BIZOMAT MAKEOS · Fabrication
Deep Drawing and Ironing Punch Force
What punch force does this drawing or ironing operation need?
Punch force for the first draw of a cylindrical shell, for a subsequent (redraw) operation from blank and punch diameters, and for ironing a drawn wall to a thinner gauge, by the handbook formulas, with the drawing ratio and press capacity check.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Operation | choice | Choose the operation. |
| Material thickness | mm | Material thickness entering the operation. |
| Ultimate tensile strength | MPa | Ultimate tensile strength of the sheet. |
| Mean shell diameter after the first draw | mm | Mean diameter of the shell after the first draw. |
| Punch diameter (redraw) | mm | Punch diameter for the redraw. |
| Blank diameter (redraw) | mm | Original blank diameter. |
| Outside diameter of the cup (ironing) | mm | Outside diameter of the cup being ironed. |
| Punch-to-die clearance after ironing | mm | Radial clearance between punch and die, i.e. the wall thickness after ironing. |
| Compressive strength (ironing) | MPa | Compressive strength of the work-hardened wall. |
| Press capacity | kN | Rated capacity of the press. |
What each input means
Open an input to see what it is, its units, the worked example and the common mistakes, with a small diagram.
What this means: Operation
- What it is
- The press operation being sized: the first draw from a flat blank, a later redraw to a smaller diameter, or ironing to thin the wall.
- Units and format
- Choose one of 3 options from the list: First draw; Subsequent draw; Ironing.
- Example
- The form opens with “First draw” selected as a worked example. Choose the option that matches your case.
What this means: Material thickness
- What it is
- The thickness of the sheet or wall entering the operation; for ironing, the wall thickness before it is thinned.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 50 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 1.5 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- The first-draw and redraw forces rise in proportion.
What this means: Ultimate tensile strength
- What it is
- The ultimate tensile strength of the sheet material, used for the first-draw and redraw forces.
- Units and format
- Enter a number in MPa: megapascals (1 MPa = 1 N/mm²). The form accepts 0.000001 MPa to 3000 MPa. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 350 MPa as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- The first-draw and redraw forces rise in proportion.
- Get it right
- Use the supplier’s certified value for the actual material and temper.
What this means: Mean shell diameter after the first draw
- What it is
- The mean diameter of the shell formed by the first draw, measured to the middle of the wall: outside diameter minus one thickness.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 10000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 80 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- The first-draw force rises in proportion.
What this means: Punch diameter (redraw)
- What it is
- The diameter of the punch for a subsequent draw, which sets the new inside diameter of the shell.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 10000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 60 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
What this means: Blank diameter (redraw)
- What it is
- The diameter of the original flat blank, compared with the redraw punch diameter in the subsequent-draw formula. It must be larger than the punch.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 10000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 120 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
What this means: Outside diameter of the cup (ironing)
- What it is
- The outside diameter of the drawn cup as it goes into the ironing die.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 10000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 62 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
What this means: Punch-to-die clearance after ironing
- What it is
- The radial gap between the ironing punch and die, which equals the wall thickness after ironing; it must be less than the incoming thickness.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 50 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 1.2 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- The ironing force falls as it approaches the incoming thickness, because the force depends on the thickness removed.
What this means: Compressive strength (ironing)
- What it is
- The compressive strength of the work-hardened wall material being ironed, used only for the ironing force.
- Units and format
- Enter a number in MPa: megapascals (1 MPa = 1 N/mm²). The form accepts 0.000001 MPa to 5000 MPa. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 400 MPa as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Take it from material test data for the drawn condition, not the annealed sheet.
What this means: Press capacity
- What it is
- The rated force capacity of the press that will do the operation; the punch force is compared with it.
- Units and format
- Enter a number in kN: kilonewtons (1 kN = 1000 N). The form accepts 0.000001 kN to 1000000 kN. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 250 kN as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Check that the rating applies at the point of the stroke where the peak force occurs.
Method and formulas
- First draw: F₁ = π d_m T × UTS.
- Subsequent draw: F = π d_p T × UTS × (D ÷ d_p − 0.7).
- Ironing: F = π d₀ (T − c) S_c.
- Example: a first draw at 80 mm mean diameter in 1.5 mm sheet needs about 131.95 kN.
Limitations
- Friction and blank-holder force are not included; allow a margin on the press rating.
- Drawing limits depend on the material and die radii; confirm with trials.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Choose a press for a drawn shell
- Estimate forces for each operation in a draw sequence
- Check whether ironing fits the available press
Who it is for
- Fabrication supervisors
- Manufacturing engineers
- Estimators
What you get
- Punch force
- Drawing ratio or wall reduction
- Press utilisation
Interpreting the result
- Keep peak force well within the press rating at the point in the stroke where it occurs.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 1353–1361. Topic reference; no source tables or recommended settings are reproduced.
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