Understanding Speeds and Feeds Calculations
This calculator computes cutting speed (ft/min or m/min) and feed rate (in/min or mm/min) for CNC machining based on spindle speed, tool diameter, tool material, chip load, and number of flutes.
Cutting speed is the speed of the tool’s edge relative to the workpiece. Feed rate is the speed at which the tool advances through the material. Formulas: Cutting Speed = (RPM × Diameter × π) / 12 (ft/min) or / 1000 (m/min); Feed Rate = RPM × Chip Load × Flutes.
Example Speeds and Feeds
| Tool Material | RPM | Diameter | Flutes | Chip Load | Cutting Speed | Feed Rate | Scenario |
|---|---|---|---|---|---|---|---|
| HSS | 1000 | 0.5 in. | 2 | 0.005 in./tooth | 131 ft/min | 10 in/min | Milling aluminum |
| Carbide | 800 | 0.25 in. | 4 | 0.003 in./tooth | 52 ft/min | 9.6 in/min | Turning steel |
| Carbide | 1200 | 1.0 in. | 2 | 0.01 in./tooth | 314 ft/min | 24 in/min | Routing wood |
How to Use the Speeds and Feeds Calculator
- Select the unit system (imperial or metric).
- Enter the spindle speed (RPM), tool diameter, number of flutes, and chip load.
- Choose the tool material (HSS or carbide) to view suggested cutting speed ranges.
- Click "Calculate Speeds and Feeds" to view the results and suggested range.
Speeds and Feeds Comparison
Comparison of calculated cutting speed and feed rate against suggested cutting speed range.
Frequently Asked Questions
What are cutting speed and feed rate in CNC machining?
Cutting speed is the speed of the tool’s edge relative to the workpiece (ft/min or m/min). Feed rate is the speed at which the tool advances through the material (in/min or mm/min), affecting tool life and surface finish.
How do tool material and chip load affect machining?
Carbide tools allow higher speeds due to better heat resistance. Chip load determines material removal rate, impacting feed rate and machining efficiency.