Custom CNC Machining Copper Parts

Custom CNC Machining Copper Parts

A Brief History of Copper-Based Alloys



Copper alloys are one of the oldest metallic materials. According to the cultural relics unearthed in Egypt and West Asia, forged natural copper parts appeared around 6000 BC; bronze utensils began to be used in 5000 BC. In the 1st century BC, peoples living near the coast of the Black Sea at that time used zinc ore to add copper to copper to make brass. In the 16th century, the Englishman E. Ebener proposed to use the method of directly adding copper to zinc to produce brass. At the end of the 19th century, with the mass production of aluminum, aluminum bronze also began to appear. In the 1920s, American M.G.Corson and German O.Dahl developed beryllium bronze with high strength and good electrical conductivity, and developed new varieties of precipitation hardening in copper alloys. In the mid-1970s, American J.T.Plew and others developed a metastable decomposed copper-nickel-tin alloy with similar properties to beryllium bronze, which was used in industry on the basis of previous research.


Classification and application of copper-based alloys

Copper alloy has medium strength, easy processing, relatively fatigue resistance, beautiful color, and good electrical conductivity, thermal conductivity and corrosion resistance. It is an important branch of heavy non-ferrous metal materials. With the continuous development of the industry, the use of copper alloy parts has become more and more extensive. But how to choose the right copper alloy for your CNC project parts among the different copper base alloys? At this point, firstly we should clear that the final main application of the parts and its physical or chemical properties, such as electrical conductivity , hardness, machinability, etc., and then combine all requirements to choose the most suitable copper alloy as the raw material for your CNC machining project. In order to help you better understand copper alloys, the following articles will explain the properties and applications of various commonly used copper alloys.

CNC Machining Copper Parts

Common classification and grades of copper alloys


Comparison table of commonly used copper and copper alloy grades
Red Copper
(Pure Copper)
TP1Cu-DLPC12000C1201 SW-CuCW023A
Ag-Cu AlloyTAg0.1CuAg0.1C10400C1040 CuAg0.1 
H68 C26200C2620 CuZn33CW506L
H62CuZn40C28000C2800CZ109 CW509L
Tin BronzeQSn4-0.3CuSn4C51100C5111PB101CuSn4CW450K
CuSn5C51000C5101 CuSn5CW451K
QSn8-0.3CuSn8C52100C5210 CuSn8CW453K
Zinc-Copper-Nickel AlloyBZn18-18CuNi18Zn20C75200C7521NS106CuNi18Zn20CW409J
BZn15-20  C7541   
BZn18-10  C7350   

Properties and applications of copper alloy

Properties and applications of copper alloy
Red Copper
(Pure Copper)

1: Excellent electrical conductivity, thermal conductivity, corrosion resistance.

2: Excellent machinability, can be welded and brazed.

1: Electrically conductive, thermally conductive and corrosion-resistant components,such as wires, cables, conductive screws, housings and various conduits, etc.

2: Electrical switches, washer, rivets, nozzles, etc.

Ag-Cu Alloy

1: Excellent conductivity, fluidity and wettability.

2: Excellentmechanical properties, high hardness, wear resistance and welding resistance.

1: Vacuum solder, commutator, can also make coins, decorations and tableware, etc.

2: Contacts, conductive rings and fixed contacts of air circuit breakers, voltage controllers, telephone relays, contactors, starters, etc.


1: High strength, high hardness and strong chemical corrosion resistance.

2: Good mechanical properties of CNC milling and turning.

1: Manufacture of valves, water pipes, connecting pipes for internal and external air conditioners and radiators, etc.

2: Heat Exchangers and Condensers, Cryogenic Pipelines, Subsea Transport Pipes, etc.
Tin Bronze1: High strength, corrosion resistance and excellent casting properties.

1: Elastic elements and wear-resistant parts, etc.

2: Computer connectors, mobile phone connectors, high-tech industry connectors, electronic and electrical springs, switches, electronic product slots, buttons, electrical connectors, lead frames, vibrating sheets and terminals, etc.

Zinc-Copper-Nickel Alloy1: Excellent abrasiveness, brazing and stress relaxation resistance, high strength and elasticity, good corrosion resistance, and easy electroplating, hot and cold processing.

2: Excellent machinability, corrosion resistance and mechanical properties, suitable for cold pressure processing, and has a high surface finish after cutting.
1: Manufacture of corrosion-resistant structural parts, such as springs, sockets, covers and other parts of various precision instruments and advanced electronic components.

2: Production of precision parts for clocks, optical instruments, musical instruments, tableware, eyeglass frames and decorative engineering, etc.

What the advantages of CNC machining copper parts?

  • CNC machined copper parts have high electrical conductivity and high thermal conductivity, (the electrical and thermal conductivity of copper is second only to silver, but the price is much lower than gold and silver).

  • CNC machined copper partswith highly corrosion resistance and robust construction.

  • CNC machined copper parts have suitable strength and good ductility.

  • CNC machined copper partscan withstand extreme temperatures, easy to cast.

  • Copper parts in CNC machining are easy to form and have elegant and solemn color.

  • Excellent platability of copper parts.

Common surface treatments of CNC machined copper parts

Due to the influence of the environment, the surface of copper parts will be oxidized to different degrees, so different surface treatment processes need to be used. The commonly used surface treatment processes of copper parts are as follows:

  • Bright cleaning of copper part

  • Passivation of copper parts

  • Anodizing of copper parts

  • Electroplating treatment (zinc, nickel, chrome)

  • Chemical polishing of copper parts


After the surface protection treatment of CNC machined copper parts, it can keep bright and corrosion resistance and oxidation resistance for a long time. No matter what kind of personalized design you have, DDPROTOTYPE will wholeheartedly provide you with customized CNC machining copper parts services.

Main properties of copper-based alloys

Copper alloys have excellent electrical and thermal conductivity, moderate mechanical properties and high chemical stability. With the different types and quantities of added alloying elements, the properties of various copper alloys are quite different.


1、Electrical Conductivity

Copper alloys are better electrical conductors. The conductivity of pure copper is between 100% and 103% IACS (see copper for the definition of IACS). The addition of any solid solution alloying element will reduce the electrical conductivity of copper, and the reduction in unit atomic concentration mainly depends on the effect of the alloying element on the copper lattice, and increases with the increase of the addition amount in the solid solution range.

Electrical Conductivity


Copper has a beautiful rose red color. After adding zinc, aluminum, nickel, and other alloying elements, the color changes to golden yellow and silver white, so it can be used to make various decorations and coins.

copper Color


The copper alloy has medium strength, and the tensile strength of industrial pure copper in the annealed state is about 240MPa. The strength of copper alloys can be improved by means of solid solution strengthening, work hardening, precipitation hardening (including metastable decomposition), grain refinement and dispersion strengthening. Cold working can be used alone to harden alloys or in combination with precipitation hardening or metastable decomposition to achieve strengthening.

cnc machining copper parts

Adding any solid solution alloying element to copper will increase the strength of copper, and the degree of strengthening of the shear modulus of copper per unit atomic concentration is related to the difference between the added element and the atomic size of copper.


Generally, the machinability of copper alloys is poor, and the addition of lead, sulfur, tellurium and other elements can improve the machinability of copper alloys. According to the quality of machinability, deformed copper alloys can be divided into three categories: (1) Free-cutting alloys with machinability above 70%, including free-cutting copper containing lead, sulfur or tellurium, free-cutting brass, various lead Brass and bronze and zinc cupronickel with lead content of about 2%; (2) medium machinability alloys with machinability of 30% to 60%, including brass with copper content of 60% to 85% and lead content of about 1% (3) Difficult-to-cut alloys with machinability below 20%, including low-zinc brass, zinc cupronickel, tin bronze, copper-nickel alloy and beryllium bronze, etc. sex is 100% for comparison).

cnc machining copper parts

5、Stress relaxation resistance

The stress relaxation resistance of pure copper is poor, and the addition of soluble elements that can increase the softening temperature of copper or have a large atomic size difference from copper can improve the stress relaxation resistance of copper. Beryllium bronze, cupronickel and zinc cupronickel have the best stress relaxation resistance, followed by tin bronze and tin brass, followed by silicon bronze, and ordinary brass has the worst stress relaxation resistance. In terms of stress relaxation ability, the maximum service temperature of copper alloy is about 200°C. Brass with low resistance to stress relaxation can only be used to make parts slightly above room temperature, beryllium bronze and ternary copper-nickel alloys with tin, silicon, aluminum or zinc, even at the highest temperatures commonly used in devices, its resistance capacity for stress relaxation is still quite high.


What are the common problems encountered in the CNC machining copper parts?

Many times we will encounter such a problem when CNC machining copper materials: the stamped copper products are not cleaned, and after being placed for a week, and then cleaned, it is found that black oxides will be produced on the surface of some products.

If it is the problem of the material of the copper itself, it is difficult to solve it from the process. It can only be processed for the blackened products, and the method is also relatively simple, just do polishing for the copper parts. The purpose of copper polishing is to restore the original color and luster to the blackened surface.


Various brass alloys demonstrate the great potential of these metals for a wide range of applications. In addition to being extremely economical to produce parts by CNC machining, brass has good strength and excellent corrosion resistance potential, among a variety of other properties. For example, if your product will be used in a salt water environment, you may need to avoid C385 as much as possible and use C464 or C443 instead. Our pride lies in helping our customers succeed in metal and plastic part machining. Our industry experienced and passionate team will be happy to work with you on your next project. Contact us for more information.