KEVOS® MAKEOS · Fabrication
Deep Drawing Reduction Sequence
How many draws does this shell need, and what diameter should each draw produce?
Sequence of shell diameters in successive deep drawing operations from the blank diameter, a first-draw ratio and a redraw ratio (each the drawn diameter divided by the previous diameter), the number of draws needed to reach the final diameter, and the reduction percentage at each step.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Blank diameter | mm | Diameter of the flat blank (from a shell-blank calculation). |
| Final shell diameter | mm | Mean diameter of the finished shell. |
| First draw ratio (d₁ ÷ D) | Limiting first-draw ratio for the material, thickness ratio and die (from drawing data or trials). | |
| Redraw ratio (dₙ ÷ dₙ₋₁) | Limiting ratio for each redraw (usually larger than the first). |
Method and formulas
- d₁ = m₁ D; dₙ = m_r dₙ₋₁ until the final diameter is reached.
- Number of draws n = 1 + ⌈log(d ÷ m₁ D) ÷ log m_r⌉ when d < m₁ D.
- The last draw is set to the final diameter; reduction = 1 − ratio.
- Example: a 100 mm blank to a 30 mm shell needs 4 draws.
Limitations
- Ratios depend on material, thickness-to-diameter ratio, die radii and lubrication; use your tested limits.
- Annealing between draws may be needed for work-hardening materials.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Plan the number of operations for a deep-drawn shell
- Lay out punch diameters for a draw sequence
- Check whether a shell can be drawn in fewer operations
Who it is for
- Toolmakers
- Press shop engineers
- Manufacturing engineers
What you get
- Number of draws
- Diameter after each draw
- Reduction at each draw
Interpreting the result
- Spreading reductions evenly over the draws, rather than leaving a tiny last draw, reduces risk of tearing.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 1353–1359. Topic reference; no source tables or recommended settings are reproduced.
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