Although many tend to forget about them, the pressure roll is one of the most important elements in a single facer. Many look at them as a simple cylindrical ground roll.

It is a cylindrical ground roll that is designed to apply uniform pressure throughout the length of its body so medium and liner paper can be properly glued. In order to get this uniform pressure, rolls must be ground with certain crowning since flexion is produced as being subject to pressure by its journals.

What we mean by crowning is the difference between the diameters in the center and at the end of the body of the roll. It varies from brand to brand, some have positive and some have negative crowning, but most models manage values between 0.003" (0.0762mm) and 0.010" (0.254mm). The only way to obtain precision crowning required for pressure rolls is using a CNC cylindrical grinder.