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).
The properties and applications of insulating materials like Bakelite, Condensite and Dilecto for various components.
| Identifier | ExFiles\Box 39\3\ Scan076 | |
| Date | 10th December 1920 | |
| R.R. form 788. 10-12-20) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 9347 -3- Contd. on coils having cotton covered wire, since the Bakelite varnish before baking dissolves both enamel and silk. Bakelite discs, washers and tubes, however, can be used on any coil since after baking the Bakelite is inert. Properties of Bakelite or Condensite. We understand that Bakelite and Condensite are practically the same. Our coil cases are of Condensite. Page thirteen of the Condensite folder enclosed describes the properties of the basic substance and states that it is anhydrous, non-hygroscopic, of high dielectric resistance, hard, unaffected by temperatures below those at which it begins to carbonise, very strong, etc. This description applies to the basic substance and not to the commercial materials which are all "loaded" with some sort of filler. For ignition distributors, sawdust is used, we believe; for clutch facings, chopped cork, and for heat resisting compounds asbestos in some form. The filler affects the physical properties of the material, thus Bakelite Micarta (paper or duck base) and Bakelite Dilecto (paper base) or Continental Bakelite (duck base) are not recommended for temperatures above 220° F.{Mr Friese} steady or 300°F.{Mr Friese} intermittent. Bakelite Dilecto, grade A, is formed on a base of asbestos paper and cannot be destroyed except by putting in a fire, and the same can be said of the "Mica-Micarta" (or bakelite micanite) made by the Westinghouse Company for very severe conditions. Mr. Royce will be interested in grade S. Bakelite-Dilecto, which is coated on one or both sides with hard rubber, to get away from the "spark tracking" trouble. The price lists of Bakelite Dilecto, etc. enclosed may be interesting to Mr. Royce. The enclosures will be of interest to Mr. Royce: 1. "Condensite" describes molded condensite insulation. 2. "Insulation" (Continental Fibre Co.) describes the General Electric Company's sheet materials. 3. "Molded Insulating Materials" (Johns-Manville Co.) describe various types of molded material, asbestos and rubber, mica and shellac, J.P.No.201 apparently containing asbestos, and ordinary molded Bakelite. Johns-Manville produce 80% of the World's asbestos products. 4. "Moulded Insulation" (Cutler-Hammer) describes two new cold moulded inorganic insulations for switch bases, etc. with great heat resisting qualities. Contd. | ||