Machined Brass and Copper Parts for Electrical and Conductive Work
Shenzhen XS Precision machines brass and copper on the same multi-axis and Swiss-type equipment we run for stainless, with the tooling and the speeds these two metals actually need. Free-cutting brass comes off the machine almost without drama. Pure copper is a different job: soft, ductile and prone to built-up edge, so it is quoted and cut differently.
Brass and copper bar, sawn and tagged before it reaches a machine
Bar and hex stock to ASTM B16, B453, B187 and B371, with the heat number recorded against the bar the part was cut from. The two alloy families are stored and sawn separately so brass and copper never mix in the swarf bin.
Brass breaks its chips; copper wraps them around the tool
Brass and copper sit next to each other on the conductivity table and nothing else about them is similar on a lathe. Brass is a zinc alloy that shears cleanly. Copper is a soft, ductile metal that stretches before it separates. That one difference sets the tool geometry, the coolant policy and the price of the part.
Excellent conductivity, Good machinability and Wear resistance, by the numbers
Three numbers decide most brass and copper drawings: how well the alloy carries current, how fast it can be cut, and how it behaves where two surfaces slide against each other.
The trade-off is always conductivity against strength. Cold work raises the strength of copper and pulls conductivity down by a few percent. Beryllium copper C17200 offers around 22% IACS with four to five times the strength of pure copper, and CuCrZr sits between the two. Shenzhen XS Precision will say when the extra alloy is doing real work and when it is being paid for with no benefit.
Six alloys cover almost every brass and copper drawing
The copper-to-zinc ratio, and whether lead, tin, silicon or tellurium is present, decides machinability, strength, colour and whether the part is allowed near drinking water.
Specifying C36000 is the cheapest route to a machined brass part and the fastest route into a compliance problem: 3% lead sits inside the RoHS exemption for copper alloys, not outside the regulation. Where the part touches drinking water, is sold in California, or can reach a child, the drawing should name a lead-free grade and the order should carry the certificate.
Speeds that use the material instead of fighting it
Brass chips break into short commas while copper swarf comes off as a tangled ribbon
The chip is the cheapest quality indicator there is. Short sixes and nines out of brass mean the feed is right. A copper ribbon that wraps the tool means the feed is too light and the edge is rubbing — add feed rather than speed, and break the chip with a grooved insert.
Brass and copper swarf is clean, single-material and worth money. XS Precision keeps it in separate bins from steel and aluminium, because mixed swarf is sold as mixed swarf. On a family of parts that runs for years, that recovery is part of the price.
Electrical components, Precision fittings and Conductive parts
Almost every drawing we quote falls into one of three families, and each one is judged on a different measurement: contact resistance, sealing and thread quality, or bulk conductivity.
Plating is what turns a brass part into an electrical contact
Untreated brass tarnishes. On a connector that is not a cosmetic problem: the oxide and sulfide film that forms within weeks is an insulator, and contact resistance climbs with it. The finish exists to keep the surface metal the metal you specified.
Tin and nickel plated brass parts, one cut through to show the plating layers
Where plating is unwanted: benzotriazole passivation gives a thin anti-tarnish film that does not change dimensions, and a clear lacquer covers decorative hardware. Silver tarnishes in sulfur-bearing air, so a silver-plated contact either gets a barrier layer or a sealed environment.
Three failure modes are behind most brass and copper returns
One more failure has nothing to do with the alloy and everything to do with the assembly. Copper and brass are cathodic to steel, aluminium and zinc, so in a wet joint the other metal is the one that corrodes — sometimes badly. Aluminium bolted to brass in humid air is a known combination, and it is solved with an insulating washer, a plated fastener, or a change of one side of the joint.
The 4% lead exemption has a date and a condition on it
Lead is what makes free-cutting brass free-cutting, so compliance is not a paperwork afterthought on these parts. The rules moved in November 2025 and the dates below are the ones to design against.
Tight tolerances are routine on brass; the thermometer decides the last digit
Thermal expansion sets the floor on what a number means. Brass C36000 moves about 20.5 µm per metre per kelvin and copper about 17, so a 100 mm part grows roughly 0.02 mm over a 10 °C change. That is twice the ±0.01 mm band, which is why XS Precision states the temperature the report was taken at instead of just quoting the number.
A brass fitting measured on a granite plate during inspection, certificate alongside
Every order ships with a mill certificate to EN 10204 3.1 carrying the heat number, matched to the bar the part was cut from. Positive material identification by XRF separates C36000 from a lead-free grade on the shop floor, which is the mistake that actually happens when two alloys look identical in the rack.
Typical profile on brass: mill certificate, chemical composition, hardness, dimensional report at a stated temperature, plating thickness and, where the drawing calls for it, the ammonia vapour test for residual stress.
The bar is expensive; the cutting is cheap
Swarf is where some of it comes back. Brass and copper chips are clean, single-material and recyclable at a real discount to bar price, which is why brass, copper, aluminium and steel are bagged separately instead of being swept into one bin. On a part that runs for years, that recovery quietly pays for a percentage of the material.
The other lever is the one drawings forget: bar diameter. Brass is bought by weight, and a part designed around a standard bar size — 20 mm, 25 mm, 30 mm, 45 mm — removes both the material and the handling time that a special size adds. Shenzhen XS Precision will quote the standard-bar version next to the drawing version when the difference is worth having.
Four cases where another material is the better answer
Brass and copper questions, answered before the quote
Which brass should I specify for a machined fitting?
C36000 if lead is allowed on that part and nothing restricts it: it is the fastest and cheapest brass to machine. If the fitting touches drinking water, is sold in California, or can reach a child, specify a lead-free grade such as C69300 or CW724R and confirm the dezincification qualification for that exact grade rather than assuming it.
Is brass conductive enough to carry the current?
C36000 is about 26% IACS, which is fine for a terminal body, a pin or a housing and not fine for a current path. The current path is copper: C11000 ETP at 100% IACS and 58 MS/m, or tellurium copper C14500 at about 93% IACS when the part also has to machine well.
Why does my copper part come off the machine with a torn finish?
That is built-up edge, not a machine fault. Copper welds to the cutting edge under the pressure and temperature of the cut, then breaks away and takes part of the surface with it. The fix is a sharp insert with a high positive rake and a polished rake face, a heavier feed with a lighter depth of cut, a non-staining lubricant, and a separate finishing pass.
Can you machine brass dry?
Yes for C36000. The lead phase lubricates the cut and the chips carry the heat away, so dry cutting or a micro-mist is normal. At high spindle speeds a mist keeps the tool and the part at a stable temperature. Copper is different: a non-staining lubricant is worth having, and any fluid with active sulfur or chlorine is kept away from it.
How do I stop brass fittings cracking in service?
Three things. Relief anneal cold-worked or heavily machined parts at 250–350 °C to remove residual tensile stress. Keep ammonia, amines and mercury out of the environment, including cleaning agents. And where the fitting sees warm chlorinated water, specify a DZR grade with ISO 6509-1 evidence rather than a general-purpose brass.
Do you supply material certificates, and can you hold ±0.01 mm?
Both. Every order carries a mill certificate to EN 10204 3.1 with the heat number matched to the bar the part was cut from, plus PMI and a dimensional report at a stated temperature. ±0.01 mm is routine on turned brass; ±0.005 mm is available with temperature control and 100% inspection.
Related capability and material pages to read next
Precision CNC machining
3-, 4- and 5-axis milling and turning, including the brass and copper speeds, tool geometry and chip strategy described above.
High-precision components
Bores, threads and sealing faces held on brass and copper, with the inspection report to match.
Brass and copper against stainless
The other side of the same decision — where corrosion resistance or strength beats conductivity and machinability.
Send the drawing. We will tell you which alloy fits.
A STEP file, the service environment, the mating materials and the features that matter are enough to start. If a lead-free grade or a different material is the better answer, you will hear that before the quote rather than after the parts arrive.
Or send the drawing to info@xsprecisiontech.com with the alloy and the quantity and we will come back with the machining route, the tolerance we can hold and the certificate package.