Тісті кескіш құрал және металл кесу процесі

Tool with teeth used to cut metal
Broaching is a machining process that uses a toothed tool, called a broach, to remove material. There are two main types of broaching: linear and rotary. In linear broaching, which is the more common process, the broach is run linearly against a surface of the workpiece to produce the cut. Linear broaches are used in a broaching machine, which is also sometimes shortened to broach. In rotary broaching, the broach is rotated and pressed into the workpiece to cut an axisymmetric shape. A rotary broach is used in a lathe or screw machine. In both processes the cut is performed in one pass of the broach, which makes it very efficient. Broaching is used when precision machining is required, especially for odd shapes. Commonly machined surfaces include circular and non circular holes, splines, keyways, and flat surfaces. Typical workpieces include small to medium sized castings, forgings, screw machine parts, and stampings. Even though broaches can be expensive, broaching is usually favored over other processes when used for high quantity production runs. Broaches are shaped similar to a saw, except the height of the teeth increases over the length of the tool. Moreover, the broach contains three distinct sections: one for roughing, another for semi finishing, and the final one for finishing. Broaching is an unusual machining process because it has the feed built into the tool. The profile of the machined surface is always the inverse of the profile of the broach. The rise per tooth (RPT), also known as the step or feed per tooth, determines the amount of material removed and the size of the chip. The broach can be moved relative to the workpiece or vice versa. Because all of the features are built into the broach, no complex motion or skilled labor is required to use it. A broach is effectively a collection of single point cutting tools arrayed in sequence, cutting one after the other; its cut is analogous to multiple passes of a shaper.

The concept of broaching can be traced back to the early 1850s, with the first applications used for cutting keyways in pulleys and gears. After World War I, broaching was used to rifle gun barrels. In the 1920s and 30s the tolerances were tightened and the cost reduced thanks to advances in form grinding and broaching machines.

Broaching was originally developed for machining internal keyways. However, it was soon discovered that broaching is very useful for machining other surfaces and shapes for high volume workpieces. Because each broach is specialized to cut just one shape, either the broach must be specially designed for the geometry of the workpiece or the workpiece must be designed around a standard broach geometry. A customized broach is usually only viable with high volume workpieces, because the broach can cost US$15,000 to US$30,000 to produce. Broaching speeds vary from 20 to 120 surface feet per minute (SFPM). This results in a complete cycle time of 5 to 30 seconds. Most of the time is consumed by the return stroke, broach handling, and workpiece loading and unloading. Also, there are limits on the size of internal cuts. Common internal holes can range from in diameter but it is possible to achieve a range of Surface broaches' range is usually , although the feasible range is
Tolerances are usually ±0.002 in (±0.05 mm), but in precise applications a tolerance of ±0.0005 in (±0.01 mm) can be held. Surface finishes are usually between 16 and 63 microinches (μin), but can range from 8 to 125 μin. but is still possible.

Solid broaches are the most common type; they are made from one solid piece of material. For broaches that wear out quickly shell broaches are used; these broaches are similar to a solid broach, except there is a hole through the center where it mounts on an arbor. Shell broaches cost more initially, but save the cost overall if the broach must be replaced often because the pilots are on the mandrel and do not have to be reproduced with each replacement.