For cutting external threads according to the ISO standards of metric coarse threads M1 to M68 and metric fine threads M1 to M56 preslotted (Form B) round dies are used. Round dies with an outer diameter of d = 16 mm or d = 20 mm have three chip holes. Larger sizes have four or more chip holes. The round dies can be used from both sides as the cutting parts are on both sides.
The guides are fastened together with the round dies in the round die holder. The guide tube has exactly the same diameter as the bolt on which the thread is going to be cut. Therefore the cutting runs plump-line and the flanks are cut accurately. The round die guides are made from aluminium and produced in the die-casting process. They have chip holes such as round dies to take away the chippings.
Hexagonal die nuts are used for assembling work and for recutting threads with medium tensile strength. The standardized key sizes of the hexagon allow the use of ring spanners or jaw spanners as tool holders. The hexagonal surfaces are abrasion-proof and burnished corrosion protected.