Thread Milling is a method for producing a thread by a milling operation.
The most common way to produce a thread is still by tapping and turning but today we see more and more milling and this is because CNC milling machines with three simultaneous axes are very popular. These can now be found in every small workshop.
To perform a Thread Milling operation, a helical interpolation movement is required. Helical interpolation is a CNC function producing tool movement along a helical path. This helical motion combines circular movement in one plane (x,y coordinate) with a simultaneous linear motion in a plane perpendicular to the first (z coordinate).
Thread milling tools are based on indexable multitooth inserts. The cutter rotates around itself at high speed and at the same time moves along the helical path. All the teeth are machined simultaneously so every tooth creates one pitch. At the end of the operation all pitches are combined into one complete thread and that by one pass only. This result is achieved with high accuracy inserts and use of a CNC milling machine.
Many don't realize it but you can also thread mill around a boss for large diameter OD's where a custom die is price prohibitive.
A big drawback for many years had been the need to write the CNC programs manually in the absence of helical interpolation routines now commonly available on CNC machining centers.
Vargus' TM Gen, a PC-based program, solves this by guiding you through a few simple steps to define the thread milling application and then provides all the information needed to complete the job - the best tool to use, the optimal machining data, and the actual G-code for all popular controllers.
Vargus TM Gen helps you take the guesswork out of thread milling. You can download the TM Gen program, free-of-charge. When on the site, be sure to register for automatic version update notifications!