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).
Casting issues with iron liners in aluminium brake drums and a suggested test program.
| Identifier | ExFiles\Box 120\1\ scan0297 | |
| Date | 3rd February 1941 | |
| To Rm.{William Robotham - Chief Engineer} from Rm{William Robotham - Chief Engineer}/GB. Cc. Rm{William Robotham - Chief Engineer}/MHR.{M. H. Rigby} ALUMINIUM BRAKE DRUMS (RR.53). Two iron liners have been cast in aluminium drums One drum split round the face whilst cooling. The second drum was left in the mould overnight and is now being machined. Messrs. Roberts & Thompson of the Foundry think that splitting would be avoided if the drums were left in the mould for about two hours after casting. The split drum was cut to pieces for inspection. The liner was not bonded to the drum except at a few small spots. For best results it would seem to be desirable to get a good bond between liner and drum. The adjoining surfaces of liner and drum were clean enough to provide good electrical contact, so that heat conductivity should be satisfactory. When casting, the core supports the liner in the mould. The core is made of Southport sea sand and a binder. The liner is placed on the core and the two are heated together in an oven. The oven temperature determines how much of the binding material is evaporated out of the core. Oven temperature is regulated so that there is just enough strength left in the core to enable the casting to be made. The temperature for the drum core was 230° C. When binder condensate settles on the liner, a bond with the aluminium is impossible. The drum core was placed at the bottom of the oven so that the condensate would rise away from it. Chilling by the liner will also prevent a bond being obtained. The following programme is suggested:- 1. Get a second drum cast and machined so that we can put a pair on a car. The liner for the second drum is already machined. A comparison can then be made between standard and aluminium drum temperatures and crackling noises listened for. | ||