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 to High Duty Alloys, Ltd. discussing heat treatment and hardness testing procedures for bearings.
| Identifier | ExFiles\Box 115\5\ scan0071 | |
| Date | 1st July 1938 | |
| Copy to Mr. Robotham. JH/CJR. 1st July, 1938. W. C. Devereux Esq., Messrs. High Duty Alloys, Ltd., Trading Estate, Slough, Bucks. Dear Mr. Devereux, A.C.9. Thanks very much for the visit of your Mr. Richards. The points which we discussed were as follows:-- He checked over our pyrometers and agreed that they were within 4-5° of his own, so we agreed that that was correct. He agreed that our method of Rockwelling, for which we have been in the habit of using a 1/16 ball, would probably have more accurate readings if we used a 1/8 ball, and that we have agreed to do in future for this job. He also stated that in his opinion 12 hours at 180, in the casting form, should be perfectly satisfactory heat treatment, but he also stated that in his opinion it would not be detrimental, if the Brinell reading still remains on the low side as it is doing at present (within the low specification on the low side), to try slightly increasing the temperature, but that the maximum temperature above which we could not go would be 240°. It was agreed between us that in the next batch of bearings that we make, we should cast a fairly useful surplus over and above the quantity required, and that we should heat treat part of them here and send the others for you to heat treat, and then compare the Brinell figure obtained by both Companies. The position is, therefore, that the Leyland, Dennis and other bearings which we have got in the shop have now gone into the machine shop after having had 12 hours at 180, and they have been coming out showing a Brinell figure on the bottom side of the range, but the Bristol Aero job, to which we gave a further 12 hours (24 hours altogether), with a 1/16 ball showed a Brinell of 59/60, which probably had we have been using a 1/8 ball at that time would have shown 62/63. I thought perhaps I would just put it on record that | ||