---
title: "Copper CNC Machining | C110 ETP, C101 OFHC, C145 | OpenSpindle"
description: "Get quotes for custom copper parts from independent machine shops. C110 ETP, C101 OFHC, and free-machining C145 tellurium copper, machined, turned, and plated. Upload a drawing."
canonical: https://openspindle.com/materials/copper
---

# 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.

## Copper shops on OpenSpindle

Real shops that machine copper. See their equipment and talk to the person making your part.

[Browse all copper shops](https://openspindle.com/manufacturers?material=C110%2CC145)

## 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

## Material Properties

Representative values for C110 ETP copper, the most common grade. Exact numbers vary by grade and temper.

| Property | 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

- **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 That Run This Material

- [CNC Machining](https://openspindle.com/capabilities/cnc-machining.md) -- Milled bus bars, heat sinks, and prismatic parts from plate and block.
- [CNC Turning](https://openspindle.com/capabilities/cnc-turning.md) -- Turned electrodes, terminals, and contacts from round bar.
- [Sheet Metal & Press Brake](https://openspindle.com/capabilities/sheet-metal-fabrication.md) -- Cut and formed bus bars, shields, and strap from copper sheet.
- [Waterjet Cutting](https://openspindle.com/manufacturers?capability=Waterjet%20cutting) -- Cold cutting for thick copper plate with no heat-affected edge.
- [EDM](https://openspindle.com/manufacturers?capability=EDM) -- Copper itself is a common EDM electrode material for sinker work.
- [Laser Cutting](https://openspindle.com/manufacturers?capability=Laser%20cutting) -- Flat cuts in thinner copper sheet, on lasers set up for reflective metal.

## Finishes

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

- Electrical bus bars & terminals
- Heat sinks & thermal management
- RF & microwave
- EDM electrodes
- Plumbing & fittings
- Waveguides
- Power distribution
- Decorative

Copper shows up wherever electrical or thermal conductivity drives the design.

## How It Compares

How copper stacks up against the other metals shops quote most.

### [Brass](https://openspindle.com/materials/brass.md)

- 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

**Verdict:** Choose copper when conductivity is the spec. Choose brass for machined parts, fittings, and hardware where conductivity is secondary.

### [Aluminum](https://openspindle.com/materials/aluminum.md)

- 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

**Verdict:** Choose copper for maximum conductivity in a fixed footprint. Choose aluminum when weight, cost, or machining speed matter more.

### [Stainless steel](https://openspindle.com/materials/stainless-steel.md)

- 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

**Verdict:** Choose copper for electrical or thermal parts. Choose stainless for strength, hygiene, and structural corrosion resistance.

## Frequently Asked Questions

### What is the difference between C110 and C101 copper?

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.

### Why is copper hard to machine?

Pure copper (C110, C101) is soft and ductile, so it tends to smear and produce long, stringy, gummy chips rather than breaking cleanly. That means slower cycle times, sharper tooling, and more attention to chip control than brass or aluminum. If a part has real machining content, free-machining C145 tellurium copper cuts far better while keeping most of the conductivity.

### What is C145 tellurium copper?

C145 is copper alloyed with about 0.5% tellurium to make it free-machining. Its machinability rises to roughly 85%, close to free-machining brass, while electrical conductivity stays around 90% IACS. It is the default grade when you need both good conductivity and a part that machines efficiently, such as connectors, contacts, and welding tips.

### Can copper be plated?

Yes, and plating is common. Nickel, tin, and silver are the usual choices: nickel for a hard corrosion barrier, tin for solderability, and silver for the lowest contact resistance in RF and high-current parts. Bare copper can also be left as-machined or clear-lacquered to preserve the bright color. Copper does not anodize.

### Why choose copper over aluminum for a heat sink or conductor?

Copper conducts roughly 60% more electricity and significantly more heat than aluminum for the same cross section, so it moves more current or heat in a fixed footprint. The tradeoffs are weight (copper is about three times denser) and cost. Choose copper when space is tight and conductivity is the priority; choose aluminum when weight or budget lead.

### Does copper corrode?

Copper resists corrosion well and does not rust like steel. In air it forms a protective oxide and, over time, a patina that actually shields the metal underneath. For parts that must stay bright or solderable, a clear lacquer or a nickel or tin plating keeps the surface stable.

### What file formats should I send for a copper part?

STEP, IGES, X_T, DWG, DXF, or a dimensioned PDF. Include the grade (for example C110 or C145), critical dimensions and their tolerances, quantity, and any finish such as bright/lacquered or nickel, tin, or silver plating.

## Related Materials

- [Brass](https://openspindle.com/materials/brass.md)
- [Aluminum](https://openspindle.com/materials/aluminum.md)
- [Stainless Steel](https://openspindle.com/materials/stainless-steel.md)
- [Carbon Steel](https://openspindle.com/materials/carbon-steel.md)
- [Titanium](https://openspindle.com/materials/titanium.md)
- [Delrin](https://openspindle.com/materials/delrin.md)

## Get copper part quotes

Upload a drawing once and compare quotes from independent shops that machine, turn, and plate copper.