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Filed under: Slitting, Cutting --- Reiny Schable @ 08:38 AM

To determine the cause of slitter blade wear, look for the tell-tale signature wear patterns on blades that will help you differentiate between blade-to-blade wear, and web-to-blade wear.

Once the distinctive patterns of wear are classified, the solutions will be easier to recognize and implement without resorting to "taking a stab in the dark"' or applying an unnecessarily costly solution to a relatively simple problem.

Continue reading"The causes of blade wear in slitters."

Filed under: Slitting, Cutting --- Tim Walker @ 08:00 AM

Contributed by Tim Walker -

Question:
Can shear slitting scratch a film web? Is there any relationship between slit and web speed?

The only shear slitting has problems with slitting-related scratches. The scratch is usually near the slit edge, created by the web traveling under or over the top or bottom knife in the overlap region. Too much overspeed will make these scratches worse. I don’t believe that line speed if important. Usually these scratches are eliminated by changing the knife geometry. I have heard of many shear slitting processes change the both shear knives, especially the top knife, to a wider design to avoid scratching.

Filed under: Slitting, Cutting --- Tim Walker @ 09:36 AM

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

Filed under: Slitting, Cutting --- Reiny Schable @ 02:45 PM

THE NIP MUST BE CLOSED. In the rotary shear process, materials are slit in the nip between two overlapping, hardened metal disks that create stress in the shear mode sufficient to sever the product.

Continue reading"The open nip is a major cause of poor slitting"

Filed under: Slitting, Cutting --- Reiny Schable @ 08:59 AM

To determine the cause of slitter blade wear, look for the tell-tale signature wear patterns on blades that will help you differentiate between blade-to-blade wear, and web-to-blade wear.

Once the distinctive patterns of wear are classified, the solutions will be easier to recognize and implement without resorting to "taking a stab in the dark"' or applying an unnecessarily costly solution to a relatively simple problem.

Continue reading"Determining the cause of slitter blade wear"