Page 31 - MetalForming August 2010

DieProtection for
Lean
Manufacturing
By Drew Stevens
Error-proofing concepts for toolmakers and die designers
This new book from the Precision Metalforming Association is written by long-time die-sensor expert Drew Stevens, who shows readers step by step how to develop modern sensing technologies for the pressroom and apply them to a lean-manufacturing environment. “Slow stamping-press speeds and frequent die crashes are not acceptable,” writes Stevens, “and the manufacturers that choose to shift their thinking to new technologies will prevail in the world metalforming market.”
To learn how to protect investments by applying sensors in your metalforming operation and support your lean-manufacturing directives, order a copy of Stevens’ book today.
Call Marlene at 216-901-8800 x127 Online at www.pma.org and visit our Online Store
sure will equal the punching force divid- ed by the cross-sectional area (A) of the punch tip.
Ft = Fp/􏰂 (1/2d)2
If the punch has a spring elector pin, the cross-sectional area is reduced by the area of the hole in the punch face. The force on an ejector type punch, similar to that shown, is found by:
Ft = Fp/􏰂 (1/2d – 1/2d1)2
Punch tip performance is reported to be best when the maximum loads remain below 60 percent of the com- pressive strength of the punch body
Tool Steel
Compressive Strength (PSI)
60% Strength (PSI)
A2
305,000 @ 60 Rc
183,000
M2
375,000 @ 62 Rc
225,000
M4
425,000 @ 63 Rc
255,000
M4
455,000 @ 65 Rc
273,000
CPM 10V
400,000 @ 63 Rc
240,000
material. The table below contains com- pressive strength data for some com- mon tool steels and heat treatments. To minimize punch-tip breakage prob- lems, the punch tip (Ft) load should be less than the value shown in the 60 per- cent strength column.
Taking this engineering approach to punch selection eliminates guesswork and maximizes punch-tip strength economically. MF
MetalForming magazine and the Precision Metalforming Association announce its premium e-mail newsletter, Tool & Die Authority.
Read more of Peter Ulintz’s insights in Tool & Die Authority, an electronic-only publication delivered to the e-mail inbox of paid subscribers each and every month. It delivers hard-core tool and die knowl- edge and insight from experts like Peter Ulintz. Sign up at www.metalforming- magazine.com/toolanddie.
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