Brass is an alloy of copper and zinc, but often other elements such as aluminium, iron, manganese, tin and lead are added.
There are two basic classes of brass:
- Alpha alloys – less than 37% zinc – ductile and can be cold worked.
- alpha/beta or duplex alloys – 37-45% zinc – have limited cold ductility and are harder and stronger.
- CZ108 Brass – A common, high purity brass alloy suited to many general applications and often used used in general electrical engineering (sheet/strip products). Hardness and strength are both excellent and this alloy is well suited to cold forming.
- CZ112 Naval Brass – added tin gives better corrosion resistance.
- CZ116 Higher Tensile Brass
- CZ121 Free Machining Brass – cold working is poor.
- CZ126 Arsenical Brass – increased resistance to corrosion. Its ductility and strength is better than other common alloys.
- CZ131 Turning and Riveting Brass
- Yellow brass – An American term for 67/33 or 65/35 brass.
When machining brass in the lathe or milling machine I tend to work dry and don’t use any form of cutting oil. For the lathe tools I use a very shallow tool.
If you want a very bright finish then use a very fine wet and dry paper and then finish with wire wool. Note that brass tarnishes quite quickly and so you will either have to buff regularly or use a lacquer.