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).
Comparing the costs of manufacturing a sump using die-cast aluminium versus pressed steel.
| Identifier | ExFiles\Box 111\2\ scan0248 | |
| Date | 28th September 1937 | |
| S E C R E T To By.{R.W. Bailey - Chief Engineer} from RM{William Robotham - Chief Engineer}/sd. c.c. Hs.{Lord Ernest Hives - Chair} c.c. AWO/sd. c.c. DM{D. Munro}/Jmr. File 1044 850 PHOENIX SUMP. In reply to memo AWO/SB.{Mr Bull/Mr Bannister}1/L2.1.9.37. it would appear to us that the matter is not as simple as the above memo would tend to make out. Amongst other things we have to take into account the possibility of simplifying the design to adapt it to our own machinery, the cost of preliminary work on the aluminium before casting, the higher percentage of scrap in casting as against pressing, machining costs in one case and welding costs in the other. The fact that horizontal baffles may be required, which would make die-casting impossible as the die could not be removed, and various other points. It is proposed to deal with these points as under:- (1) Material costs. The aluminium alloy suggested for this job by RMC costs about 6d. per lb., which assuming the simplified design of sump to weigh 12lb. would give a material cost of 6/- per sump. If we now assume a pressed steel sump to weigh 10lbs., then in black sheet steel, it would cost approximately 2/- for material. (2) Manufacturing Costs. Taking a very approximate tabular analysis of costs as below, we see that for 1000 sumps a direct comparison shows a 10% gain for a pressed steel sump. Die-casting:- Melting and Pouring. £0. 1. 0. Tooling Costs. (Dies at £150) £0. 3. 0. Material Costs (Alloy 6d per lb.) £0. 6. 0. Machining Costs. £0. 1. 6. _________ Total. £0. 11. 6. | ||