A slotting machine is like a vertical shaper: a ram moves a single-point tool up and down while the work, clamped on a rotary table, is fed into it. It cuts internal keyways, splines, square holes and slots, including blind ones, in pulleys, gears and couplings. It is slower than broaching but needs no special tooling.
Quick facts
- Motion
- Vertical reciprocating ram
- Typical stroke
- About 100–300 mm (3.94–11.81 inch)
- Table
- Rotary, with cross and longitudinal travel
- Tools
- Simple single-point slotting tools
- Typical work
- Keyways, splines, internal slots, square holes
- Drive
- Mechanical or hydraulic
Slotting or broaching?
| Slotting | Broaching | |
|---|---|---|
| Speed | Slow | Very fast |
| Tooling cost | Very low | Broach per size |
| Blind keyways | Yes | No |
| Best for | One-off and odd sizes | Batches of standard sizes |
Good to know
- The rotary table indexes for splines and multiple slots
- Ram stroke limits the deepest bore
- CNC keyseaters and wire-cut EDM are modern alternatives
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Questions
- Slotting machine or shaper?
- A slotter's ram moves vertically and is used for internal work; a shaper's ram moves horizontally for external flat surfaces and slots.
- Can a slotter cut a blind keyway?
- Yes, as long as there is room for the tool to stop at the end of the stroke.
- Is slotting accurate?
- Good enough for standard keyways; precise splines are usually broached, hobbed or wire cut.
The figures on this page are typical values for guidance, written by Diemeco from standard engineering practice. They are not a specification: confirm grades and properties with the relevant standard or the supplier's mill test certificate, and tolerances with your workshop. Last checked 23 October 2026.