Shredder Cutting Area Calculation

[ramadhankd]

Hello everyone,

I'm trying to design a plastic shredder machine, but I'm stuck on how to determine the cutting area of my shredder. I've already made some research, and I think that the cutting area depends on the blade thickness and the plastic thickness. As for why the blade thickness is important, that is because the plastic (or scrap) will be cut into the size of the blade thickness. The plastic scrap must also have a dimension more than the blade thickness. If less, then the plastic (or scrap) will be “pushed away” instead of getting cut because It will receive no resistance force.

My reference for this determination of cutting area is based on ASTM D732 - Shear Punch Tool and this website https://www.engineersedge.com/sheet_metal_pierce.htm

Please kindly tell me whether or not this area calculation is accurate.

Thank you.

 

[jrmichler]

The cutting area is the actual area that is sheared. For example, this sketch shows a 1/4" blade cutting downward (into the monitor). The cut perimeter (as in the engineersedge equation) is 2" + 1/4" + 2" = 4.25". The thickness is two layers of plastic, which is about (just a wild guess) 0.020" if the plastic is 0.010" thick. The cut area is then 0.020" X 4.25" = 0.085 square inches. The resulting cut piece will be 4" long, folded in half, and 0.25" wide.

 

[ramadhankd]

Oh yeah, that should be It. Then the perimeter length (and thus the cutting area) will depend on the knife trajectory and the distance between each adjacent knife. Thanks for helping me clear this up.