Enter extrusion inputs
Formula used
Extrusion ratio: R = A₀ / Aƒ
True strain: ε = ln(R)
Area reduction: Reduction % = (1 - Aƒ / A₀) × 100
Net product length: Lƒ = L₀ × R × Recovery
Estimated pressure model: P = σavg × (1 + m + ln(R)) × Kdie × Ktype ÷ η
Estimated force: F = P × A₀
A₀ is billet area, Aƒ is final area, L₀ is billet length, σavg is average flow stress, m is friction factor, K values are process multipliers, and η is efficiency as a decimal.
How to use this calculator
- Select the billet shape and enter its dimensions or custom area.
- Select the extrudate shape and enter the finished dimensions or custom area.
- Add billet length and recovery when you need a product length estimate.
- Enter average flow stress, friction factor, die angle factor, and efficiency.
- Choose the extrusion method to apply the matching process factor.
- Optionally enter ram capacity to check estimated force utilization.
- Press Calculate now and review the result block above the form.
- Use the export buttons to save a CSV or PDF of the results.
Example data table
| Case | Billet area (mm²) | Final area (mm²) | Ratio | True strain | Reduction (%) |
|---|---|---|---|---|---|
| Round bar to round rod | 7853.982 | 1256.637 | 6.250 | 1.833 | 84.000 |
| Rectangular billet to strip | 9600.000 | 1200.000 | 8.000 | 2.079 | 87.500 |
| Custom section to profile | 6500.000 | 900.000 | 7.222 | 1.977 | 86.154 |
FAQs
1. What does extrusion ratio tell me?
It compares billet cross-sectional area to final product area. Higher ratios indicate more severe area reduction, higher strain, and usually greater pressure and force demand.
2. Why is true strain included?
True strain, shown as ln(R), measures deformation intensity. It helps compare process severity across different product sizes, materials, and shop conditions.
3. Can I use custom areas instead of dimensions?
Yes. Custom area is helpful when sections are complex, hollow, or already modeled elsewhere. It lets you calculate ratio without recreating every feature here.
4. Is the pressure result exact?
No. It is an engineering estimate based on flow stress, friction, efficiency, die factor, and method factor. Validate against trials, supplier data, and press experience.
5. Why does ram capacity utilization matter?
It shows how much of the stated press capacity the estimated force would consume. This helps screen setups before deeper tooling or scheduling decisions.
6. What if the ratio is below one?
A value below one means the final area is larger than the starting area. That is not normal forward extrusion, so the pressure estimate becomes less meaningful.
7. Does billet length change the ratio?
No. Ratio depends only on cross-sectional areas. Billet length is used here to estimate final product length from volume continuity and recovery.
8. Should I use hot or cold flow stress?
Use an average flow stress that matches the actual extrusion temperature and strain-rate condition. A mismatched stress value can distort pressure and force estimates.