Yoder Mill Line – Addressing Component Wear and Structural Instability

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: 
A field service inspection was performed on a Yoder mill line after operators reported recurring weld quality issues and evidence of edge damage on processed strip. The team suspected component wear or misalignment as the root cause. The client requested a full mechanical evaluation to identify potential sources of product variation and mechanical failure, particularly those affecting weld integrity.

Challenge: 
Upon inspection, several areas were identified as contributors to the ongoing problems. Some entry guide rolls had worn throat surfaces where the strip rides, affecting camber control and threatening to damage the material’s edges. The edge trim station was equipped with a minimal number of knives, which frequently overloaded the tooling and caused gouging on the strip during trimming operations. Driven shafts across the mill were measured for outer diameter wear; multiple shafts were found at or below the undersize threshold, leading to loose fit between the shaft’s O.D. and the tooling’s I.D. Additionally, the inboard bearing blocks exhibited endplay due to a fixed-radius design, making it difficult to hold consistent shaft position — especially critical for laser-welded products.

Another concern was the lubrication system. Greasing the inboard bearing blocks while the mill was running posed safety risks and often failed to ensure even grease distribution. The end caps lacked grease reliefs, increasing the chance of blowouts or dry bearings.

Solution: 
A comprehensive series of corrective recommendations was provided. The edge trim unit was specified for upgrade to a six-knife system — three per side — a configuration more in line with industry best practices for stainless applications. Worn driven shafts were recommended for hard surface chroming to not only restore their diameter but significantly increase lifespan and reduce roll seizure. For shaft wear mitigation in the interim, a film of Slick 50 lubricant was advised during tooling changes.

The fixed-radius bearing blocks were flagged for retrofit with adjustable Gibbs or conversion to a sandwich-block design with end caps, both aimed at eliminating endplay. This modification was especially important given the customer’s laser welding operation, where even minor shaft motion can compromise weld alignment.

To modernize the lubrication system, the technician recommended sealed end caps with relocated grease fittings and McMaster-Carr grease reliefs (part #1093K1). Remote grease lines were also suggested, allowing for safe and effective greasing while the mill was running — helping maintain consistent lubrication across all bearings.

These improvements, once implemented, would directly support better camber control, longer component life, safer maintenance routines, and — most importantly — more consistent weld quality.

Contact Roll-Kraft for a Tube & Pipe Mill Evaluation
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