Round dies for external threads
Dies cut external threads on bolts, shafts and pipes, by hand in a die holder or on the machine. VÖLKEL supplies around 1,600 versions: round dies to DIN 223 (DIN EN 22568) in HSS, HSSE and HSSE-VAP, dies for brass, square dies and hexagon die nuts to DIN 382. They cover metric coarse and fine threads, BSW, BSF, BA, UNC, UNF, UNEF, 8-UN, pipe threads G, R, Rp and NPT, PG, cycle thread BSC and left-hand threads.
Form A or form B, HSS or HSSE
Round dies come slotted (form A) and closed (form B). The slotted form can be adjusted slightly via the retaining screws, the closed form is stiffer and more accurate; VÖLKEL supplies all dies in form B unless stated otherwise. The spiral point chamfer gives a clean thread start.
HSS covers unalloyed steels up to about 800 N/mm², cast iron and non-ferrous metals. HSSE is the choice for alloyed, stainless and tough steels. HSSE-VAP (version VX) holds the lubricant film better thanks to its vapour-treated surface and suits long-chipping materials. For brass there are dedicated dies (version MS) with adapted cutting geometry.
Hexagon die nuts
Hexagon die nuts to DIN 382 are turned with an open-end spanner. They are meant for recutting and repairing damaged threads and for places where no die holder fits. For cutting new threads the round die remains the more accurate tool.
Square dies
Square dies run in their own holders and mainly cover larger threads and special cases.
Holder, bolt diameter, lubrication
The outside diameter of the die (16 x 5 mm to 160 x 25 mm) determines the die holder. The bolt should be slightly below nominal diameter; the values are in the technical information on bolt diameters. How to get a clean thread by hand is shown in Cut external threads cleanly by hand using a die; for squarely started threads use die guides. Complete sets with hand taps are under tap and die sets.
