For milling cutter end mill

Flutes: More flutes allows a higher feed rate, because there is less material removed per flute. But because the core diameter increases, there is less room for swarf, so a balance must be chosen.

Coating: Coatings, such as titanium nitride, also increase initial cost but reduce wear and increase tool life. TiAlN coating reduces sticking of aluminium to the tool, reducing and sometimes eliminating need for lubrication.

Helix angle: High helix angles are typically best for soft metals, and low helix angles for hard or tough metals.