Chip load is the thickness of material each flute removes, measured in inches per tooth. It is the foundation of any feed rate: once you know chip load, flute count, and RPM, the feed follows. Use these as conservative starting points and tune by chip color, sound, and finish.
Feed rate (IPM) = RPM × chip load × number of flutes. Run the numbers in the Feeds & Speeds calculators.
Chip load by tool diameter and material (in/tooth)
| Diameter | Aluminum | Brass | Mild steel | Stainless | Titanium | Plastic |
|---|---|---|---|---|---|---|
| 1/8 in | 0.0010 – 0.0020 | 0.0008 – 0.0015 | 0.0005 – 0.0010 | 0.0004 – 0.0008 | 0.0003 – 0.0006 | 0.0010 – 0.0020 |
| 1/4 in | 0.0020 – 0.0040 | 0.0015 – 0.0030 | 0.0010 – 0.0020 | 0.0008 – 0.0015 | 0.0006 – 0.0012 | 0.0020 – 0.0040 |
| 3/8 in | 0.0030 – 0.0050 | 0.0025 – 0.0040 | 0.0015 – 0.0030 | 0.0012 – 0.0020 | 0.0010 – 0.0018 | 0.0030 – 0.0050 |
| 1/2 in | 0.0040 – 0.0060 | 0.0030 – 0.0050 | 0.0020 – 0.0040 | 0.0015 – 0.0030 | 0.0012 – 0.0025 | 0.0040 – 0.0070 |
| 3/4 in | 0.0050 – 0.0080 | 0.0040 – 0.0065 | 0.0030 – 0.0050 | 0.0020 – 0.0035 | 0.0018 – 0.0030 | 0.0050 – 0.0090 |
| 1 in | 0.0060 – 0.0100 | 0.0050 – 0.0080 | 0.0040 – 0.0060 | 0.0025 – 0.0040 | 0.0022 – 0.0035 | 0.0060 – 0.0110 |
Carbide end mills, general milling. Defer to your tooling manufacturer and reduce for deep slots, long stickout, or flimsy setups.
Adjusting from the baseline
- Roughing can push to the high end of the range; finishing stays low for a clean surface.
- Light radial engagement (under about 1/3 of diameter) causes chip thinning — you can and should raise the programmed chip load to keep the real one in range.
- Deep axial cuts or long tools flex more, so drop the chip load to stay below the tool deflection limit.
- Tough or work-hardening alloys need a real chip, not a skim — too light rubs and hardens the surface.
See the full Feeds and Speeds Chart for matching cutting speeds.