Brass is a workable metal that is commonly used in various industries due to its various desirable properties. This alloy contains copper, zinc, and other metallic elements such as magnesium, iron, and lead, all of which contribute to its machinability.
In this article, we‘ll cover the properties of brass, materials used to customize brass parts, applications for brass parts, and factors to consider when selecting brass for machining projects.
What properties of brass make it suitable for CNC machining?
As mentioned earlier, brass contains mostly copper and zinc, and these metals give brass additional properties.
1. High machinability
Brass is one of the metals with high machinability, a characteristic that is due to the presence of lead in its composition. Brass has machining characteristics such as high feed rate, good ductility and flexibility.
2. Corrosion resistance
One of the characteristics of brass suitable for processing is its corrosion resistance, this characteristic is one of the reasons for the long service life of brass parts. In addition, it also makes parts made of brass material suitable for use in liquid environments, however, the degree of corrosion resistance depends on the amount of iron and aluminum and other components.
3. Ductility
Brass is extremely ductile due to its copper content. However, the ductility of this metal is even better than that of copper. The high ductility of brass makes it a preferred choice for machining projects due to the ease with which machinists can work this metal into different shapes.
4. Strength and hardness
Brass is not only easy to machine, but it is also very strong. Although it is not as strong as steel, it is quite durable.
5. Aesthetics
One of the main considerations in machining is the aesthetics of the finished product. Brass has a bright golden color, and its natural finish means that brass machined parts can be used with essentially no additional surface treatment.
Types of Brass Grades for CNC Machining
Brass comes in different grades, depending on the copper and zinc composition it contains. Variations in these compositions also affect the application characteristics of different grades of brass. This section describes the advantages, disadvantages and applications of several of these grades.
1. Brass C360
Often referred to by machinists as free machining brass, this alloy is the most commonly used brass grade in machining and is known for its high machinability and tensile strength. Its high machinability is attributed to the approximately 3% lead content in its composition. Manufacturers use it to machine brass custom parts such as electrical equipment, fittings, or screws.
Pros.
Easy to machine;
Corrosion resistance;
Good tensile strength.
Cons
Lead content may cause problems if used for medical purposes.
Susceptible to acids.
2. Brass C230
Mechanics refer to this grade of brass as red brass or Nordic brass. It is of medium strength and has good resistance to rust, C230 is also popular for its resistance to weathering and dezincification. It is suitable for customized parts such as rotor bars and J-bends.
Pros.
Resistance to dezincification;
Moderate tensile strength;
Corrosion resistance.
Disadvantages
May not withstand corrosion in harsh environments.
3. Brass C220
Mechanics refer to this alloy as commercial bronze. Despite its similarity to bronze in name, its composition is still a brass alloy due to its high copper content. It has good machinability, strength and ductility.
Pros.
Excellent corrosion resistance;
Good machinability;
High ductility and strength.
Disadvantages
May require additional annealing after exposure to harsh environments.
Surface Finish Options for CNC Machined Brass
Brass itself does not have a natural coating; however, the natural golden color finish of brass means you can use a machined brass part as an end product. If the part has other cosmetic uses, you may need to externally polish it. Here are a few optional surface finishes for brass CNC machined parts:
1. Machined Surfaces
Machined finished brass parts are also more aesthetically pleasing due to the fact that brass has a naturally bright golden yellow surface. Not much, in most cases, the focus of the parts directly using the machined surface usually focuses on its functionality rather than aesthetics.
2. Polishing
This involves polishing the surface of the customized brass parts using grinding wheels and abrasive discs, the abrasives on the discs help to remove impurities and make the surface smoother.
3. Electroplating
This surface treatment method uses electroplating to combine the molecules of another metal to the surface of the brass parts. The metals used for electroplating include aluminum, stainless steel, etc. The surface after electroplating is usually bright or smooth.
4.Honing
This surface treatment method uses a grinding stone to polish the surface of the finished product, which can form a cross pattern on the surface of the brass parts.
Factors to consider when selecting brass for CNC machining
Because brass metal comes in a variety of grades, you need to consider which grade has the right properties for your project. Therefore, it would be helpful if you could make a list of factors to consider before settling on a particular grade. We have listed below some of the factors to consider when machining brass parts.
Time required to machine the part
Lead times vary from project to project, and this is an important factor in deciding which grade of brass to use. When it comes to CNC machining brass, C360 alloy is one of the best grades for machinability. For this reason, C360 is the most popular material to use if you have an urgent need for custom brass parts. However, if you need more properties than just machinability, you may want to consider other grades such as C230 or C220.
Design for Manufacturability
Design for manufacturability principles are critical in any machining process. While brass is relatively easy to machine, you must ensure that the design of the part is not overly complex for machining. It‘s also a good idea to minimize the number of machine tool fixtures required, which can help reduce the machining costs of your project.
Applications for finished parts
The various compositions of brass mean that they all have different strengths and weaknesses, which means that where you plan to use the part will influence the choice of different brasses. For example, if the part is to be used for underground piping, it is best to use C230 grade brass.
Applications for Machined Brass Parts
Applications for the CNC brass machining process include manufacturing the following parts:
hinges
knobs
Water pipes
clocks
jewelry
Gears
Door ornaments, etc.
