The popularity of titanium alloys as a material for structural and other parts has grown exponentially in the past few years. Unfortunately, many manufacturers find that working with titanium is challenging due to the physical characteristics of the metal and its chemical composition. For example, titanium is a poor conductor of heat and more heat is generated when machining titanium than many other metals.
According to Sandvik Coromant, this exposure of the cutting edge to higher temperatures along with high-pressure cutting may cause premature tool wear. Plus, titanium has a tendency to smear during machining, and this can cause chips to weld to the insert, thus causing edge line problems when re-entering the cut. There’s also an increased risk of chattering caused by titanium’s elasticity.
To deal with these problems, the insert maker recommends these general guidelines for machining titanium:
Use relatively low cutting speeds
Use sharp cutting edges
Optimize feed rates and avoid idling while in cut
Use large volumes of coolant, preferably at high pressure through spindle and tool
Replace cutting edges at first sign of any wear
Employ climb (down) milling wherever possible
According to Gosiger Application Engineers, manufacturers must also look at the complete picture, which means thinking about the tooling, fixtures, machine spindle rigidity and speed, and the CNC machine’s control system. Of course the heart of the process is the CNC machine, itself. That’s why it’s important to have equipment with a rigid spindle and tool holder to eliminate the vibrations that cause out-of-tolerance parts. It’s also critical to maintain a constant cutting feed rate, because if the spindle starts to slow down, the tool may burn up. Additionally, the machine’s control must be capable of maintaining consistent acceleration and deceleration, and to quickly process data.
The experts at Gosiger can tell you much more about machining titanium and many other difficult-to-machine materials. Simply contact Gosiger, Inc.
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