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).
Use of mica dust as a filling for Bakelite and its properties compared to shellac.
| Identifier | ExFiles\Box 50\5\ Scan069 | |
| Date | 25th May 1922 | |
| X 4333 BY4-H.{Arthur M. Hanbury - Head Complaints} 25. 5. 22. -------------------- FILLING FOR BAKELITE. X 4333 With reference to the last paragraph in E3/M.{Mr Moon / Mr Moore} 23. 5. 22. personally I do not remember seeing a memo from OY. stating that mica was used as a filling, but we use mica dust in making up the coils by mixing the mica dust with shellac. We then found that the compound in question became quite hard and was a very great improvement upon the shellac alone, in regard to resisting heat effects as well as from an insulating point of view. I am mentioning this because possibly this matter may have been mentioned at West WitteringHenry Royce's home town in a memo from Derby. In any case, since the mica dust when used with shellac was an improvement, it is quite possible that Bakelite plus mica would have improved qualities, although it might on the other hand be more brittle and have a reduced tensile strength owing to the effects of the mica. The commutator which burst on the way to Dover was not as at first supposed "all moulded" type, but was a "built up" type, precisely like the two which failed. BY.{R.W. Bailey - Chief Engineer} | ||