Feed and Speed Calculator for Aluminium: Chip Load Chart & RPM
On a desktop router, aluminium is limited by the machine long before it is limited by the chart. The published chip loads are achievable; holding the cutter rigidly enough to use them usually is not.
For aluminium, the recommended chip load runs from 0.051–0.076 mm per tooth on a 1/8″ cutter to 0.152–0.229 mm on a 1/2″. Typical spindle speeds sit between 10,000 and 18,000 RPM.
Your chip load is 0.1270 mm per tooth, which is within the recommended 0.102–0.152 mm range for aluminium with a 6.35 mm upcut spiral.
Aluminium. On a desktop router aluminium is limited by machine rigidity long before it is limited by the chart. Take shallow passes, keep the chip load up, and use a lubricant - dry cutting builds up on the flutes and snaps the tool.
Upcut spiral. The baseline the published charts assume. Chips are lifted clear of the cut, which keeps heat out of the workpiece at the cost of tear-out on the top surface.
How to cut aluminium on a CNC router → - the full how-to: which bit, workholding, chip evacuation and reading the cut.
How aluminium fails when the chip load is wrong
Two failures dominate. Built-up edge - aluminium welding itself to the flutes - turns a sharp cutter blunt in seconds and then snaps it. And chatter, the audible sign that the gantry is deflecting under load rather than the cutter removing material.
Setting up a cut in aluminium
Shallow passes and a maintained chip load, rather than deep passes at a timid feed, is the combination that works. Keep the chip load up even as you reduce depth: a thin chip in aluminium is what causes built-up edge in the first place. Use a lubricant - even a mist or a wax stick - because dry cutting is what welds the material to the tool.
The thing most people get wrong
6061 and 7075 machine well; 2024 and cast alloys are gummier and less predictable. And unless a manufacturer explicitly states a machine handles aluminium, treat 'cuts soft metal' in marketing copy as untested - it is exactly the kind of claim we score only when the maker publishes it.
Chip-load reference for aluminium
Recommended chip load per tooth by cutter diameter, before any adjustment for depth of cut or bit geometry. Values between the 1/8″, 1/4″ and 1/2″ anchors are interpolated.
| Cutter diameter | Chip load (mm/tooth) | Chip load (in/tooth) |
|---|---|---|
| 1/16" (1.59 mm) | 0.051 – 0.076 | 0.0020 – 0.0030 |
| 1/8" (3.18 mm) | 0.051 – 0.076 | 0.0020 – 0.0030 |
| 4 mm | 0.064 – 0.096 | 0.0025 – 0.0038 |
| 6 mm | 0.096 – 0.144 | 0.0038 – 0.0057 |
| 1/4" (6.35 mm) | 0.102 – 0.152 | 0.0040 – 0.0060 |
| 8 mm | 0.115 – 0.172 | 0.0045 – 0.0068 |
| 3/8" (9.53 mm) | 0.127 – 0.191 | 0.0050 – 0.0075 |
| 1/2" (12.70 mm) | 0.152 – 0.229 | 0.0060 – 0.0090 |
These are estimates derived from published tooling-manufacturer data, not test results. Always prove a new setting on scrap first. Sources are listed on the methodology page.
Other materials
Already running a feed rate and want to know what chip load it produces? Use the chip load calculator.