Traction in web handling: A review
D. P. Jones · SHAREOK (University of Oklahoma; Oklahoma State University; Central Oklahoma University) · 2001
In web processes, at least one moving machine component must drive the material through a friction force at the interface. This force, or traction, inevitably falls as speed increases, and is accompanied by a degree of slip. As a result, traction often limits productivity through constraints on product output and quality. Although there are high traction elements available for web lines, such as nips, edge grippers and vacuum pull rollers; the majority of machines still rely on driven rollers wrapped by the web. Machinery manufacturers seek to optimise the design of the traction elements by specifying layout, drive and roller surfaces, whereas material manufacturers seek web surfaces that will perform well irrespective of machine. In other situations, low traction may be desirable. A roller imparts stability to the web if traction is high enough to ensure speed matching, or if the traction is low at all times so that roller has little influence on the web. It is important to avoid intermediate situations where intermittent slip occurs.