A1-303-20

2 and 3 flute high-performance aluminum end mills — the stub-length A1-201 cuts the horsepower a cut demands, and the polished Mirror Edge A1-303 is the chatter-killer a defense manufacturer called 'the only tool that could make the part.'

• Two geometries: A1-201 2-flute stub length (30° helix) designed to reduce required horsepower, and A1-303 3-flute standard length (35° helix) with Mirror Edge and polished flutes for chatter reduction
• Inch sizes 1/8"–1" cutting diameter; metric MA1 line runs 3–20 mm in both 201 and 303 geometries
• Corner break (chamfer) on every size — .005 on 1/8"–5/16", .010 on 3/8"–3/4", .015 on 1" (MA1: 0.1–0.3 mm)
• Guide-published speeds & feeds run at Max RPM in aluminum 6061/7075/2024 with chip loads scaling from .0032 (1/8") to .0160 (1") per tooth
• Axial depth of cut up to 1.5 × diameter with 50% radial step-over per the guide's A1 speeds & feeds pages
• Applications: slotting, side milling, helical interpolation, ramping, high-performance roughing, semi-finishing, and finishing; A1-201 runs dry, wet, cold air, or spray mist (A1-303: wet)
• Materials: aluminum, copper, magnesium, brass — plus plastics on the 2-flute A1-201
• Available uncoated or Diamond-Like Carbon (DLC) coated on every size
• Guide case story: in deep-pocket/thin-wall aluminum at a major defense manufacturer, the A1-303 was the only tool that could make the part — 8 other high-performance tools tried and failed (6 broke, 2 loaded up with aluminum)
• h4 shank tolerance — up to 150% more gripping force to eliminate tool pull-out ('tightest in the industry'); A1 tolerances: cutting dia −.0007/−.0015, shank −.0001/−.0002, flute length +.060/−.000

From the RobbJack Applications Guide.