Machine taps for every type of hole
Machine taps cut the internal thread in one pass on a drilling machine, machining centre or lathe. VÖLKEL supplies around 1,900 versions to DIN 371, DIN 374 and DIN 376 as well as ISO 529 and JIS B 4430: for metric coarse and fine threads, UNC, UNF, UNEF, BSW, BSF, pipe threads G, Rc, Rp and NPT, round threads Rd, cycle threads BSC and left-hand threads. Materials are HSS-G, HSSE and HSSE-PM, optionally with VAP, TiN, TiCN or TiAlN treatment.
Chamfer form: through hole or blind hole
The chamfer decides where the chips go. Form B has a spiral point chamfer of 4 to 5 threads and pushes the chips forward out of the hole; it is the choice for all through holes. Form C with a 2 to 3 thread chamfer and right-hand spiral flutes (15°, 35° or 40°) draws the chips back and is meant for blind holes. Form A with 6 to 8 threads suits short through holes, form B-AZ with interrupted threads suits tough, long-chipping materials. The basic decision is explained in Form B or form C.
Standard and shank
DIN 371 applies up to M 10 with a reinforced shank, DIN 376 from M 12 with an overflow shank, DIN 374 covers the fine threads. Extra-long versions serve deep reaches, combination taps with round shank and square drive serve special cases.
Material and coating
HSS-G covers structural steels, cast iron and non-ferrous metals. HSSE is the choice for stainless and alloyed steels, HSSE-PM for high-strength materials. VAP improves lubricant adhesion, TiN and TiAlN raise hardness and cutting speed, TiCN at 3,000 HV is the hardest coating for abrasive materials. See Coatings at a glance. If you prefer not to make the material assignment yourself, use the machine taps with coloured ring, where the ring colour indicates the material group.
Tolerance and tapping drill
The standard tolerance is ISO 2 (6H). For coated workpieces or more clearance there are 6G, 7G, +0.1 mm and 4H, explained in Thread tap tolerances at a glance. The tapping drill size for every thread is in the tap drill table. Matching sets with twist drills are under machine tap sets.
