Titanium and titanium alloys are most often found in aerospace applications due to its lightweight and high strength.
However, other industries are discovering the benefits of titanium as well. One of the more common alloys is Ti 6AL-4V. It is generally machined at a hardness ranging from approx. 28 to 37 Rc.
One the characteristics that makes titanium difficult to tap is its tremendous elastic memory. When tapping, the material closes tightly around the cutting tool, generating friction and heat, resulting in increased wear of the cutting edges. This material also easily work hardens.
To successfully tap titanium, a tap specifically designed with additional clearance to overcome the extreme elastic memory of the material is recommended.
Tap clearances would include extra back taper of the threads from the front to the back of the thread section, full radial clearance in the threads across the tap lands, and additional relief in the tap chamfer area.
All of these features are used to reduce friction and heat. In some cases, larger H limits might be required to overcome the shrinkage.
Premium grade materials are also used for heat and wear resistance. Obviously we offer these in our standard product lines.
Lubrication and proper pre-tapped hole size are vital to success. A compatible tapping fluid should be used that provides plenty of lubrication to reduce friction.
The drill should be selected to produce the largest hole size that is allowed by the thread class callout (2B or 3B).
Due to the additional clearances required on these tools, positive feeding of the tap is highly recommended.