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 Wellworthy Piston Rings discussing methods for testing the wear value of centrifugally cast piston ring material.
| Identifier | ExFiles\Box 148\3\ scan0386 | |
| Date | 31th August 1938 | |
| WELLWORTHY PISTON RINGS LIMITED CONTINUATION No. 1 Messrs. Rolls-Royce Ltd., 31.8.38. way of testing as to use a strip cut length wise from the pot and use a diameter of 1/4", we should have on the one hand material from the outside of the pot which is relatively high tensil and high En values, whereas a material from the inner surface of the sulphide pot we have low physical value which works out in any calculations. You will appreciate that in centrifugally iron impurities are squeezed out so to speak into the bore of the pot and just as a general example you take the sulphide content only, this on all centrifugally castings comes out to a very close figure, simply because it is centrifuged and flows over the end plates of marble during the casting operation, by being squeezed out from the material, which is spun centrifugally in the die. We do know there is a different wear value between the outside of the material of the piston ring casting as compared with the inner surface and would suggest that if you could accommodate discs which are machined from the radial thickness of the pot, and we on our part would remove from them the 1.1/4" mm of material from the outside surface which is our standard practice on the manufacture of rings. We would, then, no doubt be able to make provision to hold these in contact with the discs for wear tests. To get the really true values it would at all times be necessary for us to cut these discs from the pot which is appropriate in size to the ring size of this manufacture. One of the best wear machines we know of is used by the American Hammered Ring Company, and our own Foundry who adopted the same type of machine, and specimens are usually 1/4" diameter, and made to the maximum length which can be taken from the radial thickness of the casting from which the rings are made. Perhaps you would be good enough to comfirm that you agree our suggestions on this matter, and as the Writer proposes calling at your Works next week, we shall be very pleased to have a discussion with you on this if you so desire. Yours faithfully, for WELLWORTHY PISTON RINGS LIMITED. F.{Mr Friese} Blackith Technical Manager. | ||