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).
Machining austenitic steels, detailing improvements to boring processes using reamers and 'D' bits.
| Identifier | ExFiles\Box 96\2\ scan0081 | |
| Date | 27th November 1935 guessed | |
| 2. Austenitic steels are difficult to machine particularly where boring processes are concerned owing to the fact that the material tears so very easily, and the scoring which takes place necessitates polishing. Improvement can only be effected by using a reamer, having provision for forced lubrication of the cutting edges at a pressure of 75 lb. per sq.in. so as to prevent chips adhering to the flutes. From the attached sketch it will be observed that the final reamer is of the three-lipped straight fluted type, mounted in a floating holder permitting a certain amount of universal movement and so leaving the reamer free to follow accurately the existing bore. The experience so far obtained shows that the reamer will be satisfactory for the final processing of 12 valves, so that the question of tool maintenance will arise, but if advantage is taken of the maximum limit the life of the reamer will be extended by permitting the necessary regrind to give satisfactory sizes within the stipulated tolerances. Experiments are proceeding with "D" bits, which will give considerable reduction in tool maintenance costs, and so far progress is encouraging. The amount of material to be removed by the tools in the final operation has yet to be determined however. It is known that unless there is sufficient material for the "D" bit to cut, unsatisfactory boring results. Meanwhile investigation with regard to the introduction of "D" bits will be continued, and if it is found possible to introduce this type of borer still further reduction in cutting time will result. RHC.{R. H. Coverley - Production Engineer} | ||