Gas turbine rotors have rotational speeds ranging approximately from 10,000 to 16,000 rpm, but in later years Rolls-Royce developed a two-shaft layout to improve efficiency, and subsequently a three-shaft concept for the RB211. These shafts run at different speeds. There is, of course, ancillary engine equipment operating at high rotational speeds. Naturally, bearing design and manufacture is of vital importance and must measure up to the exacting Rolls-Royce standards, so that the acceptance and use of outside suppliers’ bearings is a testimonial to the quality of the suppliers’ products.
Many of the rotor main bearings and ancillary equipment bearings in Rolls-Royce gas turbines are supplied by the Fafnir Bearings Co. Ltd., and by Ransome, Hoffman, Pollard, Ltd. the rollers and balls in these various types of bearing are located in the bearing cages, the material for which must possess certain physical and mechanical characteristics. It must have good anti-frictional properties to work well against hardened steel bearings under load; high fatigue strength and fine grain size; and high thermal conductivity to provide efficient heat dissipation.
One material which more than meets these requirements is Langley HIDUREL 5 (UNS C64711, DIN 2.0855, DTD 498). This is a copper-nickel-silicon alloy which has been supplied for many years to bearing manufacturers as ring stampings and forgings for bearing cages in bearings made for Rolls-Royce aero engines. Rolls-Royce superlative quality is just as meticulously maintain today as when the company was formed but the standards are even higher. So, the use of Langley material in its products is an endorsement of the skill and experience that goes into Langley alloys and component production.
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