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 K.L.G. Sparking Plugs Limited concerning manufacturing difficulties with Corundite plugs.
| Identifier | ExFiles\Box 162\5\ img003 | |
| Date | 29th April 1937 | |
| K.L.G. Sparking Plugs Limited CONTINUATION NO. 1. DATE 29.4.37. Messrs. Rolls-Royce, Ltd. On the subject of Corundite plugs we would remind you of our conversation when we impressed on you the difficulty which is caused in the design of these plugs by abnormally long threads or barrels; the difficulty in the first case being that we consider it most undesirable to arrange a seating for the insulator inside the threaded portion of the plug and both in the case of long threads and long barrels it becomes necessary to increase the overall length of the whole insulator to an extent which causes very serious difficulty in firing. As I think you know all of these insulators are fired at extremely high temperature and passed through the furnace standing on their ends upside down. At this peak temperature the material is almost molten and the insulator is liable to sag over to one side so that it comes out badly bent. Of course it is then quite irrecoverable and we find that our percentage of scrap due to this cause is out of all proportion higher with long insulators. We shall be most grateful if you will draw the attention of your designers to the difficulty which abnormal dimensions involve and ask them to use every endeavour to keep both length of reach and length of barrel to the least possible. We also confirm our agreement with Mr. West that we shall not at present proceed with the manufacture of finned screens to your Drawing EL.266. Yours faithfully, p.p. K.L.G. SPARKING PLUGS LIMITED. Director. | ||