What are the characteristics of brass? Why is brass so commonly used in CNC manufacturing? And what’s the composition of brass?
Brass is an alloy of copper and zinc (also known as a copper-zinc binary alloy – we call it brass or ordinary brass). Changing the zinc content in brass can obtain a material with different mechanical properties. The higher the zinc content in brass, the higher the strength, and the lower the plasticity.
The zinc content of brass commonly used in the industry does not exceed 45%. A high zinc content causes the brass to become more brittle and can deteriorate the alloy’s performance and reduce quality. To combat this and improve the performance of brass, we can add some extra alloying elements – allowing us to obtain a special composition of brass. The most common alloying elements are silicon, aluminium, tin, lead, manganese, iron, and nickel (thought here are, of course, others). Adding aluminium to brass can increase the yield strength and corrosion resistance of brass and slightly reduce plasticity.
Brass containing less than 4% aluminium has good properties for processing and casting. Adding 1% tin to brass can significantly improve the resistance of brass to seawater and marine atmospheric corrosion, hence we call it ”Navy brass”. Tin also improves the machinability of brass. The main purpose of adding lead to brass is to improve machinability and wear resistance. Lead also has little effect on the strength of brass.
Manganese brass has good mechanical properties, thermal stability, and corrosion resistance; adding aluminium to manganese brass can also improve its performance and obtain a smoother surface casting. (We can also provide a material certificate for all materials that we are using – if you would like to find out more, please do not hesitate to get in touch.)
For copper machined parts, Weimi can do the following surface treatments:
Chemical treatment: An acidic or alkaline solution that reacts chemically with oxides and oil on the surface of the workpiece. The solution dissolves and removes the rust scale and oil on the surface of the workpiece. A hairbrush roller or #304 stainless steel wire (steel wire brush roller made of acid and alkali resistant solution) can be cleaned to achieve the purpose.
Mechanical treatment: Shot blasting and grinding. Shot blasting is a cleaning method that uses centrifugal force to accelerate the projectile and throw it to the workpiece for rust removal and cleaning, however, shot blasting has poor flexibility. If the equipment structure is complicated, and there are many wearing parts (especially the blades and other moving parts), these can wear more quickly so the maintenance time and cost is high.
Surface treatment with shot blasting has a large impact force and a cleaning effect. However, the treatment of thin plate workpieces by grinding or sandblasting can easily deform the workpieces as the steel shot hits the surface of the workpiece (whether shot blasting or grinding) and may deform the metal substrate.
As ferric oxide has no plasticity, it peels after being broken, and the oil film lingers on this material Therefore sandblasting and grinding cannot completely remove oil stains on workpieces and it’s not a method we would recommend.
Electrochemical method: This method use electrode reactions to form a coating on the surface of the workpiece. The main methods are:
– Electroplating: In the electrolyte solution, the workpiece is the cathode, and the process of forming a plating layer on its surface under the action of external current is called electroplating. The plating layer can be metal, alloy, semiconductor or containing various solid particles, such as copper plating and nickel plating.
– Oxidation: In the electrolyte solution, the workpiece is the anode, and the process of forming an oxide film layer on the surface under the action of external current is called anodization, such as the anodization of aluminium alloy.
Find out more about our machining services and surface treatments on brass parts by filling in our enquiry form.