The use of CNC machines has revolutionized the manufacturing and engineering fields. Straight lines and complex contours can now be easily machined with greater consistency and quality. Material selection remains a critical decision in the early design stages of a part – and it can be quite complex. Do you need something ductile? Corrosion resistant? Will heat treatment make the material more suitable for your needs? There are many options and considerations, and it's easy to get overwhelmed unless you're an expert in materials engineering. In this article, we'll cover some basics to help point you in the right direction. Here are some commonly used alloys:
Copper Alloys
Copper is not only one of the best electrical conductors, but its thermal conductivity also makes it suitable for products such as cooling system components and heat exchangers in the automotive industry. These thermal properties also make it easier to machine using CNC.
Brass Alloys
Brass is a copper-zinc alloy. C38500 brass is an excellent choice for parts requiring knurling and threading due to its strength, corrosion and wear resistance, and excellent machinability. It's a great choice for electronic hardware and contacts, fittings, and many commercial products thanks to its low strength and weight, and low cost (its machining yields high scrap returns, which translates to cost savings).
Titanium Alloys
Titanium has a high melting point, is very strong, lightweight, and resistant to corrosion, water, and salt. These are unique characteristics for many industries and applications. Ti-6Al-4V is particularly strong and lightweight, making it ideal for aircraft and aerospace applications. Ti-6Al-4VEli is very similar but adds good biocompatibility, making it a top choice for medical implants. The tolerance for grinding and polishing ½" rods of either of these two titanium alloys is set at +/-.002.
Aluminum Alloys
Aluminum is a popular choice for CNC machining. Aluminum parts can be completed in less time than any other metal, making machining aluminum and its alloys very economical. The applications for aluminum and its alloys are virtually endless.
2011 aluminum is specifically designed for machining and is commonly used in a variety of commercial products, especially electronic hardware. However, 2011 aluminum cannot be anodized or welded. 6262 aluminum is a good all-around alloy with good machinability, and can be welded and anodized.
6061 aluminum has good corrosion resistance, weldability, and formability. Like the previous two alloys, it is common in electronic hardware, and also found in piping, recreational equipment, and aircraft components.
Steel Alloys
Most steel alloys (such as 1020, 1030, S1214) can be surface hardened and are designed to provide excellent machinability. S1214 steel is specifically designed for excellent machinability, giving it a wide range of uses in commercial products, and it is perhaps the most versatile in the steel alloy family. Alternatively, S12L14 steel is developed for high-volume production and repetitive engineering.
1020 steel is a low-carbon steel with good machinability and excellent weldability, making it suitable for rivets and parts requiring strong welds. Ø50mm round bars, cold drawn, are typically supplied with an h10 tolerance or +0/-0.1mm (or +0/-0.004").
