Picking an end mill comes down to three choices: how many flutes, what shape, and which coating. Match those to your material and operation and most feeds-and-speeds problems solve themselves.
Flute count
| Flutes | Best use |
|---|---|
| 2 flute | Aluminum and plastics; maximum chip clearance, good for slotting |
| 3 flute | Aluminum with a better finish while still clearing chips |
| 4 flute | Steel and stainless; more cutting edges, better finish and rigidity |
| 5–6+ flute | Finishing passes and hard materials with light radial cuts |
End mill type
| Type | Use |
|---|---|
| Square end | General milling, slots, shoulders, flat floors |
| Ball nose | 3D contouring, fillets, curved surfaces |
| Corner radius (bull nose) | Tougher edge for roughing and semi-finish; avoids chipping |
| Roughing (hog) | Fast stock removal; serrated edge breaks chips |
| Chamfer | Edge breaks, deburring, countersinks |
Suggested setup by material
| Material | Suggested tool |
|---|---|
| Aluminum | 2–3 flute, uncoated or ZrN, high helix (35–45°) |
| Mild steel | 4 flute, TiAlN, ~30° helix, flood coolant |
| Stainless | 4–5 flute, TiAlN or AlTiN, variable helix, rigid setup |
| Titanium | Low helix, AlTiN, light radial cuts, very rigid setup |
| Plastics | 2 flute, uncoated, polished flutes, high RPM |
More flutes give a better finish but less chip room; softer, gummier materials need fewer flutes so chips can escape.
Pair this with the Tool Coating Comparison and the Feeds and Speeds Chart.