Titanium

When CNC machining titanium, low cutting speeds are recommended. Tool tip temperatures can be easily increased by higher cutting speeds, which can compromise tools. Other related factors include sharp tools regularly replaced at the first sign of wear, feed rates high enough to prevent work hardening and the generous use of coolant.

High speed steel (HSS) drills are excellent for Titanium so long as it is sharp, but carbide tipped drills still provide the best results and deep hole drilling. Because titanium is not a great conductor of heat, much of the heat goes into cutting tools, highlighting the need for sharp and well-maintained tools.

Some of the factors that can make CNC machining titanium difficult are:

1. Poor Thermal Conductivity - cutting tools end up taking the burden of heat generation.
2. “Sticky” or “Gummy” Properties - can lead to problems with long “stringy” chips as well as creating built-up edge.
3. Low Modulus of Elasticity - leads to spring back and chatter while machining.
4. High Work Hardening Tendency - further increases difficulty of machining.

Grade 4 titanium is generally considered the strongest pure titanium, although the least moldable. It also has excellent corrosion resistance and outstanding ductility. Titanium is also lighter weight than some steels, such as stainless, due to its low density.