2016 Volume 11 Issue 2 Pages 81-87
To extend tool service life, several types of tapping tool coated with hard films have recently been developed. However, the detachment of films from tool surfaces and chip snarling on tools remain barriers to further increases in tap service life and tapping speed. In this study, a tapping tool coated with a composite film composed of nickel-phosphorus (Ni-P)/silicon carbide (SiC) particles was developed, and its machining performance was experimentally investigated. The composite film was coated on a spiral tap using electroless plating. Tapping tests demonstrated that the new tapping tool prevented chip snarling at five times the conventional cutting velocity. At such high velocities, chip snarling occurred on other taps, including one with a conventional steam-treated surface, one coated with a titanium carbo-nitride film and one coated with Ni-P plating taps. Furthermore, due to its high resistance to wear, the tool service life of the tapping tool coated with the composite film was approximately two times longer than that of the conventional steam-treated tapping tool. These results indicate that the tapping tool coated with the Ni-P/SiC composite film has the ability to increase processing efficiency and extend tool service life.