EN
C260 and C360 are the two brass alloys you will see most often on machining drawings. They look identical — same golden color, nearly the same density — but inside a CNC machine they behave like two completely different metals. Pick the wrong one and you either overpay for cycle time or end up with a part that cracks during forming.
The short answer: C360 (free-machining brass) is built for CNC cutting, while C260 (cartridge brass) is built for cold forming. C360 contains 2.5–3.7% lead, which makes it the machinability benchmark of the copper alloy family. C260 contains essentially no lead, which gives it outstanding ductility but makes it gummy on the cutting tool.
Below we break down the chemistry, mechanical properties, machining behavior, and cost implications of both grades — and how to decide which one belongs on your next drawing for brass CNC machining.
Both alloys are copper-zinc brasses, but their recipes differ in two important ways: C260 carries more copper (about 70%), while C360 trades some copper for a deliberate lead addition. That small amount of lead changes everything about how the metal behaves under a cutting tool.
| Element | C26000 (Cartridge Brass) | C36000 (Free-Machining Brass) |
|---|---|---|
| Copper (Cu) | 68.5 – 71.5% | 60.0 – 63.0% |
| Lead (Pb) | ≤ 0.07% (essentially lead-free) | 2.5 – 3.7% |
| Iron (Fe) | ≤ 0.05% | ≤ 0.35% |
| Zinc (Zn) | Remainder (~30%) | Remainder (~35%) |
On paper the two alloys are closer than most buyers expect. Strength is similar; the real gaps open up in ductility and machinability.
| Property | C26000 | C36000 |
|---|---|---|
| Tensile strength (annealed) | ≈ 325 MPa | ≈ 340 MPa |
| Elongation (H02 temper) | ≈ 23% — far more formable | ≈ 18% |
| Hardness (H02 temper) | ≈ HRB 70 | ≈ HRB 78 |
| Machinability rating | ≈ 30% | 100% (the industry benchmark) |
| Density | 8.53 g/cm³ | 8.50 g/cm³ |
The 2.5–3.7% lead in C360 is dispersed through the metal as microscopic particles. During cutting, those particles do two jobs at once: they act as a chip breaker, forcing the chip to snap into short, manageable segments, and as an internal lubricant, reducing friction between the tool and the workpiece.
The practical results on the shop floor:
C260 is not impossible to machine — with a 30% machinability rating it is still easier than stainless steel — but without lead it behaves in a "gummy" way. The material tends to stretch and tear rather than shear, producing long, continuous, stringy chips that tangle around tooling and demand constant coolant flushing.
If your design genuinely requires C260 (usually for its formability or its lead-free chemistry), an experienced shop compensates with:
Polished, razor-sharp carbide inserts with aggressive positive rake angles slice the metal cleanly instead of pushing it around, reducing built-up edge.
Dedicated chip-breaker insert geometries and interrupted cutting strategies (peck drilling, trochoidal milling) force the chip to break before it becomes a bird-nest.
Slower surface speeds with strong coolant flow control heat and flush chips away — which is exactly why a machined C260 part costs more than the same part in C360.
The decision rarely comes down to strength — it comes down to how the part is made and where it will be sold.
One compliance note: because of its lead content, standard C360 faces restrictions in EU electronics (RoHS) and in drinking-water systems. If your product falls under those rules but still needs heavy machining, ask your supplier about engineered lead-free alternatives such as silicon-brass alloys (e.g., C69300) rather than forcing C260 into a high-volume machining job.
Per kilogram, C260 and C360 bar stock are priced in the same ballpark — the raw material is rarely the deciding factor. The cost difference shows up on the machine. A part that takes 60 seconds to cycle in C360 might take two to three times longer in C260 once you account for reduced speeds, extra chip-clearing, and more frequent insert changes.
That is why specifying "brass" without a grade is risky. If your drawing simply says "Material: Brass," most shops will quote C360 by default — which is exactly what you want for a machined part, but a problem if the part later needs to be bent or must be lead-free. Always call out the full UNS grade (C26000 or C36000) on the drawing.
C260 and C360 are both excellent brasses — they are just excellent at different things. C260's lead-free, high-ductility chemistry makes it the champion of stamping and deep drawing. C360's lead addition makes it the undisputed king of the CNC shop, with 100% machinability, the lowest cycle cost, and the best achievable finishes.
At ANOK Precision Manufacturing, we machine both grades every week as part of our metal CNC machining service. Our engineers provide free DFM feedback on every quote — including whether your part is better suited to C260, C360, or a lead-free alternative — and our ISO 9001:2015-certified shop holds tolerances down to ±0.002 mm with surface finishes to Ra 0.2. Upload your drawing through our precision brass CNC machining services page and we will recommend the most cost-effective, compliant alloy for your application.
No — they are very close. In the annealed condition C260 runs about 325 MPa tensile strength versus roughly 340 MPa for C360. Both alloys can be strengthened substantially through cold work, so the temper you specify matters more than the grade when it comes to strength.
Yes. With about 30% of C360's machinability it is still easier to cut than stainless steel. It simply requires sharper positive-rake tooling, chip-breaker geometries, slower speeds, and generous coolant — which increases cycle time and cost. For light machining on an otherwise formed part, it is perfectly workable.
Generally no. With 2.5–3.7% lead it exceeds RoHS limits for most electronics and does not meet NSF/ANSI 61 for drinking water. For those applications, specify a lead-free grade such as C260 for formed parts or an engineered lead-free machining brass like C69300 for machined parts.
Write the full UNS designation: C36000 if the part is primarily machined and has no lead restrictions, C26000 if it must be formed or lead-free. Never write just "brass" — the grade determines your quote, your lead time, and whether the part can pass compliance checks in its end market.