Machining of Titanium
There has been a trend in the last five years for more components to be made from ‘hard’ and ‘exotic’ materials so as to extend part life. Titanium is one such metal that is growing in popularity across a range of industries but most noticeable in automotive, heavy lifting and medical applications.
Titanium can withstand long periods of exposure to salt water, and is a very ductile material that can be worked into many shapes. It does not conduct heat or electricity well and it is as strong as steel but much less dense.
Titanium does not conduct heat well and as such all of the energy generated through friction will instead be stored in the cutting edge. This means that in order to extend tool life, any machining must be carried out at slower speeds. By reducing your cutting speed by a third you can extend part life by nearly 80%. Despite this low heat conductivity, coolant is still needed due to Titanium’s high chemical reactivity. Titanium is that it is a highly reactive to oxygen and nitrogen. This causes noticeable problem if exposed to high temperatures in cutting and can actually start to smear the metal and ruin cutting tools. As such coolant should be used and it is advisable to use carbide cutting tools when machining. It is also advisable to vary the depths of your cuts to spread out the tool wear if you are encountering issues.
Titanium has a low modulus of elasticity, which is one property that makes it so popular with aircraft manufacturers but does represent a challenge when machining. Titanium can sometimes deflect the cutting tool, sliding it along the material rather than removing material. This causes chatter, damages your component and can also generate heat and ruin tooling. It’s important that machine set up is stiff and rigid and this is especially true of the spindle and tool.
Forged Titanium can develop stress which will affect the machining process. The only real way to combat this is through heat treatment of the metal, but these must be applied before any machining process begins.
Titanium is not necessarily difficult to machine if you have the knowledge and experience, and that’s where it can be valuable to outsource unfamiliar materials to suppliers like Bronte Precision. We can machine a wide range of different materials and where you may not have the knowledge it may make more sense to use ours. We are ISO 9001 certified and based in Bradford, West Yorkshire.