broaching

Broaching is a machining operation in which a long, toothed tool called a broach removes material from a workpiece to form a specific profile or hole. The cut is made in a single pass, as the broach advances through or across the workpiece, with successive teeth removing material to the final size.

Broaching can be internal, where the broach is pushed or pulled through a hole to shape its interior, or external, where the broach is drawn across a surface to create external features. A third form, rotary broaching, uses a rotary broach in a machine spindle to produce polygonal or curved profiles on a rotating workpiece or fixture.

Tooling and setup: A broach is a long tool ground with a sequence of teeth that progressively remove material toward the final size. The tool is mounted in a broaching machine, press, or CNC spindle, and material is removed as the work advances relative to the tool or the tool advances through the work. Internal broaching requires guiding bushings or fixtures to maintain alignment; external broaching relies on guides to control location and orientation.

Advantages and limitations: Broaching can produce precise sizes and smooth finishes for complex cross-sections in a single pass, making it highly productive for mass production. However, it requires specialized, costly tooling and machines with adequate stroke or rotary capability. It is generally economical when producing large quantities of identical parts and may be less suitable for low-volume work or deeply blind holes.

Applications: Broaching is used to create keyways, splines, dovetails, internal and external profiles, and polygonal holes in automotive, aerospace, hydraulic, and gear components, among other manufacturing sectors.