Blank Size Calculator

This calculator uses the basic surface-area-conservation formula for blank diameter, which depends only on Part Diameter, Part Depth, and Flange Width. More detailed deep-drawing references add a small corner-radius correction term to the base formula, but that correction is a second-order effect next to diameter and depth and its coefficient varies by source, so this tool keeps Corner Radius as a reference input for die design without folding it into the blank size calculation.

A Drawing Ratio (blank diameter divided by part diameter) above roughly 2.0 to 2.2 means the material can't be drawn from a flat blank into the finished cup in a single press stroke without wrinkling the flange or tearing the cup wall, so the calculator's Number of Draws Needed output estimates how many progressive draw stages, each incrementally reducing diameter, the part will require. The same ratio also drives Est. Wall Thinning, a rough heuristic equal to (Drawing Ratio − 1) × 15%, capped at 40% -- higher ratios mean a more aggressive draw and thus more sidewall thinning, but treat this as a directional flag rather than a precise strain-analysis figure.

Flange Width adds an annular ring of material around the part's rim, and the calculator folds this in by computing an effective flange diameter and adding the area difference between the flanged and unflanged circles to the base blank-diameter formula. A wider flange increases Blank Diameter because more material must be reserved for that rim before the part is drawn.

Yes -- across this calculator's full input range, deeper parts always require a larger blank, because more material is needed to form the taller cylindrical wall. Blank Diameter grows with the square root of depth's contribution rather than linearly, so doubling Part Depth does not simply double the resulting Blank Diameter.

It's a solid first-pass estimate, not a final die dimension. Production blank sizing also folds in the material's specific anisotropy (r-value), friction and lubrication conditions, springback, and shop-specific trim practice, all of which shift the final blank size by a few percent from this simplified geometric calculation -- treat this output as a tryout starting point, not a number to cut hardened tooling to without a trial draw.