many keyways were worn or broken, further degrading torque transfer and tooling stability.

Another major concern was the inconsistent or missing data on existing setup charts. Roll-Kraft found that many side rolls lacked dimensional targets or metal line specifications, making it nearly impossible for operators to set up the tooling as originally designed. The absence of this information led to unpredictable formation and contributed to the wear of both rolls and shafts.

The mills also lacked top tie bars on many side pass stands, which meant there was no way to ensure the side rolls remained parallel during adjustment. In several cases, technicians discovered top and bottom shafts out of phase, leading to mismatched RPMs and roll slippage. Basic setup tools like straight edges and plug gauges were also missing from the floor, compounding setup inconsistencies.

Solution: 
Roll-Kraft recommended the immediate replacement or chroming of all shafts found to be out of tolerance, with attention to matching O.D. and keyway integrity. A shaft inspection guideline and preload torque procedures were provided, along with links to training videos and technical publications.

To address charting gaps, operators were advised to contact tooling vendors for full dimensioned setup data, including metal lines and tube profile targets for each pass. Roll-Kraft offered support in developing complete setup charts from existing tooling. Side pass stands were to be retrofitted with top tie bars to ensure proper roll alignment, and plug gauges were recommended for weld box and Turks head unit.

Finally, it was advised that both mills undergo complete optical alignment after mechanical upgrades, and that all operators and maintenance staff download Roll-Kraft’s online PM guides and setup tools for ongoing reference.

Contact Roll-Kraft for a Tube & Pipe Mill Evaluation
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