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).
Laboratory report from Ford Motor Company regarding the unsuitability of a material for gear construction.
Identifier | ExFiles\Box 136\1\ scan0256 | |
Date | 17th November 1937 | |
Ford Motor Company, Ltd. 1155 DAGENHAM, ESSEX. 17 Nov 1937 A-1 Messrs Rolls-Royce Ltd. DERBY Attention Mr F J Hardy. Dear Sirs: Your ref. Rm{William Robotham - Chief Engineer}/FJH{Fred J. Hardy - Chief Dev. Engineer}/.15/AP. With further reference to your letter of the 8th instant concerning Fabroil material. Our Laboratory report as follows: MATERIAL The gear has apparently been made from cloth in the nature of a 13 oz. duck. This is unsuitable because: 1. The closeness of the weave and thickness of the cloth prevent the resin from flowing freely during the moulding operation. 2. The size of the thread does not allow of efficient penetration of the resin between the fibres. The former condition gives rise to irregularity in composition (cloth/resin ratio) and presents the very undesirable feature of layering of the cloth and resin, which is shown by a hardness variation of 86 to 96 "B" scale Rockwell in the rim of the gear, and by the more obvious cloth distortion in the web. The latter condition, which permits of relatively large bundles of cloth fibres being devoid of impregnating resin, implies that there will be minute areas all over the tooth section having virtually no resistance to crushing and surrounded by a matrix of brittle resin. Under load the resin crushes into the fibre and particles then drop out, giving the tooth a pitted appearance which is clearly visible to the naked eye. An examination of the attached photo-micrographs (marked A & A2) taken at 10 magnifications reversed view respectively, show one of the cracks starting in the resin. The cloth used in the fabrication of the sample block of material is apparently a fine duck of about 7 ozs. weight and consequently will be much more suitable for fabric gear construction. The very uniform hardness of 90/93 "B" scale Rockwell and entire absence of cloth and resin layering are ample evidence of this (photo-micrograph B). It is, of course, recognized that a moulded sheet will be more uniform in texture than a moulded gear form employing widely differing thickness over the section, and it is the experience of this Company that where a fine cambric of 4/5 ozs. weight cannot TELEPHONE: RAINHAM 3000. TELEGRAMS: FORDMOTOR, TELEX, DAGENHAM. | ||