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).
Test results and analysis of cadmium plating on test pieces, focusing on fracture angles and potential causes of failure.
Identifier | ExFiles\Box 30\6\ Scan066 | |
Date | 14th December 1928 guessed | |
2. Table 2. (cont.) Test Piece No. Angle at which Fracture commenced. "As received" Cadmium Plated. 7 40° 40° 8 40° 38° 9 40° 40° 10 40° 40° 11 40° 40° 12 40° 40° Table 3. Test Piece No. Angle at which Fracture commenced. "As received" Cadmium Plated & Treated. 1 42° 39° 2 42° 40° 3 40° 40° 4 40° 42° 5 42° 42° 6 40° 40° 7 40° 40° 8 40° 40° 9 40° 39° 10 42° 42° 11 42° 42° 12 42° 40° A number of other tests, including various bend tests and Izod tests on larger bars, also failed to confirm the presence of brittleness after any of the operations involved in plating, or in the finished parts. We consider that the cleaning and acid dipping operations, as carried out in normal production work, on parts to be cadmium plated, are of such short duration that there is no possibility of appreciable hydrogen absorption taking place. We have always strongly emphasised the necessity for keeping these operations quite short, and with this object in view we have recommended that parts for cadmium plating should be practically clean before reaching the electrolytic bath, which should be regarded as a means for producing chemical cleanliness rather than for removing heavy dirt etc. We suggest for your consideration the possibility of the threads on the failed screws having been too tight, as we note that the part in question is of a shape which renders it possible to put great stress on the screw. A tight thread would result from :- (a) An insufficient allowance being made for plating. or (b) A somewhat thicker coat of cadmium than usual. H1. HE | ||