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).
Letter from Ferodo Limited concerning the metallurgical analysis and comparison of Millenite brake drums.
Identifier | ExFiles\Box 141\3\ scan0325 | |
Date | 8th November 1934 | |
From FERODO LIMITED. Sheet No. 2. W. A.{Mr Adams} Robotham Esq., Messrs Rolls-Royce Ltd. 8th November 1934. cast iron to the theory, and almost simultaneously commenced a series of tests on a Millenite drum which had exactly the same structure. Believing this to be the characteristic Millenite structure, we felt quite safe in going ahead and recommending Millenite (quietly, of course, and unofficially.). Seeing these two photomicrographs of yours, A.759 and A.1156, rather leads us to the conclusion that there is nothing very definite or very scientific about Millenite, and that it is not altogether safe to recommend it. Briefly, the position is as follows: (1) The structure of the cast iron recommended by us is identical with that of the original Leyland Millenite drum tested and found satisfactory by us. (2) The drum described by Print 759 does not resemble this structure very closely. (3) The drum represented by Print A.1156 is totally dissimilar from the original proved structure. (4) It is interesting to note that the analysis given in our recommendation tallies very closely with that of the Lake & Elliott drums. (5) I note on the back of the photograph A.1156, the Phosphorus is given as .3 and on the Laboratory report as .03. It would be interesting to know which is the correct figure. If the Phosphorus in the faulty drum, A.1156, is .3%, whereas in the satisfactory drum, A.759, it is only .03, and in our specification it is also only .03, then you will notice that in our specification we state that the notably low phosphorus content, combined with the high Silicon and Nickel content, tends to prevent the segregation of large laths of graphite, which is the great fault with the drum A.1156. The outlook I have on the actual Millenite drums may be wrong, in that they are possibly not the views of an expert metallurgist, but I feel that Lake & Elliott are following chemical composition slavishly, and do not realize that a satisfactory drum must have the ideal physical structure, as depicted in the sketch above, and that such a physical structure can only be obtained by following that manipulative method described in the above specification. I think probably it would be rendering a service to Lake & Elliott if they were advised of the importance of the physical structure, but such advice would come better from you than from us. | ||