Broaching is the process of removing material by pulling or pushing a cutting tool, called a broach (sometimes called a broach cutting tool), through or past a piece part. The teeth on the broach are equally spaced, with each tooth successively larger, and more to the shape desired, than the previous tooth. Each tooth usually removes only a few thousandths of an inch of material, until finally the part is the exact shape and size desired.

What shapes and forms can be cut using the process?

The most common type can be seen when cutting an internal keyway in a gear or pulley. Likewise, many common shapes, such as squares and other polygons can easily be formed using the process. Broaching is also used to cut internal splines, either straight-sided or involute, in hubs, gears, and sprockets. However, broaching can be used to cut virtually any shape or form, and is limited only by the length and width of the shape to be undertaken. Although it is most commonly used to cut internal shapes and forms, external broaching is also used to cut slots and other external shapes.

What materials are suitable for the process?

Broaching can be used to cut any material that can be machined using traditional machining operations, such as milling. Therefore, broaching is highly suitable for all ferrous and non-ferrous metals, including alloys and castings, as well as many types of plastics.

I only have a few pieces. Is broaching a suitable operation?

That depends. Quality broaching services maintain an extensive inventory of stock broaches. This inventory typically includes multiple sizes and lengths of keyway broaches, square hole broaches, hex hole broaches, D hole broaches, involute spline broaches, straight-sided spline broaches, and many more standard and specialty broaches. If they have an inventory broach that is suitable for your job, there should be no additional cost for the use of that tool. Therefore, broaching can be an extremely cost-effective means of machining just a few pieces.

How does broaching compare with other types of machining operations?

Broaching competes very favorably with traditional machining operations, such as milling, both for small runs using stock broaches, and large runs using custom-designed broach tooling. In many cases broaching is literally the only way to cut internal straight-sided forms and shapes.

What is the measure of a good broaching company?

Besides the typical ways to assess the quality of a machine shop, such as quality control and customer service, a good broaching company must also possess the following attributes:

• Maintain a large and diverse inventory of stock broaches, available to customers for use on their parts at no additional charge.
• Have the ability to make their own tooling, as well as sharpen and recondition it, in-house. Ideally, they will have a department devoted entirely to broach manufacturing, sharpening, and reconditioning. This allows for faster turnaround on customers' parts, and the ability to make changes and adjustments to tooling as needed, for optimum efficiency.
• Possess a wide range of equipment to accommodate any broaching challenge: virtually any size, shape, and quantity of parts.