From CNC Programming Handbook: A Comprehensive Guide to Practical CNC Programming, Second Edition
THREADING ON CNC LATHES
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.
Figure 38-1: Comparison of the thread form and the threading tool shape
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.
Form of a Thread
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...
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TERMINOLOGY OF THREADING Threading is a relatively large subject, in fact, it is large enough to have a whole book dedicated to it. As subjects of this kind usually are, threading has its own...
THREADING ON CNC LATHES In a single setup, CNC lathes can produce very high quality threads, in addition to turning, boring, grooving and other operations. This is a very attractive feature for...
THREADING FEED AND SPINDLE SPEED In threading, the choice of the cutting insert, the spindle speed and feedrate selection are rather restricted. Both, the cutting tool and the feedrate are...
THREADING FEED AND SPINDLE SPEED Regardless of any active cutting motion, there is always a feedrate involved - this feedrate controls how effectively the tool removes material in various operations...
THREADING PROCESS Threading is one of the most automated programming tasks in modern machine shop, yet it could be one of the more difficult operations done on a CNC lathe. Initially, it may seem an...
