LOW TORQUE TAP

摘要

A low torque tap (10) includes a shank portion (12) with a driving square (14) and a thread cutting portion (16). The thread cutting portion (16) includes a threaded body (20) with one or more asymmetrical straight flutes (22) that run essentially parallel to a longitudinal axis (L) of the tap. The thread cutting portion (16) also includes one or more short angular flutes (24) or spiral points and a tapered chamfer (28). For tapping steel alloys, the cutting edges of the straight flutes and the spiral points have a rake or chordal hook angle of between about 5 and 15 degrees. For tapping ferrous materials, the tap is made from molybdenum-enriched high-speed steel and may be coated with a wear-resistant, friction-reducing layer. A second, outer layer, such as molybdenum disulfide, may be applied over the wear-reducing layer for further reduction in friction. For tapping non-ferrous materials, the tap may be coated with a layer of material containing carbon.