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).
Tests of moulded insulating materials and moulded commutators.
| Identifier | WestWitteringFiles\I\September1922\ Scan63 | |
| Date | 14th September 1922 | |
| ORIGINAL To R & E.{Mr Elliott - Chief Engineer} from EFC. c. C.J. & FN. c. RyA EF. c. Wc. & Da.{Bernard Day - Chassis Design} c. Wor{Arthur Wormald - General Works Manager}/Mr. Brock. EFC1/114.9.22. X. 2494 - RE TESTS OF MOULDED INSULATING MATERIALS. Further tests of moulded insulating materials, Elo, Bakelite and Mouldensite, have been made, more particularly as regards shrinkage and effect of high temperatures. Copies of my assistant's reports FB.45 and FB.50 are attached. It will be seen that of the three materials Elo, Bakelite and Mouldensite, the magnitude of the shrinkage is in this order. As regards moulded commutators and with reference to your Wc/M12.8.22, we have made enquiries as there suggested and it appears that moulded bakelite commutators from U.S.A. are in every respect satisfactory and used by nearly all the American makers on generators as well as on starter motors, and the bursting of the commutator is unheard of. Standard wood-flour bakelite is used, the dovetail has a rather blunter angle between than is habitually used with mica construction. Westinghouse have made bakelite commutators with micarta sheets in between the segments for 12 years and many other makers now also use this form of separation. The Bakelite Company of America have been written to as to the particular grade of mixture habitually used. The Westinghouse Electric & Manufacturing Co. have been written to and report as follows :- "There is not very much in the way of definite information that can be put in the form of a letter. We all get our material from the same source. The results we have obtained on this type of commutator is due more to the gradual acquirement of experience and skill than to any particular thing. The chief thing to watch out for is the proper curing of the material, and in our experience the details of doing this had to be worked out individually by the manufacturer. We have found the development of these commutators has taken quite a long time and considerable expense which would not have been warranted had not our quantity been very large. It is barely possible that the quantities your English Company would use would warrant the amount of development necessary. The process of moulding the commutator results in a lower production cost, but no better res product from a performance standpoint". | ||