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CALCULATORS / SHEET METAL, FORMING AND WIRE

Deep-drawing blank and draw-ratio screening calculator

Cylindrical cup blank from area conservation; no thinning/flange allowance.

sheet-metal-deep-draw.napkin / editable
✓ checks pass

SCENARIO COMPARISON

Compare the numbers.

This source describes an analytical model. Its quantities and checks are the view.

ScenarioblankDiametermmdrawRatio
86.60251.73205
74.83311.87083

All calculated quantities are listed with the inputs. Switch to Source to inspect the equations.

SCENARIOS / CALCULATED VALUESSAME SOURCE

Change an input to see the consequences.

supplied draw ratio limit1.73 ✓ passes

BASELINE INPUTS

CALCULATED

blankDiameter86.603 mm
drawRatio1.7321

Edits change the baseline source.

Calculated from your source · not saved
Baseline · Baseline
supplied draw ratio limit1.73 ✓ passes
alternative · alternative
supplied draw ratio limit1.87 ✓ passes

Illustrative first-order example. Checks are editable requirements, not design standards. The broader topic may require additional equations, data, and validation.

Formula and units

This example uses the following equations. Input names and units match the editable source above.

blank diameter
blankDiameter = sqrt(diameter^2+4*diameter*height) [mm]
draw ratio
drawRatio = blankDiameter/diameter

Original worked example

These are the baseline values in the downloadable source. Edits above let you test your own values.

Given

diameter
50 mm
height
25 mm
limiting ratio
2

Calculated

blank diameter
86.6025 mm
draw ratio
1.73205

Assumptions and limits

Cylindrical cup blank from area conservation; no thinning/flange allowance.

The requirement checks use the limits written in this example. Passing a check does not establish that the model covers every load, material behavior, or operating condition in a real design.

Download this .napkin example ↓

Take it further with your agent

Napkin keeps the inputs, equations, checks and assumptions together in one study. Your agent sets it up; you change the numbers.

Try with Claude ↗

codex 'Use Napkin (https://napkin.engineering/mcp, or the local Napkin plugin) to build a study: Deep-drawing blank and draw-ratio screening. Inputs: cup geometry; material; thinning assumption. Outputs: blank diameter; draw ratio. Model scope: Specified bend geometry and calibrated material/process factors. Read napkin_capabilities and the current snapshot. Ask me for the values that matter, label assumptions with units, author .napkin source, validate it and apply it with napkin_source using the current revision, then open the study. Add checks for the limits I supply. Keep unsupported analyses explicit.'

Claude needs the Napkin connector; Codex needs the Napkin plugin. Set up your agent ↗

The broader study

The topic brief below describes the broader scope. The worked example above states the particular calculation it implements.

  • Inputs: cup geometry, material, thinning assumption
  • Outputs: blank diameter, draw ratio
  • Modes: calculate, compare, sweep
  • Drawing: Flat pattern and forming sequence

EXECUTABLE WORKED EXAMPLE · FIRST-ORDER MODEL · CHECK THE SCOPE & ASSUMPTIONS

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