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).
Considerations for the design, profitability, quantity, and quality control of forged parts.
| Identifier | ExFiles\Box 148\5\ scan0384 | |
| Date | 20th July 1938 | |
| -5- ROY{Sir Henry Royce}/Les.1/B.20.7.38. 3. Design of forging (Contd:- (a) Weight of part (b) Weight of hammer necessary (c) Suitable material for changes in cross-section (d) Number of changes in cross-section (e) Percentage of maximum to minimum of cross-section (f) Wear and cost of tools. All this is provided the firm has suitable equipment. 4. Percentage of profit. As long as we call for expensive material and complicated forgings, we cannot expect forging firms to quote a really economical price for their work. It is always difficult for a forging firm to quote accurately as they have no similar parts going through their production. We do not think there are many firms making a very excessive profit from our forgings, as there is in many cases increased forgers' overhead charges due to the progressing of our special materials and certain difficulties in design. 5. Quantity. For straightforward large forgings a reduction of 3 in the cost can be made by increasing the quantity from 500 to 1,000 parts. The difference in cost for quantities can be very misleading because certain firms spread part of the tool cost over the complete order. In future we hope to pay for the complete tools separately so that we are in a position to know the correct price for repeat orders. We shall then investigate difference in price due to far greater variations in quantity. 6. Quality. As the forging cost in some cases is only 15% of the cost of the fully machined piece, it is necessary to keep the quantity of faulty forgings as low as possible. It is, however, intended to get in touch with firms which have supplied inferior quality forgings at a low price and see if it is possible to improve their quality. With a simple forging the essential requirements are - (a) Correct alignment of dies (b) Avoidance of cracks and folds (c) Consistency of forging thickness (Contd:- | ||