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 procurement, cost analysis, and manufacturing process for cylinder liners.
| Identifier | ExFiles\Box 132\4\ scan0041 | |
| Date | 4th January 1937 | |
| -2- The Sheepbridge Stokes Centrifugal Castings Co. at 3/8d. each for quantities of 2,500, and these can be machined in our own works up to the Nickel Deposit Stage in 1 hr. 45 Mins. each at a cost of 7/6d., which includes the necessary Heat Treatment, thus making the cost 11/2d. compared with 21/3d. now paid to the Sheepbridge Company for liners in this condition. This would result in a direct saving of 10/1d. per liner, or £6. 1. 0d. per set. We therefore recommend that commencing on D.{John DeLooze - Company Secretary} Series the castings only should be purchased from The Sheepbridge Company and the whole of the machining carried out in our own factory. Arrangements should be made whereby the first batch of 625 castings are delivered by March 25th and subsequent batches of the same quantity every four weeks. Will Roy{Sir Henry Royce}, please take the necessary action. During the machining process the Liners are heat treated in order to give the required Brinell figure of 400 to 450 as follows - (a) Heat up to 845°C. for approx. 10 mins. and quench in oil. (b) Temper in salt bath at 250°C. to 260°C. For the quenching operation, Houghton's No.2 Quenching Oil is used, and is supplied by Messrs. Edgar Vaughan & Co. Ltd., of Birmingham. Further investigations are being carried out on alternative materials, and should any satisfactory results be obtained on suitable irons in the region of 250 Brinell, further reductions in the cost can be anticipated, as higher cutting speeds will be obtained, and less grinding necessary, in addition to the saving on heat treatment. In addition the Design Dept. are proceeding with the scheme of fitting a small diameter rubber at the top spigot of the liner, so that these can be ground in the bore, thus eliminating the two honing operations as is the present practice. This, it is estimated will save an additional 4/- per chassis. RHC.{R. H. Coverley - Production Engineer} | ||