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).
The distortion of aluminium brake shoes after two stages of heat treatment.
| Identifier | ExFiles\Box 30\6\ Scan223 | |
| Date | 19th October 1933 | |
| To Hs{Lord Ernest Hives - Chair}/Gry.{Shadwell Grylls} from RHC.{R. H. Coverley - Production Engineer} Handwritten notes: X1559, GRY{Shadwell Grylls}, See me, HS{Lord Ernest Hives - Chair}, 87 ALUMINIUM BRAKE SHOES After taking accurate measurements of the principle dimensions, a Phantom brake shoe G.79090 was handed to Hl. for heat-treatment in accordance with your Hs{Lord Ernest Hives - Chair}/Gry{Shadwell Grylls}8/KT.27.9.33. The heat-treatment was carried out in two stages of 16 hrs. at 220°C and 16 hrs. at 300°C. further measurements being made at the end of each period. The amount of distortion due to the heat treatment was found to be as follows:- Heat treatment Table: Heat treatment: After 16 Hrs.@ 220°C Total Distortion - Measured on: A: +.008, B: +.002, C: +.002, D: +.005, E: +.017, F: 0, G: -.001, H: -.002 Heat treatment: After 16 Hrs @ 300°C Total Distortion - Measured on: A: +.008, B: +.002, C: +.002, D: +.005, E: +.017, F: +.002, G: +.002, H: 0 As will be seen from the above figures, most of the distortion took place during the first stage of the heat treatment. It would therefore appear that a low temperature heat treatment of say 12 hrs. at 170°C. prior to machining, should eliminate any tendency to distort due to over-heating in service. RHC.{R. H. Coverley - Production Engineer} | ||