4/2 Flute Flat End Mill

The 4/2 Flute Flat End Mill is a square-end milling cutter supplied with two or four flutes, intended for flat-bottom milling, slotting, shoulder milling and profile work. The standard range covers 38 sizes with cutting diameters from 1 mm to 20 mm and overall lengths of 50, 60, 75, 100 and 150 mm, including seven sizes built on a shank larger than the cutting diameter for extra rigidity. Four grade series are offered — HRC55/56, HRC60, HRC65 and S5 — and each series is supplied with its own coating finish, as shown in the product photos. Flute count and grade series are confirmed against the workpiece when the order is placed. Extended-length sizes reach deeper pockets, shoulders and bores where a standard-length cutter cannot follow.

Each size is written in one line, for example D6*15*D6*50L, where the four numbers are the cutting diameter (d), the flute length (l), the shank diameter (D) and the overall length (L), all in millimetres. The flute count is not part of the code, so it has to be stated separately, and it is the only figure that changes between a two-flute and a four-flute version of the same size.

The flute count changes how the cutter behaves. A two-flute end mill leaves more room in each flute for chip evacuation; a four-flute end mill puts more edges into one revolution, which generally helps wall finish at the same feed. Where the work is limited by chip clearance, two flutes are the usual choice; where wall finish and removal rate matter more, four flutes are. Because the right series and flute count depend on what is being cut, we confirm both against the workpiece material and operation rather than publish a fixed recommendation table.