How Much Press Does Your Blank Take?
Pick a shape, its gauge and the steel grade, and see the force it takes to cut the blank and the size of press to run it on.
How It's Calculated
- Cut length
- the blank's outline, plus π × hole diameter for each hole
- Shear strength
- 0.8 × tensile strength
- Force, tons
- cut length × gauge × shear strength × blanks per stroke ÷ 2,000
- Force, kilonewtons
- tons × 8.896
- Press
- force × (1 + margin)
Related: What Happens Inside a Die · Automotive · Blanking
Questions About Press Tonnage
How do you calculate blanking tonnage?
Multiply the length of every edge the die cuts by the steel's thickness to get the area being sheared, then by the steel's shear strength. Divide pounds by 2,000 for tons. A 16 in circle in 0.105 in mild steel is about 50 in of cut, so roughly 50 × 0.105 × 48,000 ÷ 2,000, or 127 tons.
Can I use my own part drawing?
Yes. Choose From a DXF File under Shape and pick the file. It is read on your computer, not uploaded: the outline and holes are found, and lines on border, title block, dimension and note layers are left out. If the numbers look right, Quote These Numbers attaches the same file to your quote request. Use a flat pattern, not a formed part, and check the drawing above matches your part.
Why does steel grade matter so much?
Force rises in step with strength. The same blank in a 980 MPa advanced high-strength steel takes well over twice the force of mild steel, which can move a job to a bigger press and changes how the die must be built.
Why add a margin?
The calculated force is what it takes to shear sharp, well-set tooling through steel at its typical strength. Stripping the blank off the punch, dulling edges, and coils at the strong end of their range all add to it. Presses are also not meant to run at their full rating all day.
Do holes pierced in the same stroke count?
Yes. Every edge cut in one stroke adds to the force, so holes pierced at the same time as the blank add their own cut length. Several blanks per stroke multiply it.