- March 23, 2012, Timothy J. Walker
WebHandlersQuiz 16: Spreading - Name a spreader or anti-wrinkle roller that does NOT have a rubber surface?
Every roller has some anti-wrinkle benefit due to inducing machine direction curvature in the web, providing shape stiffening.
A concave roller can be machined out of any material, including aluminum or steel.
A hyper-crowned roller, where the diameter variations are several times greater than web strain, can induce spreading, similar to a D-shaped bar pushed into the web.
There are some segmented bowed rollers with a series of cylindrical metal segments mounted, shish kabob style, on a curved shaft, though most bowed rollers have rubber sleeves.
In some cases, a metal roller with raised chevron ridges will prevent wrinkles by allowing the web to pass over a roller with many minor non-damaging buckles instead of a major crease or break causing wrinkle.
Chevron ridge rollers pointing upstream can have a plowing and spreading effect if they are not turning (then technically not a roller), driven below web speed, or reverse driven.
More on this topic was covered in this archived Web Lines column:
Concave Rollers Pros & Cons July 2005
If you missed it, here are all 20 questions in my Web Handler's Quiz.