Deep Drawing Force & LDR Calculator
Deep Drawing Force & LDR Calculator
Enter the material and geometry to get the maximum draw ratio, estimated drawing force, and safe wall-thinning limit — based on AUNOV measured LDR data, not generic ranges.
Draw ratio β = D₀/dₚ
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Safe max draw ratio (LDR−0.10)
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Est. drawing force F
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Max wall thinning / draw
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Formula (Siebel simplified): F ≈ π·dₚ·t·σ_UTS·(1+μ/α)·ln(D₀/dₚ), with α≈1 (90° die). Illustrative — confirm with DFM. AUNOV presses 5–500T, depth ≤150mm, tolerance ±0.05mm (ironing ±0.02mm).
AUNOV measured limiting draw ratio (LDR)
| Material | Measured LDR | Note |
|---|---|---|
| DC04 | 2.1–2.2 | Low-carbon steel |
| 304 | 1.85–2.05 | Stainless steel |
| 5052 | 1.80–1.95 | 5xxx aluminium, deep-drawable; 6xxx shallow only / T6 after forming |
Balford publishes generic 304 LDR ≈1.6–1.8 and low-carbon ≈1.8–2.0. AUNOV’s measured window is wider on the high side — that headroom is what lets us draw deeper in one stroke.
Frequently asked questions
How do I calculate deep drawing force for a cylindrical cup?
Use F ≈ π·dₚ·t·σ_UTS·(1+μ/α)·ln(D₀/dₚ). The dominant terms are punch diameter, thickness and material strength — so the same cup in 304 needs more tonnage than in DC04.
What is the maximum draw ratio for 304 stainless steel?
AUNOV measures 304 LDR at 1.85–2.05. Subtract ~0.10 for a safe production margin, so design first draws around β ≈ 1.8.
How much wall thinning is acceptable in deep drawing?
Keep single-draw thinning below (1 − 1/LDR)·100%. For 304 that is roughly 46–51%; in practice stay well under it and verify at the quote stage.
Can deep drawing replace machining for a hollow part?
Often yes — for axisymmetric housings, deep drawing cuts material waste and cycle time versus machining, at the cost of higher upfront tooling. AUNOV validates LDR on sample blanks before cutting a die.
Standards Behind the Numbers
The formulas and limits in our tools are anchored to the material properties measured by the standards below. We validate each tool result against a trial draw on the real material.
- ASTM E646 — Standard Test Method for Tensile Strain-Hardening Exponents (n) of Metallic Sheet Materials. The n-value sets how much a wall can thin before necking.
- ASTM E517 — Standard Test Method for Plastic Strain Ratio (r) of Sheet Metal. The r-value predicts earing in drawn cups.
- DIN 8584 — Manufacturing processes, forming: classification of deep drawing operations and their subgroups.
- ISO 20482 — Metallic materials: Erichsen cupping test, a formability measure complementary to LDR.
- Wikipedia: Anisotropy — explains the r-value and why earing directions form.