HOW AND WHY FAST PIERCETM HIGH VELOCITY STAMPING WORKS
Utilizing High Strain Rate Technology
A conventional press cannot efficiently stamp many of the new high strength steel alloys and composites simply because they are harder and cause the tools to fail prematurely. Many companies try and overcome this by heating the material, or stamping it soft and sending it to heat treating.
For decades there have been numerous studies to determine what cutting at different rates does to the material.
One famous study, the Charpy Impact Test, has concluded that at higher strain rates it takes substantially less energy to cut hard materials due to their ductile/brittle transition properties. Applying the load at a high rate rapidly increases the temperature in the cutting zone and makes it easier to cut.
We found that that when increasing the punch velocity, the measured forces on the punches decreased by as much as 60%. The reduction in energy required directly reduces the amount of force that the punch and die endure, thus increasing tool life dramatically!
Reduced roll over and work hardening also attributed to less force and wear on the tool.
WHY PART QUALITY IMPROVES WHEN USING THE NEW FAST PIERCE METAL STAMPING PRESS
Rollover and flatness problems are caused by the work hardening effect that occurs before the punch penetration begins. The penetration force is much higher, thus causing the rollover and flatness distortions in the material. High velocity piercing dramatically reduces the material penetration forces, resulting almost no rollover or flatness distortions. When this occurs the process may be considered adiabatic.
RESULTS USING A CONVENTIONAL PRESS
Poor edge quality results because the shearing forces
exceed the break through rupture force thus the very
rough rupture zone. Fast Pierce stamping reduces the
shearing forces, preventing the rupture.
RESULTS USING A FAST PIERCETM PRESS
Spring back results because of complicated stress/strain relationships that occur when bending metals. When bends occur rapidly, as they do when using a fast pierce press, the temperature rise is increased dramatically. This equalizes the inner and outer surface temperatures, there by reducing the spring back.
Less oil required: Forces, friction and the punch dwell time are dramatically reduced when high velocity fast pierce presses are used. Therefore lubricants may be eliminated or changed to a light evaporating lubrication is often used. This, combined with the reduced burr, can eliminate many secondary part operations