Broaching is mainly used to machine the inner and outer surfaces. According to the different surface parts to be processed, it can be divided into outer surface broaching and inner surface broaching. The broaching process has the following characteristics: There are many knives working at the same time during broaching. Finishing and finishing can be done in one stroke. The cutting speed of the usual broaching is 2 to 8 m/min. It is known from the relationship between the broaching speed and the surface roughness. At this cutting speed, built-up edge is likely to occur. The cutting speed is reduced. The machine tool is prone to creepage spacing; the speed is higher. It is easy to generate vibration (because of technological advances, there are now broaching machines with a speed higher than 4Om/min).
Broaching is a closed process. A chip pocket is left between the teeth. The manufacture of the broach is complicated. Expensive, only suitable for high-volume production. Broaching is a finishing process. The precision is up to 1T7-9, and the surface roughness is Ra32~0.5 u m.
It is known from the above characteristics. The cutting fluid used for broaching, its main purpose is to protect the cutter and inhibit the built-up edge. Especially for inner hole broaching with a long cutting stroke, the cutting fluid can only be poured onto the broach before the broach is cut. Only a small amount of cutting fluid attached to the teeth acts throughout the cutting process. Generally considered. Internal surface broaching is the most demanding cutting process. For the above reasons. Broaching usually uses an oil-type cutting fluid with a strong adhesion and an extreme pressure agent. In recent years. Extreme pressure emulsions are also used for high speed broaching of the outer surface of certain free cutting materials.