Addressing Drive Shaft Phasing and Bearing Integrity 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: 
During a scheduled pre-alignment visit to a tube mill operation, Roll-Kraft was asked to inspect the line for any mechanical issues that could interfere with an upcoming full optical alignment. Although the equipment appeared to be in overall good shape, there were signs of vibration, excessive shaft wear, and side pass inconsistency, particularly in the forming and sizing sections.

Challenge: 
A detailed evaluation revealed several mechanical issues that needed correction prior to alignment. Multiple bearing blocks and bearings were found to be loose, particularly in the breakdown passes and side pass stands. Shaft phasing problems were also detected — with several drive shafts visibly out of time, including the #7 Bottom and S4 Bottom positions — which can result in inconsistent RPM delivery to the tooling and dimensional variation in the finished tube.

The inspection also highlighted potential spacer issues and contamination risks in the bearing block assemblies. Improper arrangement of locking spacers and debris between end caps were possible causes of looseness. Some washers under side pass stands were visibly damaged from bearing failure and would need to be replaced. These issues, if left unresolved, would compromise any future alignment by introducing mechanical instability into the setup.

Solution: 
Technicians provided a clear action plan for repairs and pre-alignment preparation. This included verifying all bearings for rough rotation, re-preloading where necessary, and removing any adjustable alignment spacers to be replaced with solid “soft” spacers for precision alignment. Operators were also instructed to install side pass rolls and confirm roll parallelism using a straight edge. All outboard sleeves and missing snap rings were to be replaced or secured.

Additionally, the team recommended removing the leveler unit and Turks head base prior to the alignment to allow clean scope access. A full mill steam cleaning was also advised. With the corrective actions implemented, the mill would be fully prepared for optical alignment — resulting in long-term mechanical reliability and accurate tooling engagement.

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.