Tips

Webs must stay in traction with rollers to properly handle them through any converting process. The web handling principle states that a web will seek to be perpendicular to a roller in its' entry span to that roller. Proper web handling relies on this principle. If webs are not in traction with rollers; if they slide around rollers in the machine instead of rollers being positively, synchronously, driven by the web, this web handling principle does not apply. Without the web handling principle, webs can wander, wrinkle and potentially crease, causing undo waste during your process.

Often, low tension can cause webs to lose traction with idler rollers. There simply is not enough web tension to deliver enough friction between the webs surface and the roller face to turn idler rollers. Think of the web as one long conveyor belt, driving each idler roller with which it comes in contact. Now imagine that conveyor belt being so loose that instead of driving the rollers, it slides over the roller face. This is the potential effect of extremely low tensioned webs.

There are many factors that may be considered to design rollers to rotate with webs as they flow through a converting machine. One of these design possibilities is to manufacture rollers with light weight materials. Hollow wall, engineered shape aluminum extruded tubing exists, which may be machined and properly fitted for idler roller applications. Designing idler rollers with hollow wall tubing may decrease inertia by 10% - 30% when compared to standard, solid wall tubing. This makes idler rollers easier to turn in a low-tension applications. Lowering inertia and making rollers turn freer will allow webs under extremely low tension to stay in traction with idler rollers. This will, in turn provide the best possible condition for handling webs through converting processes more accurately with less defects.