From reheat to downcoilers, quality is imperative during every stage of the steelmaking process. If any part of the process is weak, it can plague production and be detrimental to quality and the bottom line. Faced with the high frequency of maintenance-related issues and costs of its coiler pinch rolls, Wheeling-Pittsburgh Steel Corporation’s hot strip mill easily identified this area as a trouble spot.

Room for Improvement
As the last step in forming the steel to coils, the coiler pinch rolls are critical for achieving quality and proper shape. Although two sets were in place to enable the mill to run faster, the cast iron rolls in the coiler pinch roll position of both the mill’s downcoilers needed to be changed every one to two weeks due to excessive wear.

“With the problem existing for as long as it had, it was accepted as standard operating procedure,” says Ken Sharrer, sales manager for Timken industrial services group. “But when the problem was brought to our attention during a routine call, we knew we could remedy the situation in a quick and reliable way.”

Familiar with the application through past experiences, Timken had a design in mind with a special steel overlay to combat the chronic wear problem of the rolls. When it offered the mill an alternative roll that would provide about 200 to 300 percent improvement in the roll life, Wheeling-Pittsburgh was a bit skeptical of such a promise, but agreed to a trial of the proposed steel-clad rolls.

“We’ve had such a long history with Timken and know the type of quality product they deliver that we felt very comfortable acting on their recommendations,” says Richard Hritz, process manager, Wheeling-Pittsburgh 80-inch hot strip roll and bearing shop.

Saving Solutions
Within a few months, two sets of test rolls were in place. Dressed with Timken’s Mill Clad overlay, the rolls ran for 12 weeks before being removed for evaluation. After 12 weeks of operation, the rolls were checked for wear. The bottom rolls were worn just 0.034 in. and 0.050 in. while the top rolls showed no significant wear in 12 weeks. Compared to the previous wear of 0.1 in. and 0.12 in. in one to two weeks, the solution succeeded in providing the mill with advantages that extend from longer service life.

“Our customers need more than just products,” Sharrer says. “Sometimes they need a fresh approach to an existing problem that will provide a practical, cost-efficient and reliable solution. Our wide range of technologies and application experience positions us to do just that.”

Additional benefits to Wheeling Pitt include:

• Increased coiler up-time and increased strip quality – The rolls maintain shape longer.
• Reduced roll inventory – The quality and reliability of the new rolls has eliminated the need for additional sets of spares on site.
• Saved work hours – Replacing the cast iron rolls took two men about eight hours every one to two weeks. Now, they only need changed every 16 to 20 weeks.
• Reduced redressing time of the rolls – The roll shop spent nearly four days a week redressing the crown on the cast iron rolls. Now, the rolls are redressed every 16 to 20 weeks.

Now the rolls can be redressed after being worn to predetermined minimum diameters. The top rolls are 36 inches in diameter, and the wear minimum is 34 inches. The bottom rolls are 20 inches with a wear minimum of 19 inches. With the wear diminished, rolls now can last approximately 16 to 20 weeks before needing redressed and years before needing reoverlayed. At that time, they are reoverlayed at a significant savings versus buying new.

“We have our own fires to put out day in and day out,” Hritz adds. “We’ve never quantified the savings dollar for dollar, but when a provider helps us to improve our production, that gives us an edge. Having a partner who contributes in such a way is invaluable.”

Wheeling-Pittsburgh Steel Corporation, headquartered in Wheeling, W. Va., is an integrated steel company engaged in the making, processing and fabrication of steel and steel products. The company’s products include hot rolled and cold rolled sheet and coated products such as galvanized, pre-painted and tin mill sheet. The company also produces a variety of steel products including roll formed corrugated roofing, roof deck, floor deck, culvert, bridgeform and other products used primarily by the construction, highway and agricultural markets.

Wheeling-Pittsburgh Steel is owned by Esmark Incorporated, a vertically integrated steel producer and distributor. Esmark provides just-in-time delivery of value-added steel products to approximately 2,000 core customers in the midwestern United States.