CU · 10 grades
Copper Alloys
Conductivity and bearing properties, with chip control as the real challenge.
Copper alloys split into two jobs on this shop floor: electrical parts, where conductivity is the whole point, and bearing and wear parts, where the alloy is chosen for how it behaves against a steel shaft. Copper is gummy - it wants high rake, sharp edges and a lot of coolant - while free-cutting brass is the opposite and machines faster than anything except the leaded steels.
What this family does well, and where it bites
- C110 ETP copper: 100% IACS conductivity, gummy and prone to built-up edge
- C360 free-cutting brass: the reference point for a 10 on our machinability scale
- Bronze grades (C932, C954) chosen for load capacity and galling resistance
- Beryllium copper needs controlled handling - dust is a health hazard, not just a nuisance
Industries served
- Electrical & Power
- Energy & Oil & Gas
- Medical
- Marine
- Industrial Equipment
Copper Alloys grades we machine
Each grade page carries the properties as supplied, what heat treatment does or does not do to it, the achievable surface finish, starting cutting parameters and the DFM notes that matter for that specific grade.
C36000 Free-Cutting Brass
10/10130 HB (~78 HRB) · 400 MPa
The reference point for the whole scale: free-cutting brass is 100% machinability in every published table and a 10 here.
C93200 Bearing Bronze
6/1070 HB · 240 MPa
The standard bearing bronze: it machines well, it is soft enough to embed grit, and it runs against a steel shaft without galling.
C95400 Aluminium Bronze
4/10170 HB · 585 MPa
Roughly twice the strength of a tin bronze and harder to machine than it looks on a datasheet.
C26000 Cartridge Brass
8/10110 HV (~60 HRB) · 300–450 MPa
The 70/30 brass: excellent cold-forming and good machining, though without the lead it does not break a chip as cleanly as C360.
C11000 ETP Copper
6/1045 HB (annealed) · 220–340 MPa
Pure copper: gummy, prone to built-up edge and famous for long stringy chips.
C17200 Beryllium Copper
5/1038–42 HRC (aged) · 1,100–1,400 MPa (aged)
Machines like a hard brass in the annealed state and like a tool steel after ageing.
C65500 Silicon Bronze
6/10150 HV (~85 HRB) · 380–600 MPa
A tough, corrosion-resistant bronze that machines reasonably in the annealed condition and work-hardens quickly.
C51000 Phosphor Bronze
6/10100 HB (~60 HRB) · 300–600 MPa
The spring bronze: good machinability with enough tin to give real strength and fatigue resistance.
C63000 Nickel Aluminium Bronze
4/10190–210 HB · 620–790 MPa
The strongest of the standard bronze families: about the cutting speed of a stainless and the tool wear of one too.
C18200 Chrome Copper
6/1065–90 HRB · 380–550 MPa
Copper with chromium for strength: roughly 80% of the conductivity of pure copper and about twice the strength, and it machines better than C110 because it is harder.
Questions buyers ask
- Why does copper burr so badly compared to brass?
- Pure copper is soft and ductile, so the chip tears rather than shears and the edge rolls over instead of breaking. Brass has lead dispersed through it, which acts as a chip breaker at the tool edge. The fix for copper is high positive rake, very sharp uncoated tooling and enough speed to stop the material smearing.
- What should I specify for a bushing rather than bearing bronze?
- If the load is high and slow, C932 tin bronze is the standard choice. C954 aluminium bronze takes roughly twice the load and is the one for high-load, low-speed service, but it is harder to machine and more expensive. For a light-duty bushing running against a hardened shaft, a filled bronze or a PTFE-lined steel might outlast both.