Fiber strands are deposited in layers during the paper forming process. The z-directional tensile strength (z ply, ply bond, ZDT) is the measure of the internal strength between paper layers. The force required to pull fibers apart perpendicular to the plane of the paper is critical during converting for printing, folding, transit, and consumer applications.

A brown and kraft paper mill partnered with Precision Roll Grinders to find a way to increase machine speed with improved z-directional tensile strength. Beyond increasing machine speed, improving ZDT also enhances paper quality and reduces premature roll wear. PRG ground the rolls with a focus on improved roll profile, concentricity, and roundness and with no deviations larger than 0.0002 inches. Upon installation of the precision ground rolls, the machine’s z-directional tensile strength increased by 10%. This increased z-direction strength allowed the mill to increase machine speed by 0.7 ton/hour, representing a $40,000 increase in annual production.

Contact your local Precision Roll Grinders account manager to learn how precision grinding can improve your sheet consistency and machine throughput.