Permalin Manufacturing Co. (Holyoke, MA), a supplier to the book-binding industry, uses differential shafts during the slitter/rewinder process because differential shafts will allow for caliper variations and allow them to wind hard, narrow-width rolls to large diameters. Permalin sheets, trims, slits and embosses paper and cloth materials used in book-binding processes.

"Because the differential shafts compensate for the caliper variations, you don't lose cuts which add cost to production," says Bob Therrien, plant supervisor. Permalin has been using Tidland Corp.'s (www.tidland.com) Equalizer Model D2 differential shafts since 2001.

Since then, Tidland has made enhancements to the Equalizer series to allow precise control of tension as low as 0.15 pli. The latest version, the Model D4, is a two-row, 12-ball torque activated core-lock design that insures equalized tension and superior roll structure across any combination of roll widths, Tidland said.