Most brass sold for machining in the UK is CZ121, and most brass sold for machining in America is C360. They are close enough that if you have been handed a drawing calling up one and a bar rack containing the other, you can usually proceed.
That naming confusion is the single most common brass question we field, so this guide starts there before moving on to what actually changes your part price.
We turn brass components every week at our Leighton Buzzard facility, from electrical contacts to plumbing fittings, so the perspective here is what these grades do at the machine rather than what the datasheet says.
The Naming Problem
Brass grades carry three or four designations depending on which standard you are reading, and the same alloy appears under all of them.
| Alloy | British (BS) | European (EN) | American (UNS) | Japanese |
|---|---|---|---|---|
| Free-machining brass | CZ121 | CW614N | C36000 (C360) | C3604 |
| Hot stamping brass | CZ122 | CW617N | C37700 | C3771 |
| Cold working brass | CZ108 | CW508L | C27200 | C2720 |
| Cartridge brass | CZ106 | CW505L | C26000 (C260) | C2600 |
If your drawing says CZ121 and your stockholder offers CW614N, they are the same material. The European designations replaced the old CZ numbers in UK practice, but plenty of drawings still carry CZ, and both remain in everyday use.
The one to watch is the American set. C360 and CZ121 are not chemically identical, and the difference occasionally matters.
CZ121 vs C360
Both are leaded free-machining brasses rated at 100 on the machinability index. The index exists precisely because free-machining brass is the benchmark every other material is measured against.
The composition differs slightly. C360 typically runs 60 to 63% copper, while CZ121 sits nearer 57 to 59%, with the balance mostly zinc and around 2.5 to 3.5% lead in both.
For a machined part, that gap rarely changes anything. Higher copper content gives C360 marginally better corrosion resistance and slightly different hot working behaviour, which is why it occasionally appears on drawings for parts in aggressive environments.
Our practical advice: if a drawing specifies C360 and the part is machined from bar for a normal service environment, CZ121 will perform identically and is far easier to source in the UK. If the specification is contractual, ask before substituting.
The Grades That Actually Machine Well
Machinability ratings vary between published sources, but the ranking is consistent.
| Grade | Machinability | Best for | Notes |
|---|---|---|---|
| CZ121 / CW614N | 100 | Turned parts from bar | The benchmark. Highest speeds, cleanest chips |
| C360 / C36000 | 100 | US-specified turned parts | Slightly higher copper than CZ121 |
| CW617N / CZ122 | 70 to 80 | Hot stamped then machined | Common for forged valve bodies finished on a lathe |
| CW724R (ecobrass) | 70 to 85 | Lead-free machined parts | Silicon brass. Higher strength, higher cost |
| CZ108 / CW508L | 30 | Formed and bent parts | Made for cold working, not cutting |
| C260 cartridge brass | 30 | Deep drawn parts | Excellent formability, poor machinability |
The cliff between the free-machining grades and the forming grades is the important part of that table. CZ108 and C260 are not slightly harder to machine than CZ121, they are roughly three times harder, and specifying one for a turned part costs real money.
We see this most often on drawings inherited from a formed or pressed component that has since moved to machining. The material called up made sense for the old process and quietly triples cycle time on the new one.
Why Lead Makes the Difference
Lead is not alloyed into brass, it sits as fine particles distributed through the structure. Those particles do two jobs at the cutting edge.
They act as internal chip breakers, so chips snap into short curls instead of forming the long strings that tangle around tooling. And they lubricate the cut, reducing friction and letting the tool run faster and cooler.
The result is a material that cuts at very high spindle speeds, produces an excellent finish straight off the tool, and clears its own swarf. That combination is why brass turned parts remain economical at volumes where other materials become expensive.
Remove the lead and you lose both effects at once, which is the whole difficulty with lead-free brass.
What Lead-Free Brass Costs You
Lead-free and low-lead brasses exist because regulations restrict lead in drinking water systems and in electrical and electronic equipment under RoHS. In the UK, components for potable water need approval under schemes such as WRAS, and that approval will not be granted for a standard leaded brass.
The main replacements are silicon brasses such as CW724R, widely sold as ecobrass, and reduced-lead grades such as CW511L.
They work, and they machine acceptably. But expect three changes: machinability drops to roughly 70 to 85 against 100, so cycle times lengthen; the material costs more per kilogram; and chip control is less obliging, which matters most on automatic lathes running unattended.
Our advice is simple. Specify lead-free where the application genuinely requires it, which means potable water, food contact or RoHS-governed electronics, and use CZ121 everywhere else.
Specifying lead-free across an entire drawing pack because one part touches drinking water is a common and expensive habit.
Choosing a Grade in Three Questions
- Does the part contact drinking water, food or fall under RoHS? If yes, specify a lead-free grade such as CW724R and check the approval scheme it needs.
- Is the part machined from bar, or formed? Machined from bar means CZ121 or C360. Formed, drawn or heavily bent means CZ108 or C260.
- Is it hot stamped before machining? Then CW617N is the normal choice, and it finishes on a lathe perfectly well.
Everything else, including colour, corrosion resistance in normal environments and strength, tends to be a secondary consideration for typical turned components.
What Brass Costs to Machine
Brass rewards you twice: fast cycle times and long tool life. Against a stainless steel part of identical geometry, a CZ121 component will normally cost noticeably less to produce even though brass costs more per kilogram than steel.
That advantage grows with quantity. On a batch of several thousand turned parts, the difference in cycle time between CZ121 and a lead-free grade compounds into a meaningful sum.
The material price itself tracks the copper market, so brass moves with commodity pricing in a way that machining time does not. Our guide to CNC machining costs in the UK covers how material, cycle time and batch size combine into a quoted price.
For full published composition and property data across the brass family, the Copper Development Association maintains the reference datasheets.
Getting Brass Parts Machined
Send us the drawing with the grade and, if it matters, the compliance standard the part has to meet. If the specified grade looks wrong for how the part is actually made, we will say so at quotation rather than quietly machining an expensive material.
We machine CZ121, CZ108, C360, CW617N and lead-free grades to ±0.01mm, in batches from one to 10,000, with full material certification.