Bronze Feeds & Speeds Chart
Quick-look reference data for bronze milling across soft bearing bronzes, tougher phosphor bronzes, and aluminum bronze alloys. Best used as a shop-floor starting chart before you validate alloy family, coating, coolant, and cut geometry in the calculator.
Need Exact Bronze Milling Numbers?
Use this chart for a fast first pass. Then move to the copper-alloy calculator when alloy family, cutter geometry, coolant, or heat control need a setup-specific answer.
What This Chart Covers Best
First-pass SFM and chip-load ranges for bronze milling where the main question is whether the job behaves like a soft bearing alloy or a tough aluminum-bronze family.
Where It Needs Backup
Drilling, turning, and thin-wall bronze work need feed-per-rev logic. Aluminum bronze also needs closer heat and coolant review before release because it behaves much closer to a tough steel than a soft bearing bronze.
Best Next Links
Branch to the copper-alloy calculator, turning calculator, or drilling calculator when the cut moves beyond a quick milling reference.
Bearing Bronze (C932 / C936 / C863)
High-lead tin bronzes designed for bearings, bushings, and wear plates. Soft (60-80 BHN), machines like butter. C932 (SAE 660) is the most common — found in every bearing catalog.
| Operation | SFM (Carbide) | Chip Load (1/2" EM) | DOC (Roughing) |
|---|---|---|---|
| Roughing | 500 - 800 | 0.004" - 0.007" | 1.0D - 1.5D |
| Finishing | 700 - 1000 | 0.001" - 0.003" | 0.02" - 0.05" |
| Drilling | 150 - 300 | 0.005" - 0.010"/rev | — |
Phosphor Bronze (C510 / C521 / C544)
Spring-temper bronze used for electrical connectors, washers, and corrosion-resistant fasteners. Tougher than bearing bronze, produces longer chips. C510 (5% Sn) and C521 (8% Sn) are the main grades.
| Operation | SFM (Carbide) | Chip Load (1/2" EM) | DOC (Roughing) |
|---|---|---|---|
| Roughing | 300 - 500 | 0.003" - 0.005" | 0.5D - 1.0D |
| Finishing | 450 - 700 | 0.001" - 0.002" | 0.01" - 0.03" |
Aluminum Bronze (C954 / C955 / C630)
High-strength bronze for marine propellers, landing gear bushings, and valve seats. C954 (AMS 4640) is the aerospace standard. Hardness ranges from 160-210 BHN — treat like a tough steel, not a soft bronze.
| Alloy | Operation | SFM (Coated Carbide) | Chip Load (1/2" EM) |
|---|---|---|---|
| C954 | Roughing | 200 - 350 | 0.003" - 0.005" |
| C954 | Finishing | 300 - 500 | 0.001" - 0.002" |
| C630 | General | 250 - 400 | 0.002" - 0.004" |
Bronze is NOT One Material
The difference between bearing bronze (C932) and aluminum bronze (C954) is large enough that treating them as one "bronze" family will mislead setup decisions. This matters most on milling jobs where the cutter and coating are chosen for chip behavior.
- C932 (Bearing): Soft, free-machining. High SFM, big chip loads. 2-flute uncoated.
- C510 (Phosphor): Medium difficulty. Moderate SFM. 3-flute coated or uncoated.
- C954 (Aluminum): Tough material. Reduced SFM. 4-flute coated carbide. If the job is drilling or turning, move to the dedicated calculator instead of translating a milling chart.
Frequently Asked Questions
What SFM should I use for bronze?
For bronze milling, it depends heavily on the alloy family. Bearing bronze can start much higher than aluminum bronze, while phosphor bronze sits in the middle. Use this chart as the first-pass window, then validate the exact alloy and tool geometry in the copper-alloy calculator before release.
What is the difference between bearing bronze and aluminum bronze?
Bearing bronze (C932) is soft (60-80 BHN), lead-containing, and machines like butter. Aluminum bronze (C954) is hard (160-210 BHN), corrosion-resistant, and machines like a tough steel. They require completely different parameters.
What coating should I use for machining bronze?
Bearing bronze: uncoated polished carbide or ZrN. Phosphor bronze: TiN or uncoated. Aluminum bronze: AlTiN or TiAlN (same as steel). The harder the bronze, the more it benefits from heat-resistant coatings.
Should I use coolant when machining bronze?
It depends on the alloy and operation. Bearing bronze often runs fine with air blast, phosphor bronze usually benefits from coolant for chip evacuation, and aluminum bronze often needs a more deliberate coolant strategy because heat rises quickly. For drilling or turning, use the dedicated calculator instead of carrying over a milling assumption.