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).
Ideal chemical composition and manufacturing method for brake drum material.
| Identifier | ExFiles\Box 141\3\ scan0327 | |
| Date | 8th November 1934 | |
| 8th November 1934. BRAKE DRUM MATERIAL. Recent research carried out on brake drum material has resulted in the following:- An ideal composition is as follows:- Analysis: Total carbon 2.95% Combined carbon .55% Graphitic carbon 2.4% Silicon 1.9% Sulphur .028 (maximum) Phosphorus .03% Manganese .74% Nickel 1.22% Chromium .02% In effect this is grey cast iron with notably high silicon and nickel contents and notably low phosphorus content. These features together with the method of manufacture tend to prevent the segregation of large areas and laths. Method: Preferably melting should be carried out in a high frequency electric furnace. The temperature in casting should be no higher than necessary. The agitation induced in the melt by the high frequency electric furnace is a really desirable feature, ensuring homogeneity. Metal moulds should be used, that is chill casting, and the areas of white iron thus produced on the surfaces should be machined away. The working face of the drum will then be a net-work of soft ferrite with infillings of fine graphite and hard sorbitic pearlite. Note that there should be no heat treatment after casting, the metal remains in the dendritic state thus made. An ideal physical structure is obtained which we have proved to be most satisfactory. Throughout the intention should be to avoid all formation of large graphitic patches. MH{M. Huckerby} | ||