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).
Review of excessive scrap in bearing production, detailing issues with various Hall's Aluminium-Tin alloys.
| Identifier | ExFiles\Box 115\3\ scan0065 | |
| Date | 30th September 1937 | |
| By.{R.W. Bailey - Chief Engineer} from Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell} c. Hs.{Lord Ernest Hives - Chair} c. RHC.{R. H. Coverley - Production Engineer} c. Hl. [Handwritten in red ink: 1020] Rm{William Robotham - Chief Engineer}/Swdl.{Len H. Swindell}10/AP.30.9.37 HALL'S ALUMINIUM-TIN ALLOY. In order to be of as much assistance as possible in regard to the excessive scrap which is at present experienced in the production ofthese bearings, we give herewith a review of the bearing position from our point of view. As we understand, the main reasons for this scrap are - (a) Inability to get the required Brinell hardness figure. (b) Porosity in the metal and often not detectable until the final machining operation. It has been pointed out that of the two alloys used, i.e. A.C.7. (Bentley and 25/30. big ends) and A.C.2. Bentley main bearings, the latter is the chief offender regarding the scrap obtained. Taking for example the A.C.7. alloy which has been used since the introduction of the 4¼ litre Bentley, we should like confirmation to the effect that the percentage scrap is no more at the present time than it was when first introduced. If this is not so and the fact is that the trouble has grown as time has gone on, every endeavour should be made to find out the reason i.e. whether the material as supplied from High Duty Alloys is faulty or some alteration in the process of casting is responsible. From the 175th chassis in K.{Mr Kilner} series Bentley, the A.C.2. alloy was introduced as the new main bearing material in order to overcome hammering out, hitherto experienced on the A.C.7. alloy. A.C.2. having a Brinell of 85 as compared with a figure of 45 obtained with the A.C.7. alloy. By virtue of a successful 17,000 miles run on 3.B.IV., whereby the A.C.2. main bearings had only increased over their original clearance figure by .001, we were committed to these for Production. Since this time the A.C.6. alloy has been introduced which we have found from our test bed results to be as satis-factory as A.C.2. with regard to non-hammering out and is more immune from picking up by reason of the increased tin element in its analysis. continued | ||