I'm building a shearing and piercing die for a customer and I want to figure out the approximate force neccesary for this die. It's got four
3/8" piercing punches and one 6" wide shear blade. This is using 1/8" thick AL stock.So he's got a 20T press and I'm thinking we need a bigger press. So how do I figure out the tonnage needed for this die?
Bob
rbi4t5t@soft6home.7net
(remove the 4567 and it'll get to me)
Generally, cutting length times thickness times shear strength of the material will result in cutting force required.
3/8 dia x PI x 4 =2.356 >I'm building a shearing and piercing die for a customer and I want to
"V" notch, or an angle on the punches would drop the tonnage on those also.
Best, Steve
Thanks for the info. Of all the books I've read, not one has had a good formulae for figuring punching forces. Also thanks for the idea of using angled or rooftop shearing. I know this reduces shearing forces but I've never known how to calculate the forces.
Bob-
First thing an apprentice toolmaker learns is cutting/punching forces.
Periphery of hole x thickness x 25 = tons in steel
Use 17 for aluminium.
Your four 3/8" holes would need a shade over 10 tons.You didn`t say what width you were shearing. Other thing to bear in mind is that press tonnage is only fully developed a short distance from bottom dead centre and some presses will run happily full time at maximum rating and some makes will not.
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