Double Keyway Rotary Broach Tool

Keyway Rotary BroachRotary broaching is ideal for machining very accurate forms with a short length, small amount of material removal and balanced shape. This includes double keyways. Spline shapes often resemble keyways but have more teeth.

Rotary broaching does have various limitations that need to be considered before selecting a broach for making keyways. For example, rotary broaching relies on the helical motion of the cutting tool, and single keyways tend to interrupt the flow of that motion. Most testing with single keyways has resulted in the broach breaking before reaching finished depth.

Double keyways have much better test results and can often be substituted for forms that require a single keyway. The second key way is simply used for manufacturing purposes and not for use in the design of the part. Cutting more keyways is also an option, but will increase pressure during the broaching operation.

Material removal is also an important factor. Although the width of the key is important, more often the depth of cut required is the critical factor. The depth of cut is determined by subtracting the minor diameter from the major diameter, and dividing that in half.

Depth of cut for most forms is limited to about .025” per side. If the form is larger, rotary broaching may not be the best machining option. Conventional broaching, EDM, or single point shaping may be alternative solutions.

Part preparation for double keyways is the same as any other form. The opening of the hole must be chamfered at least to the major diameter (or larger). The pilot hole should be slightly oversize to accommodate the body of the broach. There must be room at the bottom of the hole for chips.

Quotes can be provided for double keyway rotary broaches with minimal information. It is best to supply part material, depth of form, major and minor diameter and keyway dimensions. Other information such as pilot hole depth, machine type and number of parts to make are helpful but not required.

To request a quote on a Double Keyway Rotary Broach fill out our online quote form or call us at 239-628-4800.

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