High Speed Tool Bits
Crucible carries high speed tool bits in Rex 95 (T8), Rex AAA (T4), CPM Rex T15 (T15) and CPM Rex 76 (M48), in various squares flats and rounds. Crucible Rex high speed tool bits are surface ground after heat treatment to close dimensional tolerances. Rex AAA tool bits are also available in a “metallisized” finish. The metallisized bits are manufactured from close-dimensional pre-ground bar stock and are metallic grit blasted after heat treatment, producing a clean, smooth, metallic finish with size tolerance superior to hot rolled tool bits.

Nominal Analysis, %
T8 T4 T15 M48

Carbon 0.80 0.75 1.60 1.50
Manganese 0.30 0.30 0.30 0.30
Silicon 0.30 0.30 0.30 0.30
Chromium 4.00 4.00 4.00 3.75
Vanadium 2.00 1.15 4.90 3.10
Tungsten 14.00 18.00 12.00 9.75
Molybdenum 0.75 0.75 5.25
Cobalt 5.25 5.00 5.00 8.50

CPM REX 76 (M48) is a super high speed steel made by the Crucible Particle Metallurgy Process. It has notably high carbon, vanadium, and cobalt for abrasion resistance equal to T15 and superior red hardness. CPM REX 76 is heat treatable to HRC 70. Its high hardness, fine grain size and uniform carbide distribution make it outstanding for special purpose cutting tools beyond the capabilities of the AISI Type M40 series high speed steels. The best applications are where high red hardness, high abrasion resistance, and good toughness can be used to advantage.
    REX AAA (T4), with its 5 percent cobalt content, is a high speed steel with a balance of good toughness and good red hardness. REX AAA is recommended for general purpose applications and as a substitute for REX AA.
    REX 95 (T8), is a tungsten-vanadium-cobalt high speed steel developed to meet the requirements for a tool bit combining high red hardness, superior abrasion resistance but with slightly less toughness than REX AA or the molybdenum types.
    CPM REX T15 (T15), is a tungsten type high speed steel containing high carbon and vanadium for very high hardness and maximum wear resistance, and cobalt for good red hardness. It is now made exclusively by Crucible’s Particle Metallurgy process resulting in improved quality and a grindability ratio over 3 1/2 times that of conventional T15. CPM REX T15 was designed for use in machining operations requiring heavy cuts, high speeds and feeds, and for difficult to machine materials that are high in hardness and abrasion resistance.
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