Surface Finish Calculator
Calculate theoretical Ra from feed and nose radius for turning; includes typical Ra values for common manufacturing processes
Surface Finish Calculator
Theoretical Ra for turning: Ra = f² / (32·r) where f = feed (mm/rev), r = nose radius (mm)
Theoretical Surface Roughness (Turning)
This is the ideal theoretical value. Actual Ra is typically 1.5–3× higher due to vibration, tool wear, and built-up edge.
Typical Ra by Manufacturing Process
| Process | Ra min (μm) | Ra max (μm) |
|---|---|---|
| Flame cutting | 12.5 | 50 |
| Sawing | 3.2 | 25 |
| Planing / Shaping | 0.8 | 25 |
| Drilling | 0.8 | 6.3 |
| Turning (rough) | 1.6 | 12.5 |
| Turning (finish) | 0.4 | 1.6 |
| Milling (peripheral) | 0.8 | 6.3 |
| Milling (end) | 0.4 | 3.2 |
| Reaming | 0.4 | 1.6 |
| Broaching | 0.4 | 1.6 |
| Cylindrical grinding | 0.1 | 1.6 |
| Surface grinding | 0.1 | 1.6 |
| Honing | 0.025 | 0.4 |
| Lapping | 0.006 | 0.1 |
| Superfinishing | 0.006 | 0.05 |
| Sand casting | 12.5 | 50 |
| Hot rolling | 1.6 | 25 |
| Cold rolling / Drawing | 0.1 | 1.6 |
| Die casting | 0.8 | 3.2 |
| Investment casting | 0.8 | 6.3 |
Typical ranges. Actual values depend on material, tooling, and machine condition.
How to Use This Calculator
Enter your input values
Fill in all required input fields for the Surface Finish Calculator. Most fields include unit selectors so you can work in your preferred unit system.
Review your inputs
Double-check that all values are correct and that you have selected the right units for each field. Incorrect units are the most common source of calculation errors.
Read the results
The Surface Finish Calculator instantly computes the output and displays results with units. All calculations happen in your browser — no loading time and no data sent to a server.
Formula Reference
Surface Finish Calculator Formula
See calculator inputs for the governing equation
Variables: All variables and their units are labeled in the calculator interface above.
When to Use This Calculator
- •Use the Surface Finish Calculator when solving homework or exam problems that require quick numerical verification of your hand calculations.
- •Use it during the design phase to rapidly iterate on parameters before running detailed finite element simulations.
- •Use it when reviewing a colleague's calculation or checking a vendor's data sheet for plausibility.
- •Use it to generate reference data for a technical report or presentation without manual computation.
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