Brass
What is brass?
Brass is a metal alloy made primarily of copper and zinc. It is one of the best-known copper alloys and is widely used for components manufactured in the machinery industry. The exact composition of brass varies depending on its application, and elements such as lead, aluminium or nickel can be added to improve the material’s machinability, strength or corrosion resistance.
From a machining perspective, brass is a valued material because it is easy to cut, dimensionally accurate to machine, and often produces an excellent surface finish. Thanks to these properties, brass is used in many precision parts where machinability and dimensional stability are important.
Properties of brass in machining
The properties of brass make it a highly practical material in machine shops. It forms chips easily and usually does not cause significant tool wear, which enables high cutting speeds and efficient production. In addition, brass conducts heat and electricity well, making it suitable for many technical applications.
Key properties of brass include good corrosion resistance, relatively high strength and good formability. The structure of the material also allows versatile machining methods such as turning, milling and drilling. In many cases, brass produces uniform chips and good surface roughness without particularly demanding cutting parameters.
Typically, the physical and mechanical properties of brass fall within the following ranges:
- density about 8.4–8.7 g/cm³
- tensile strength about 250–600 MPa
- melting point about 900–940 °C
- thermal conductivity about 120–230 W/(m·K)
The amount of alloying elements can significantly affect these values. For example, leaded brass alloys are known for their especially good machinability.
Brass alloys and material groups
Brass alloys can be divided into several groups according to their composition and intended use. The most common groups are lead-free brass alloys, leaded brass alloys and various special brasses.
In lead-free brass, the main alloying elements are copper and zinc. Such alloys are often used in drinking water systems and other applications where good corrosion resistance and safety are required from the material.
Leaded brass contains small amounts of lead, which significantly improves the machinability of the material. This makes it a very popular material for precision parts manufactured in machine shops, such as valves, fittings and threaded components.
Special brasses also contain other alloying elements such as aluminium, iron or nickel. These can be used to improve, for example, wear resistance, strength or corrosion resistance in demanding operating environments.
Applications of brass in the machinery industry
Brass is a versatile material used both in the machinery industry and in many other technical fields. Thanks to its good machinability, it is well suited for manufacturing precision components that require dimensional accuracy and a consistent surface finish.
In machine shops, brass is often used in valves, fittings, bearing components and various threaded parts. The material is also used in piping and water connections because it withstands moisture well and does not rust in the same way as many iron-based materials.
In addition, brass is widely used in decorative and mechanical components such as locks, door handles and various instruments. Its good formability and appearance make it a popular material for products that combine technical and visual requirements.
Corrosion of brass and dezincification
Although brass generally has good corrosion resistance, it is subject to a specific form of corrosion known as dezincification. In this phenomenon, the zinc in the brass dissolves out of the material due to a chemical reaction, leaving behind a more porous copper structure.
Dezincification can weaken the mechanical strength of the material and cause damage, particularly in piping or in moist environments. To reduce this risk, alloying elements such as aluminium or nickel can be added to brass to improve its corrosion resistance and stability.
Brass as a machinable material
From a machining standpoint, brass is among the materials considered extremely easy to work with. Its cutting properties are generally better than those of many steels, enabling fast production without excessive tool wear.
Brass is well suited to both automatic turning and CNC machining. Its uniform structure facilitates the manufacture of precision parts, and a good surface finish is often achieved without extensive post-processing. For this reason, brass is a common material for many small and medium-sized components produced in machine shops.
Summary
Brass is a metal alloy of copper and zinc, known especially for its good machinability, corrosion resistance and wide range of applications. Its alloy composition can be adjusted by adding various metals, allowing the material’s properties to be optimised for machining, wear resistance or corrosion resistance.
In the machinery industry, brass is an important material, especially for precision parts and joining components where good machinability, dimensional accuracy and reliable performance are required.
