Engineering tools

Wire Drawing Calculator — Guide

Single-pass check and full pass schedule — area reduction, true strain, draw stress, and annealing guidance for round wire drawing.

What this calculator does

Wire drawing reduces diameter (and increases length) by pulling wire through a die under tension. Each pass through a die is a discrete reduction step. This calculator handles two modes — checking a single pass for its reduction and stress, or building a complete multi-pass schedule from a starting stock diameter down to a finished size, with annealing points flagged where the cumulative cold work reaches the material's safe limit.

Round wire only: this calculator models round-to-round drawing through a die. For non-round sections (drawing or rolling to shaped profiles), see the Wire Profile Rolling Calculator which models the round-to-keystone section relationship.

Material selection

Selecting a material locks three fields to sensible starting values: annealed yield stress σ_y0, maximum safe area reduction per pass, and maximum cumulative true strain before annealing is recommended. Switch to Custom to enter your own values — useful if you have measured data for a specific wire batch.

These are representative values for medium wire sizes — they vary with wire diameter, temper and supplier. The max-reduction-per-pass and anneal-limit values in particular are conservative starting points; your actual process may tolerate more or less depending on die angle, lubrication, and wire condition.

Material	σ_y0 (MPa)	Max reduction/pass	Max cumulative strain
Mild Steel (low carbon)	280	22%	0.60
Medium Carbon Steel	380	20%	0.55
High Carbon / Spring Steel	700	16%	0.40
Stainless 304	290	18%	0.45
Stainless 316	310	18%	0.45
Copper (annealed)	70	30%	0.80
Brass (70/30)	100	28%	0.70
Aluminium (1xxx/3xxx)	35	30%	0.80

Friction / redundant work factor φ

The draw stress estimate uses a factor φ (phi) to account for friction at the die face and redundant deformation (internal shearing work that isn't purely productive elongation). The default is 1.20, which is a reasonable mid-range value for well-lubricated drawing. Increase it toward 1.5 for difficult conditions (high die angle, poor lubrication, hard material); decrease it toward 1.0 only for ideal, well-characterised conditions. This factor affects the stress estimate only — it doesn't change the area reduction, true strain, or annealing threshold calculations.

Single pass check

Enter the entry and exit diameters, plus any cumulative strain already applied to this wire since its last anneal. The calculator returns:

Output	Meaning
Area reduction	(A₀ − A₁)/A₀ — the fraction of cross-sectional area removed in this pass
True strain (this pass)	ε = 2·ln(d₀/d₁) — additive across passes since the last anneal
Draw stress vs strength	Estimated draw stress compared to the work-hardened exit yield strength, with a safety ratio. Below 1.4× is flagged as marginal.
Annealing status	Cumulative strain (prior + this pass) checked against the material's safe limit — flags if annealing is due.

Worked example — single pass

Mild steel, d₀ = 3.000mm → d₁ = 2.700mm, no prior strain, φ = 1.20

Result	Value
Area reduction	19.0%
True strain (this pass)	0.211
Estimated draw stress	~72 MPa
Exit yield strength	~291 MPa
Safety ratio	4.0× ✓ well within range
Cumulative strain	0.211 of 0.60 limit — OK, continue without annealing

Full pass schedule

Enter the starting stock diameter, finished diameter, and a target reduction per pass. The calculator builds a complete pass schedule, stepping down through each die until the finished size is reached. It automatically caps the per-pass reduction at the material's safe maximum if your target exceeds it, and flags which passes need an intermediate anneal before continuing.

The schedule table uses highlighted rows (orange background) to show passes after which annealing is recommended before proceeding to the next die. After each anneal, the cumulative strain counter resets.

Worked example — full schedule

Mild steel (σ_y0 = 280 MPa, max 22%/pass, max strain 0.60), stock d = 6.000mm → finished d = 2.000mm, target reduction 18%/pass

Pass	Entry Ø (mm)	Exit Ø (mm)	Reduction	Strain (pass)	Cum. strain	Status
1	6.000	5.433	18.0%	0.198	0.198	OK
2	5.433	4.920	18.0%	0.198	0.397	OK
3	4.920	4.455	18.0%	0.198	0.595	OK
4	4.455	4.034	18.0%	0.198	0.794	Anneal after this pass
5	4.034	3.653	18.0%	0.198	0.198	OK
6	3.653	3.308	18.0%	0.198	0.397	OK
7	3.308	2.996	18.0%	0.198	0.595	OK
8	2.996	2.713	18.0%	0.198	0.794	Anneal after this pass
9–11	2.713	2.014	18.0%	0.198 ea.	to 0.595	OK
12	2.014	2.000	1.4%	0.014	0.610	Anneal after this pass

12 passes total, 2 intermediate anneals required, 3rd anneal at finish. Total true strain 2.197.

Disclaimer

This calculator is provided free of charge and on an as-is basis, with no warranty or guarantee of accuracy, fitness for purpose, or suitability for any specific application.

Material limits (max reduction per pass, cumulative strain thresholds) are representative starting points for typical medium wire sizes drawn under good conditions. They are not guaranteed limits — actual process capability depends on die geometry, lubrication, wire condition, draw speed and equipment. Always validate a new schedule with trial passes before committing to production.

AbarTech Ltd accepts no liability for any loss, damage, scrap, wire breakage or other outcome arising from use of this tool.

If you'd like engineering support on a specific drawing schedule, get in touch.