Brass Material Grades
Brass is copper and zinc, and the ratio plus the additions decide everything: how well it machines, whether it can be formed or welded, and whether it survives in water. This is a reference for the grades we machine and what each one is actually for.
Brass grades we machine
C360 covers the majority of machined brass work. The rest exist because C360 is bad at something specific.
| Grade | Composition note | Best for | Machinability |
|---|---|---|---|
| C360 free-cutting brass | Copper-zinc with lead added | Fittings, valve bodies, instrument and electrical parts | The benchmark — the best of any metal |
| C260 cartridge brass | 70/30 copper-zinc | Deep-drawn and formed parts | Fair — ductile, strings rather than chips |
| C230 red brass | 85% copper | Decorative parts, plumbing fittings | Good; warmer colour than C360 |
| C280 muntz metal | 60/40 copper-zinc | Structural and marine sheet | Fair; stronger and harder than C260 |
| C464 naval brass | Tin added | Marine hardware, parts submerged long term | Good — resists dezincification |
| C932 bearing bronze | Copper-tin-lead | Bushings, bearings, wear surfaces | Good; runs against steel without galling |
| Lead-free brasses (C692xx and similar) | Bismuth or silicon replacing lead | Drinking water and food contact parts | Fair to good, varies by grade — specify if a standard applies |
Why C360 is the default, and when it is wrong
The lead in C360 is what makes it machine so well: it breaks chips into short pieces that clear the cut, which means high feeds, long tool life and an excellent surface straight off the tool. On a turned part in quantity, brass is often the cheapest metal to produce despite the stock price.
C360 is wrong in two situations. If the part is submerged in water for long periods, zinc can leach out of the alloy and leave a weakened porous structure — dezincification — and naval brass or bronze should be specified instead. If the part is for drinking water or food contact, lead content may be restricted by regulation and a lead-free grade is required. Both of those are specification decisions rather than machining ones, and we will raise them if the drawing looks like a candidate.
Brass is also soft enough to mark easily. Polished or decorative parts need separating and wrapping rather than being packed loose.
| At a glance | |
|---|---|
| Typical tolerance | ±0.002 mm (±0.0001 in) on machined features |
| Surface finish | Excellent straight from the tool |
| Corrosion | Good in air; watch dezincification in prolonged water contact |
| Standard finishes | Polish, brush, nickel or chrome plate, clear lacquer, tumble |
| Certificates | EN 10204 3.1 on request |
Three specification notes
Say if the part touches drinking water
Lead-free grades exist for exactly this and are not interchangeable with C360. If a standard applies, name it on the drawing.
Say if the part is submerged
Naval brass or bronze rather than C360, because of dezincification over time.
Decide whether it stays bright
Bare brass tarnishes. Lacquer or plating stops it, and that belongs on the order.
Finishes that work on brass grades
Brass is finished for appearance or to stop tarnishing rather than for corrosion protection.
Send the brass drawing
Send the drawing and the grade, or the drawing and a sentence about what the part has to survive. You get a price, a lead time, and an engineer’s note on anything that will fight the tolerances.