From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Analysis of roller faults relating to core hardness, material structure, and casehardening depth.
| Identifier | ExFiles\Box 153\1\ scan0238 | |
| Date | 3rd April 1939 | |
| -3- The outstanding fault is that the core of the rollers is much too hard, and, consequently, brittle. The core should be 400-450 brinell. Core hardnesses we have measured on faulty rollers vary from 550 to 660 brinell. Owing to the production need of satisfactory rollers, we have broken only one for examination. This had a core hardness of 440 brinell. The structure of the case material is in many instances very poor, and appears to indicate over-heating of the steel during heat-treatment. Material analyses are not yet complete, but so far indicate that at least two different kinds of steel have been used. The casehardening is in many instances too deep, with the result that the size of the core is reduced. We do not yet know the maximum load capacity that can be obtained from the rollers when the material and its condition are correct. This may be appreciably more than 100% overload. Rm{William Robotham - Chief Engineer}/FJH.{Fred J. Hardy - Chief Dev. Engineer} | ||