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 on the examination of anodically oxidised aluminium pistons from a Cadillac car after 20,000 miles.
| Identifier | ExFiles\Box 125\1\ scan0215 | |
| Date | 12th March 1935 | |
| COPY To RHC.{R. H. Coverley - Production Engineer} HL1/AG.12.3.35. Laboratory Re: Anodically Oxidised Aluminium Pistons fro Cadillac car, after 20,000 miles. One piston was submitted. We have, however, visually examined all the pistons from this car. The following points were noted :- The anodic coating has been removed or partially removed on the bedding area of the piston. The variation in thickness remaining can be approximated to by comparing the colour, after light scraping to remove carbon. The carbon is easily removed by scraping without cutting through the coating, which has a "glossy feel" to the knife. The coating is still largely present in the ring grooves but appears to diminish in thickness, as judged by colour, from the bottom to the top groove. Similar evidence is present in the gudgeon pin holes. In sundry instances when a comparatively large particle of foreign matter has been trapped between piston and cylinder wall the coating has collapsed, owing to the soft underlying material, and the piston shows a score. We were unable to conduct actual thickness measurements on the pistons, as we understood that they are to be replaced in the engine. One of the points in which we are interested with respect to this process is whether the coating is essential throughout the life of the piston in order to obtain the maximum benefit. Since it is apparently not known how far these pistons had run before the coating wore through, we suggest it would be interesting to see these pistons again, after further service. HL. | ||