Cutting Threads with Dies

Cutting Threads with Dies

Cutting Threads with Dies - A threading die is an internally threaded tool used to cut external screw threads by screwing on the workpiece. Threads are usually cut in one pass. Straight and tapered external threads up to about 37.5 mill in diameter can be cut quickly by means of thread cutting dies, such as are Fig.

A - Cutter Bit

Method of Checking the Form and Setting of the cutting tool for thread cutting by means of a template

Basically, these are similar to hardened, threaded nuts with several longitudinal grooves that expose multiple cutting edges formed by the intersection of each groove and each thread. The cutting edges at the starting end are beveled to aid in starting the dies on the workpiece. As a consequence, a few threads at the inner end of the workpiece are not cut to full depth.

Such threading dies are made of carbon or high speed tool steel. The solid type dies seldom are used in manufacturing because they have no provision for compensating for wear. The solid adjustable type, shown at (b), is split and can be adjusted over a small range by means of a screw.

This permits some adjustment to compensate for wear or to provide a variation in the fit of the resulting screw thread. These types of threading dies usually are held in a threading die stock and are rotated by hand.

Solid Threading Die	Solid Adjustable Threading Die
Threading Die Stock

In using them, a suitable lubricant is desirable in order to produce a smoother thread and to prolong the life of the die, since there is a large amount of friction because the die is fed onto the workpiece by the screw action of the die on the thread being, or already, cut.

Screw threads are cut by hand by a round or two piece adjustable die held in a hand stock.The cutting of external screw threads with thread cutting die heads in drill presses, turret lathes, threading machines or automatic lathes is a much more efficient and accurate method.