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Broachingis a machining process that pushes or pulls a cutting tool (called a broach) over or through the surface being machined. Its high-production, metal-removal process is sometimes required to make one-of-a-kind parts. The concept of broaching as a legitimate machining process can be traced back to the early 1850s. Early broaching applications were cutting keyways in pulleys and gears. After World War 1, broaching contributed to the rifling of gun barrels. Advances in broaching machines and form grinding during the 1920s and 30s enabled tolerances to be tightened and broaching costs to become competitive with other machining processes. Today, almost every conceivable type of form and material can be broached. It represents a machining operation that, while known for many years, is still in its infancy. New uses for broaching are being devised every day.
Properly used, broaching can greatly increase productivity, hold tight
tolerance, and produce precision finishes. Tooling is the heart of broaching.
The broach tool's construction is unique for it combines rough, semi-finish,
and finish teeth in one tool (Figure 3).
There are two types of broaching procedures: internal broaching and external broaching. For exterior broaching, the broach tool may be pulled or pushed across a workpiece surface, or the surface may move across the tool. Internal broaching requires a starting hole or opening in the workpiece so the tool can be inserted. The tool, or workpiece, is then pushed or pulled to force the tool through the starter hole.
In conclusion, it may be said that the broach tool and the broaching process are versatile and important and that anyone who works in the field of metals, woods, or plastics should be familiar with them.
Hints for successfully broaching a keyway
1. Reverse workpiece or turn broach so teeth face toward the back of