Roughers for Hardened Materials - Series 103 Series 103 Roughing End Mill for Hardened Materials. View Speeds and Feeds page. Features: Designed for use on extremely tough to machine materials with a 60+Rc hardness and high temperature alloys. 20 Degree Helix 4 Flute Corner Radius standard to strengthen end teeth Available with nACRo® (Part Number ends in 5) and AlTiN (Part Number ends in 4) coatings