internal threading tool / lathe / indexable insert

Thread turning is another option for making internal threads when tapping conditionals are not optimal, such as parts with large diameters or in difficult to cut materials. Thread turning is most often performed on a lathe with a cylindrical workpiece, and uses an indexable carbide insert with a boring bar. When boring bars are too large for the size of hole, a solid carbide threading bar can be used. In thread turning, the workpiece rotates as the cutting tool moves axially to create a continuous thread path. Like thread milling, it normally takes multiple passes to generate a full thread profile. Unlike a thread milling cutter, all the material removal is accomplished with only one cutting edge engaged. Removing only a fraction of the thread depth in each pass keeps the cutting edge from being overloaded.