What is the best type of grooving for my rollers?

David Roisum, Ph.D., Consulting Technical Editor -- Converting Magazine, 6/1/2006

This is a great question. However, it can't be answered precisely for many reasons. First, there are many web types; some of which can't handle narrow grooves (fouling) and others that can't handle wide grooves (wrinkling). Second, there are several reasons to groove: including handling air entrainment on an idler roller, burping air in a wound roll against a nip roller, traction and so on.

Motivations for grooving do not, however, include spreading with spiral grooves, despite the widespread belief to the contrary. In any case, the main reason we can't always give good answers is that we simply don't know. There has been almost zero research on the subject. Thus, much of the practice in the industry is just someone's best guess. Hopefully this has been an educated guess, based on trying several things and closely observing the results.

Perhaps the best illustration of grooving patterns comes from the former Beloit Corp., which was once one of the largest paper machine builders in the world. There were more than 2,000 different grooving patterns that had been used at one time or another—the majority for water removal on the wet end. Almost all applications will be well served by a few variations of the following options. Here are the most common grooving patterns and some typical applications.

Plain surface

The most common surface for low-speed applications is "as finished"
Also common in narrow-web converting

Roughened

Tungsten carbide plasma-flame coating, shot peening, knurling, etc.
Used for air handling on idler rollers
Used for traction on drive rollers against deformable or rough webs

Venta-groove

About 1/8 in. wide by 1/8 in. deep on ½-in. pitch, annular or single-lead spiral
Most common in paper, common in converting
Great air handling
May cause wrinkling on very thin grades

Cross hatch or diamond