Machine taps with coloured ring: the material at a glance
With the coloured-ring machine taps, the ring on the shank takes over the material assignment. Instead of comparing material, coating and chamfer one by one, you pick the matching colour: green ring for unalloyed steels, blue ring for tough and alloyed steels, white ring for stainless steels, black ring for grey cast iron, yellow ring for aluminium, orange ring for brass and red ring for high-strength materials.
Machine Tap RED RING DIN 371 Form C 15° Spiral Flute HSSE-PM TiALN - M 5 x 0.8
Machine Tap RED RING DIN 371 Form C 15° Spiral Flute HSSE-PM TiALN - M 6 x 1.0
Machine Tap RED RING DIN 371 Form C 15° Spiral Flute HSSE-PM TiALN - M 8 x 1.25
Machine Tap RED RING DIN 376 Form C 15° Spiral Flute HSSE-PM TiALN - M 12 x 1.75
Machine Tap RED RING DIN 376 Form C 15° Spiral Flute HSSE-PM TiALN - M 14 x 2.0
Machine Tap RED RING DIN 376 Form C 15° Spiral Flute HSSE-PM TiALN - M 16 x 2.0
Which ring colour for which material?
- Green ring: unalloyed steels up to 1,000 N/mm², malleable cast iron and thermoplastics. The all-rounder for structural and free-cutting steel.
- Green ring PM: powder-metallurgical HSSE-PM with TiN coating for stainless, alloyed and unalloyed steels as well as copper and aluminium alloys, when one tool should cover as many materials as possible.
- Blue ring: high-alloy, tough and stainless steels and alloyed tool steels up to 1,200 N/mm². The TiCN coating at 3,000 HV is particularly wear-resistant.
- White ring: stainless steels and high-alloy chromium steels, long-chipping materials up to 1,000 N/mm².
- Black ring: grey cast iron, magnesium alloys and nitrided surfaces, for through and blind holes.
- Yellow ring: aluminium and other long-chipping materials, two-fluted for blind holes.
- Orange ring: brass and short-chipping materials.
- Red ring: difficult-to-machine materials above 1,200 N/mm², HSSE-PM with TiAlN coating.
Cutting speed and lubrication
Guide values range from 2 to 4 m/min for high-strength and stainless steels, 10 to 18 m/min for unalloyed steels, up to 20 to 30 m/min for aluminium and magnesium. Tapping oil or emulsion is recommended for steel, a cutting oil for non-ferrous metals for those materials. The complete table comes with every tool as technical information.
From practice
Two field tests show how the rings perform: the green ring in 42CrMo4 and the black ring in a GG25 cylinder block. All coloured-ring taps are also available as a TwinBox with matching twist drill under tap and die sets. If you want to make the material assignment yourself, the full range is under machine taps.
