Micro end mills from LMT have differing helix angles

The DHC series is ground with two different helix angles of 35° and 38° on consecutive flutes and feature through coolant feed. Successive differences in the helix angle from tip to tip, creates a continuously changing pitch to the cutting edge, reduces cutting forces and creates chips with different cross-sectional areas. As a result, any tendency for vibration to build up that can lead to poor surface finish and pre-mature failure is reduced, especially when milling difficult materials. On a recent cutting trial performing a slotting operation in heat treated steel, a 2 mm diameter DHC 1521C long series cutter, with four flutes, was run at 18,000 rpm with 2 mm depth of cut and 0.01 mm/min feed per tooth. The DHC 1521C and 1522C end mills are available in diameters between 1 mm and 20 mm in straight shank style. The 1 mm diameter cutter has a 0.025 mm by 45 deg chamfer that provides edge protection, this is progressively increased across the range to 0.3 mm on the largest 20 mm tool.