Wrong speed = tool wear.
Wrong feed rate = noise, burns, scrap.
Recommended feed per tooth
| Tool diameter | Aluminum alloy (mm/tooth) | Steel (mm/tooth) | Stainless steel (mm/tooth) |
|---|---|---|---|
| 3 mm | 0.015–0.03 | 0.01–0.02 | 0.008–0.015 |
| 6 mm | 0.03–0.06 | 0.02–0.035 | 0.015–0.025 |
| 12 mm | 0.06–0.10 | 0.035–0.06 | 0.025–0.045 |
How to calculate cutting data
Example: Tool: 6 mm 2-flute carbide end mill Material: Aluminum Alloy Surface Cutting Speed (SFM): 300 Feed per tooth: 0.05 mm/tooth
1. Speed (RPM): Speed = (300 × 3.82) ÷ 6 = 1910
2. Feed rate: Feed rate = 1910 × 0.05 × 2 = 191 mm/min
Most computer-aided manufacturing (CAM) software will do this calculation automatically – but be sure to verify the results!
Feed speed adjustment for different machining processes
| Process | Adjustment method |
|---|---|
| roughing | Increase feed per tooth and reduce speed |
| finishing | Reduce the feed per tooth and increase the speed |
| Plunge milling | Reduce feed rate by 30–50% (full-tooth cutting) |
| Corner processing | Reduce feed rate or use trochoidal machining path |
| Small knives | Reduce the rotation speed and feed rate at the same time to avoid tool breakage |
End mill geometry and its impact
- Fewer teeth = better chip evacuation (for aluminum)
- More teeth = smoother surface (for finishing)
- The helix angle changes the chip direction and cutting pressure
- Use short tools whenever possible – this increases rigidity
Feed rate and cutting speed by material
| Material | Surface cutting speed (SFM) range | Precautions |
|---|---|---|
| 6061 aluminum alloy | 250–500 | Use 2-3 fluted tools and a small feed per tooth |
| 1018 Steel | 80–150 | Use coated tools and coolant |
| 304 stainless steel | 60–100 | Use high-pressure coolant and low-speed machining |
| brass | 200–400 | Dry cutting or air cooling, no stickiness |
| titanium alloy | 30–60 | Low surface cutting speed, can use higher feed rate |
| UHMW plastics | 300–800 | Use sharp tools, air-cooled or dry cutting |
Feed rate and cutting speed problem troubleshooting
| symptom | Possible causes | Workaround |
|---|---|---|
| Tool breakage | Feed rate is too high and cutting depth is inappropriate | Reduce cutting depth and check feed per tooth |
| surface burns | Too high speed, no coolant used | Reduce the speed and use spray cooling/flood cooling |
| Flutter | The tool is too long and the feed rate is inappropriate | Use shorter tools and adjust speed |
| Poor surface finish | Tool blunting, feed rate too low | Grind the tool to increase feed rate |
Advanced CNC Feed Rate and Cutting Speed Mastering Techniques
- Refer to the tool manufacturer’s data sheet for ideal parameters
- Initial parameters should be conservative, and the feed rate should be gradually increased based on the effective tool path
- When making deep cuts, try High Efficiency Milling (HEM)
- Stepover should be ≤ 50% of the tool diameter for a smoother surface finish
- Use the feedrate override function of computer-aided manufacturing (CAM) to test actual machining performance
