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).
Cracking of Wraith cylinder blocks after heat treatment and analysis of the material.
| Identifier | ExFiles\Box 8\6\ 06-page48 | |
| Date | 2nd November 1938 | |
| 619. By.{R.W. Bailey - Chief Engineer} c to Rn.{Mr Robinson} c to HEC. RHC{R. H. Coverley - Production Engineer}/Vs.{J. Vickers}1/JT.2.11.38. Iron Foundry. Wraith Cylinder Blocks. In reply to your memo By.S/C.27.10.38 regarding cracking of cylinder blocks after heat treatment, we would emphasize that all blocks pass a water test of 75 lbs/sq. ins. before leaving the foundry, and we have so far never encountered a cracked casting at this stage. This seems to clearly indicate that the cracking occurs during the heat treatment process, and we do not consider the presence of white iron in itself responsible for cracks providing the stress release treatment is carried out in a proper manner. There are in fact various chilled castings in regular use having white and grey iron in juxtaposition such as tappets, camshafts, etc., on which cracking is not generally encountered. With regard to the analysis of this cylinder block material, we would draw your attention to the modified specification No. 212A which was drawn up and sent to you under memo' reference RHC.{R. H. Coverley - Production Engineer}1/LS.31.12.37. This varied slightly from the former specification No. 212A dated August 1925, and was merely a confirmation of the composition in actual use when the foundry came under the writer's control. No Chromium is actually added to the cylinder blocks, and that revealed by the analysis of the cylinder block must therefore be due to a slight contamination in return foundry scrap, and at no time have we departed from the standard specification. RHC{R. H. Coverley - Production Engineer}/Vs.{J. Vickers} Hickins | ||