Metal · Material guide
Custom copper parts from independent machine shops
Copper is the material you reach for when conductivity is the spec: the electrical and thermal benchmark that every other metal is measured against. Pure copper machines gummy, so shops that run it plan tooling and grades accordingly. Upload a drawing and hear back from shops that cut C110, C101, and free-machining C145.
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Copper shops on OpenSpindle
Real shops that machine copper. See their equipment and talk to the person making your part.
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Grades
Copper grades shops run most
The grade sets conductivity, purity, and how easily the part machines. These are the ones you will see quoted; if yours is not here, ask when you request a quote.
C110 (ETP)
Electrolytic tough pitch copper, the standard grade for electrical work. About 100% IACS conductivity and the most widely stocked copper in bar, plate, and sheet. Machines poorly because it is soft and gummy, so expect longer cycle times than brass.
Best for Bus bars, terminals, grounding, general conductors
C101 (OFHC)
Oxygen-free high-conductivity copper, 99.99% pure with no residual oxygen. Preferred where hydrogen embrittlement, vacuum service, or high-purity electronics matter. Conductivity matches or slightly exceeds C110.
Best for Vacuum systems, RF, semiconductor, high-purity parts
C145 (tellurium)
Free-machining copper alloyed with about 0.5% tellurium. Machinability jumps to roughly 85% (near free-machining brass) while conductivity stays around 90% IACS. The default when a copper part has real machining content.
Best for Machined electrical connectors, contacts, welding tips
C102 (OF)
Oxygen-free copper without the residual deoxidizers of C101, still 99.95% pure. Similar high conductivity and good for brazing and welding where oxide-free stock is required.
Best for Brazed assemblies, conductors, cryogenic parts
C182 (chromium copper)
A precipitation-hardening copper alloy with much higher strength and hardness than pure copper while keeping about 80% IACS. Holds up under load and heat better than C110.
Best for Resistance welding electrodes, high-strength contacts
Specs
Material properties
Representative values for C110 ETP copper, the most common grade. Exact numbers vary by grade and temper.
| Property | Typical value |
|---|---|
| Density | 8.94 g/cm³ (0.323 lb/in³) |
| Tensile strength (C110) | ~32 ksi annealed to ~45 ksi hard (H04) |
| Yield strength (C110) | ~10 ksi annealed, ~40 ksi hard (varies with temper) |
| Hardness (C110, soft) | ~40 HRF |
| Electrical conductivity | ~100% IACS (the benchmark) |
| Thermal conductivity | ~390 W/m·K (excellent) |
| Machinability | Poor for pure copper (gummy chips); C145 ~85% |
| Corrosion resistance | Good; forms a protective patina |
| Joining | Readily soldered and brazed |
Copper is the reference standard for electrical conductivity (100% IACS) and one of the best thermal conductors of any metal, which is the reason to choose it over lighter or stronger alternatives.
Stock
Forms we machine it from
Plate & block
Milled bus bars, heat sinks, and prismatic parts from solid.
Round bar
Turned electrodes, terminals, and cylindrical contacts.
Sheet
Laser, waterjet, and press-brake sheet and strip.
Processes
Manufacturing methods for copper
The right process depends on part geometry, tolerances, and production volume.
Finishing
Finishes for copper
Copper is usually left bare or plated. Anodizing does not apply; the choice is whether to preserve the raw metal or plate over it for solderability and corrosion.
As-machined
Bright bare copper straight off the machine. It will oxidize and develop a patina over time, which is fine for internal or conductive contact surfaces.
Clear lacquer / coating
A thin clear coat that preserves the bright copper color and slows tarnish. Common on decorative or visible parts.
Nickel plating
A durable barrier layer that resists corrosion and provides a solderable, harder surface. The most common plating on machined copper.
Tin plating
Improves solderability and corrosion resistance while keeping good conductivity. Standard on electrical terminals and connectors.
Silver plating
Adds surface conductivity and low contact resistance for RF and high-current contacts. Used where every bit of conductivity counts.
Bead blast
A uniform matte texture, often as a base before plating or to knock down machining marks.
Copper does not anodize. If a part needs to stay bright or must be solderable, call out lacquer or the plating spec (nickel, tin, silver) with your drawing.
Applications
Where copper parts are used
Copper shows up wherever electrical or thermal conductivity drives the design.
Compare
Copper vs other materials
How copper stacks up against the other metals shops quote most.
Copper vs Brass
Brass →- Brass machines far better (free-machining C360 is roughly 100% machinability vs poor for pure copper)
- Copper has much higher electrical and thermal conductivity; brass trades conductivity for machinability and cost
- C145 tellurium copper closes most of the machining gap while keeping about 90% IACS
Choose copper when conductivity is the spec. Choose brass for machined parts, fittings, and hardware where conductivity is secondary.
Copper vs Aluminum
Aluminum →- Aluminum is about one-third the weight and machines several times faster
- Copper conducts roughly 60% more electricity and far more heat for the same cross section
- Copper costs more per pound and is heavier, so aluminum wins where weight or budget lead
Choose copper for maximum conductivity in a fixed footprint. Choose aluminum when weight, cost, or machining speed matter more.
Copper vs Stainless steel
Stainless steel →- Stainless is far stronger and harder and resists corrosion without a coating
- Copper conducts electricity and heat many times better; stainless is a poor conductor
- Copper is softer and gummier to machine, while stainless is hard but not gummy
Choose copper for electrical or thermal parts. Choose stainless for strength, hygiene, and structural corrosion resistance.
Questions
Frequently asked questions
C110 is electrolytic tough pitch (ETP) copper, the standard electrical grade at about 100% IACS, and it is the most widely stocked. C101 is oxygen-free high-conductivity (OFHC) copper, 99.99% pure with the residual oxygen removed, so it avoids hydrogen embrittlement and suits vacuum, RF, and high-purity electronics. For most conductors C110 is fine; specify C101 when purity or vacuum service is required.
More materials
Other materials on OpenSpindle
Get copper part quotes
Upload a drawing once and compare quotes from independent shops that machine, turn, and plate copper.
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