Round Broaches vs Hexagon Broaches: Key Differences | Round Broach, Hexagon Broach

Among the standard internal broaching tools used across manufacturing, the round broach and the hexagon broach are two of the most common — yet they serve very different purposes based on the shape of the bore they are designed to cut. Understanding the differences between a round broach and a hexagon broach helps manufacturers select the correct tool for their component design.

A round broach is used to enlarge, resize, or finish a circular bore to a precise diameter and surface finish. While drilling or boring can create a round hole, these processes often leave a surface finish or tolerance that isn't accurate enough for precision applications. A round broach is passed through the pre-drilled hole to remove a small, controlled amount of material, bringing the bore to its final specified diameter with a smooth, accurate finish. Round broaches are commonly used in bushings, bearing housings, and any component where a precisely sized cylindrical bore is critical to proper fit and function.

A hexagon broach, by contrast, is designed to cut a six-sided (hexagonal) profile into a bore — rather than simply resizing a round hole, it fundamentally changes the shape of the opening from round to hexagonal. Hexagon broaches are used to produce internal hex features found in fasteners, fittings, couplings, and tooling components where a hexagonal socket or drive feature is required to engage with a matching hexagonal shaft, bolt head, or wrench. The graduated teeth of a hexagon broach progressively cut away material at the corners and flats of the hexagon until the final precise hex profile is achieved.

The key difference between the two, therefore, comes down to geometry and application. Round broaches maintain a circular cross-section and are used purely for sizing and finishing round bores, while hexagon broaches transform a round starting hole into a completely different geometric shape — the hexagon — used for torque-transmitting or drive-engagement features.

From a manufacturing standpoint, both tools follow the same fundamental broaching principle of graduated, progressively sized teeth, but hexagon broaches require more complex tooth geometry to accurately form the flats and corners of the hex shape, while round broaches have a comparatively simpler, purely cylindrical tooth progression. Both are typically manufactured from high-speed steel (HSS) for durability and precision, and both can be supplied as standalone tools or as part of a standard broach set.

Choosing between a round broach and a hexagon broach ultimately depends entirely on the required bore geometry for your component — there is no overlap in application, since one produces a round bore and the other produces a hexagonal one. Manufacturers producing components with both round and hex-bore features often require both tool types as part of their standard broaching toolkit.

Steelmans Broaches manufactures precision round broaches, hexagon broaches, and complete standard broach sets to meet a wide range of bore-profile requirements. To find the right tool for your component, visit Steelmans Broaches.