Pulp and Paper Canada

Features Maintenance & Reliability
Roll Armor coating eliminates maintenance headache for paper mill

Nov. 22, 2017 - The adage “work smarter, not harder” applies to all of us. If a simple improvement can save you time, money and resources, it’s well worth the initial investment.

November 22, 2017  By Robert Rourke

A large paper manufacturer in the Northeast experienced hazing issues on its coated hot calender rolls. Every time the mill ran a critical grade of paper with a demanding finish, the hazing decreased the quality of the product.

After each run, mill engineers had to stop production and clean roll surfaces, buffing and polishing rolls by hand. The process took about three hours. In total, the mill lost up to six hours production time per month between grade changes.

Producing better results
Unwilling to continue losing time and money, mill management called Precision Roll Grinders (PRG). PRG visited the customer at the mill, inspected the roll and analyzed issues with the product. The roll was sent to PRG and, not unlike a physician, the firm successfully diagnosed the problem and prescribed Roll Armor coating.


The diagnosis
• The coating on the roll had a higher-than-normal porosity. This accounted for the hazing issues.
• RA (Roughness Average) levels were high – 200 to 300 per cent above spec.
• Variations in the thermal spray coating on the roll face caused quality problems in the final product.
• The profile was out 1.7 thousandths of an inch front to back. Spec was 0.0002 inch.
• TIR was out 0.0003 inch on one side, and 0.0004 inch on the other.

The results
After a regrind to remove the old coating, and application of PRG’s Roll Armor, the roll was installed and exceeded management expectations. The proprietary coating created a dense, even and strong surface area that made grade changes simple. The project resulted in a range of benefits:

• Paper quality improved significantly.
• Time between grade changes decreased from three hours to half an hour, allowing the mill to run an additional five hours a month.
• The density of the Roll Armor coating helped eliminate variations in thermal spray coating thickness and TIR issues.
• Machinery ran at greater speeds.
• The mill saw a significant reduction in maintenance and downtime.
• Roll Armor significantly increased the life of the roll.
• Customers reported fewer print issues, better runnability, and most importantly, repeat orders.

The June 2017 Smithers Marketing Report, The Future of Specialty Papers to 2022, predicts “the global market for specialty papers is forecast to grow at an annual average rate of 2.2% over the next five years to 27.0 million tons by 2022.”

Paper mills that work smarter, not harder, understand the value improved coating provides. Your mill will not only produce a better quality, defect-free product, but also one made faster with less unplanned downtime. Is your mill prepared?

This article was originally published on the Precision Roll Grinders blog.

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