Wexmar handles C110 copper CNC machining for electrical, thermal and grounding components. C110, also called electrolytic tough pitch (ETP) copper, offers about 100 percent IACS conductivity, which makes it the default for bus bars, terminals, lugs and heat spreaders. It is also one of the harder metals to machine cleanly. Our Canastota, NY shop turns, mills and Swiss-machines copper parts from rod, bar and plate for OEM and government customers.
C110 copper machinability
On the copper-alloy scale, where C360 free-cutting brass equals 100 and runs several times faster than 1212 steel, C110 rates approximately 20. That low number does not mean copper is hard. It means copper is soft, ductile and gummy. It tends to build up on the tool edge, tear rather than shear, and produce long continuous chips that wrap tools and mar finished surfaces. Cycle times run longer than on brass because the chip has to be managed rather than simply cut faster.
Tolerances and surface finish on copper parts
Typical tolerances on precision copper parts are plus or minus 0.001 in. on milled features and plus or minus 0.0005 in. on turned diameters, with tighter limits reviewed case by case. A 63 Ra finish is standard, and 32 Ra is typical on turned contact faces with sharp tooling. Flatness on thin bus bars is limited more by the stock and by stress release than by the machine, so we discuss flatness callouts before quoting. All figures are typical, not guaranteed.
Machining gotchas: built-up edge, burrs and softness
Copper rewards very sharp, polished, high-positive-rake tooling. Uncoated polished carbide or DLC-coated tools resist built-up edge better than general-purpose coated inserts. We run high surface speeds with generous flood coolant to keep material from welding to the edge. Points our programmers watch on every copper job:
- Burrs: copper rolls large, soft burrs on every exit edge, so deburring is planned in the program with chamfer passes and back-side tools rather than left to hand work.
- Chip control: long stringy chips need chipbreaker geometry, peck drilling and interrupted cycles, especially on Swiss machines running unattended.
- Clamping marks: annealed and half-hard copper dents easily, so we use soft jaws, protective pads and controlled clamp pressure.
- Tapped holes: copper tears threads, and form taps or thread milling usually produce cleaner threads than cut taps.
- Oxidation: bare copper tarnishes quickly, so finished parts are cleaned, dried and packaged to limit handling.
Plating and finish options
Most C110 electrical parts are plated after machining. Tin, silver and nickel plating, along with clear anti-tarnish coatings, are applied through qualified outside processors. Annealing to restore softness after forming is also arranged outside. We note masked contact areas per the drawing and ship parts with material certs when required.
Common C110 copper parts and processes
- Bus bars, shunts and ground straps with drilled and tapped holes: horizontal milling on our Mazak pallet machines
- Terminal lugs, contacts and connector pins up to 32 mm diameter: Swiss machining on Maier MLK-32 machines
- Heat sinks, cold plates and heat spreaders: horizontal machining centers
- Electrode blanks and welding tip blanks: CNC lathes with live tooling
- Grounding studs and bus bar spacers: lathes or Swiss, depending on size
Cost index compared with 6061 aluminum
| Material | Approx. machinability (scale noted) | Cost index vs 6061 | Notes |
|---|---|---|---|
| C110 copper | 20 (C360 = 100) | 2.2 | High conductivity, gummy |
| C360 brass | 100 (C360 = 100) | 1.2 | Free-cutting reference alloy |
| C260 cartridge brass | 30 (C360 = 100) | 1.6 | Ductile, lower conductivity |
| C932 bearing bronze | 70 (C360 = 100) | 1.6 | Leaded, easy chips |
| 6061-T6 aluminum | ~180 (1212 = 100) | 1.0 | Lighter conductor, baseline |
| 303 stainless | ~78 (1212 = 100) | 1.8 | Structural, not conductive |
The figures are typical and illustrative for a comparable part; actual quotes depend on geometry, quantity, tolerances and mill pricing. Copper prices follow the commodity market, so quotes carry a material validity window.
Applications for machined copper
C110 parts serve electrical and connector manufacturers, switchgear and power distribution builders, instrumentation makers and defense build-to-print programs. Where a part needs some conductivity but also free-cutting behavior, C360 brass is sometimes a practical alternative; where strength and wear matter more, consider C932 or C954 bronze. Our industries page lists the markets we supply.
Getting a quote
To price copper parts, upload a drawing for an instant estimate or call (315) 400-2654. A human estimator confirms every quote, including plating requirements and current copper pricing.