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).
Investigation into the magnesium content and casting process of AC.9 bearing material.
| Identifier | ExFiles\Box 115\5\ scan0146 | |
| Date | 17th October 1938 guessed | |
| COPY. re AC.9 BEARING MATERIAL Mr. Richards of High Duty Alloys arrived at the Works on Monday morning at about 11.30 a.m. with the object of looking more closely into what we are doing in connection with AC.9 bearings. He confirmed the message that we had received over the 'phone from Mr. Robinson that bearings which we had sent to H.D.A. for examination were low in Magnesium content, this being .55%, these bearings being from batch 1, Melt 21 material. Our own figures of Magnesium content were within specification, and we have counterchecked our figures to make quite sure that there is no error, and therefore it became one of the points to investigate, to see whether it was possible for variation to take place between the beginning and end of casting from material, or variation due to the pot as work progressed. Accordingly one of the melting pots was emptied and thoroughly cleaned out on Mr. Richards' arrival, and a melt of AC.9 material was used, the actual ingots being batch 2, Melt 23, two dies being used to produce bearings, one producing a half bearing, and the other a bush for the Napier job. Bearings were cast from the pot in the ordinary way, by the usual method, and usual temperature, so that Mr. Richards could get a full insight as to exactly what we are doing, and have been doing since we started on this job. After completing a number of bearings from the first die, and at the same time naturally lowering the amount of material in the pot, the die was changed to a Napier bush, and casting continued. After a number of casts with this, as the material was getting lower in the pot the original die was put back into operation and all the material in the pot worked out. Bearings from these various casts have been taken by Mr. Richards so that he has the 12th and we have the 11th bearing, and so on through the job, to see whether, during the progress of casting and fluxing of the material | ||