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June 09, 2006
What Wrap Angle for Tangential vs Wrap Shear Slitting?
Question:
For tangential v. wrap shear slitting systems, how much wrap can you have before you are no longer considered tangential shear?
Our "tangential" web machines have a very small amount of wrap (~1 degree). We are contemplating some new machine designs, and it got me wondering,
Is the need for better web support typically the largest factor for switching to a wrap system?
Thanks in advance,
Jason Nelson, Toray
JNelson@toraycompam.com
Reply:
I think I better drum up Reiny Schable to chime in on this one.
I think one of the main benefits of tangential shear is to drive the top and bottom knives at the speed to get the best cut. This may be a bottom knife that is slightly faster than the web. Tangential shear also the web and knife to slip without significant friction and web tensioning. The wrap on tangential slitting is often nearly equal to the angle included by the chord length of engagement, so you aren't pulling the web up against the top knife or off the bottom knife until it has passed the entire overlap length.
Per your question on web support... Web support can be important in both wrap and tangential slitting. For tangential, you can get away with large gaps between bottom knives, but that doesn't mean you shouldn't consider supporting the web between knives.
tjw
Posted by Tim Walker at June 9, 2006 09:36 AM
