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 Bakelite Limited discussing the tensile strength and insulation properties of moulding material EXX 4933/4.
| Identifier | ExFiles\Box 61\1\ scan0246 | |
| Date | 6th September 1935 | |
| HEAD OFFICES 68, VICTORIA STREET LONDON, S.W.1 TELEGRAMS: BAKELITE, LONDON TELEPHONE: VICTORIA 5441 (4 LINES) BIRMINGHAM WORKS: TELEGRAMS: DAMARDEST, BIRMINGHAM TELEPHONE: ACOCKS GREEN 1181 (4 LINES) PLEASE ADDRESS ALL COMMUNICATIONS TO THE COMPANY, AND QUOTE WEP/DAC. Handwritten: 6110. BAKELITE LIMITED Successors to The Damard Lacquer Co. Ltd. & Mouldensite Ltd. Redfern Road Works, Tyseley, BIRMINGHAM, 11. REGD. TRADE MARKS TREFOIL BAKELITE MOULDING MATERIAL INSULATING VARNISH LAMINATED CEMENT LACQUER, RESIN 6th September 1935. Rolls-Royce Limited, D E R B Y. Your ref: Hs{Lord Ernest Hives - Chair}/WST.5/MA. Dear Sirs, Further to our letter of yesterday, we have been going further into the position and it seems fairly clear that, in the first place, it would be better to confine tests to one type of material which seems to give outstandingly good figures under the sort of conditions which you mention. We do not propose, therefore, to submit the materials mentioned in our letter of yesterday but to send a 2-lb.sample of Bakelite Moulding Material EXX 4933/4 together with a disc, as you request. For your information, the tensile strength of this material on an A.S.T.M. test piece is approximately 6,000 - 7,000 lbs/sq.in., and the insulation between the terminals on the sample which we have sent to you is 150 megohms at 130°C. A similar electrical figure can be obtained from EXX 5072 but the mechanical strength falls very considerably short of the figure mentioned above, and our experience has been that this type of material is not so satisfactory for ignition purposes as the EXX 4933/4 type. We should be glad to have your comments on this material at your earliest convenience, so that we may have an opportunity of going further into the matter if necessary. Yours faithfully, for BAKELITE LIMITED. W.E. Pattman Sales Development Dept. Handwritten: Leakage between ERA electrodes at 150°C 325 megohms. Baked at four hours at 150°C | ||