Click Image to Enlarge
The special geometry of this end mill creates stability in the cut because each tooth is removing small amounts of material, thereby reducing tool pressure, shock effects and harmonic vibration. The optional coolant groove leads coolant along the helix angle and into the cutting zone.
When the companies that make razor blades put two cutting edges in one cartridge, they changed the nature of removing whiskers forever. The developers of the Raptor dual-tooth fluted end mill like to point out this fact when introducing their unusual line of cutting tools.
The concept is simple. Frank and Guy Calamia, two brothers who own Destiny Tool (Santa Clara, California), looked at the conventional solid carbide end mill with two or more cutting teeth that spiral along the periphery of the tool shank. Guy Calamia, the inventor, reasoned that adding a second, closely-spaced cutting tooth to the normal ones would radically alter the performance of such an end mill—much the way the second blade on the razor altered the experience of shaving. The end result is a line of end mills such as the one pictured on this page. These “Raptor” end mills feature three flutes with six teeth, four flutes with eight teeth or five flutes with ten teeth.
This geometry creates an end mill that provides extended tool life, low vibration, high feed rates and fine surface finish. Tool life is extended because the cutting edge of the second, trailing tooth remains relatively sharp as the leading tooth wears. Cutter life also benefits from the low level of vibration that occurs during cutting. Because two closely spaced cutting teeth creates an irregular pattern of tooth-to-workpiece contact, the harmonics that contribute to unwanted vibration (chatter) are greatly diminished. Varying the helix angle from tooth set to tooth set likewise helps control vibration.
Doubling the cutting edges means that feed rates can be proportionately increased because chip load per tooth is reduced. (The chip load on the second tooth in each set is actually lower than on the first, however, and the size of the chip cut by this second edge is smaller, too.) Low vibration and cutting edges that remain sharp longer contribute to a fine surface finish.
End mills in the line are available with optional coolant grooves that spiral at the same helix angle along the periphery of the shank. These grooves allow coolant fed through the spindle to run down the grooves and penetrate the cutting zone for improved cooling and chip removal.
The end mills, which are currently available from 0.25 to 1.0 inch in diameter, are coated with AlTiN for ferrous applications in a profiling or finishing operation. According to the developers, prices for the Raptor end mills are similar to comparable conventional solid carbide cutting tools.