TABLE OF CONTENTS CNC lathes can produce a very high quality thread in addition to the variety of turning and boring operations, in a single setup of the machined part. This is a very attractive feature for manufacturers and many machine shops have purchased a CNC lathe for that reason along. Any secondary operation requires additional setup, increasing the cost of production.
Single point thread cutting - typically known as a single point threading - uses a tool holder similar to other tool holders, but contains one special threading indexable insert, which may have one, two or three tips. Generally, the shape and size of the threading insert must correspond to the shape and size of the finished thread - Figure 38-1.
By definition, a single point threading is a machining process of cutting a helical groove of a specific shape with a uniform advancement per spindle revolution. The shape or form of the thread is mainly determined by the shape and mounting position of the cutting tool. The uniformity of advancement is controlled by the programmed feedrate.
The most common thread form used in CNC programming is the familiar V-thread (in the shape of the letter V) with a 60 included angle. There is a large variety of the V-shape forms in manufacturing, including metric and English threads. Other forms include trapezoidal shapes such as metric trapezoid, ACME and worm...
