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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).
Reasons for abandoning aluminium bronze castings due to machining difficulties, supplier bankruptcy, and unsuitability for brazing.

Identifier  ExFiles\Box 148\3\  scan0041
Date  5th December 1927
  
R.{Sir Henry Royce} C. Hs.{Lord Ernest Hives - Chair} X1476
C. Rg.{Mr Rowledge}
C. Wor.{Arthur Wormald - General Works Manager}
RECEIVED

BY4/G.5.12.27.

CASTINGS IN ALUMINIUM BRONZE.
--------------------------

Referring to R1/M1.12.27. I am afraid the information conveyed to you suggesting that aluminium bronze has been abandoned in many cases because of its difficulty in machining same is incorrect. No materials are altered without my special consent, and in the one or two cases where I have changed from aluminium bronze to ordinary bronze it has not been a question of machining at all but due to the amount of scrap. Originally I was more responsible than anyone else for the adoption of aluminium bronze, and I recommended it on the grounds that at that time we were able to find a firm who specialised in producing die castings in this material. Unfortunately their promises were nothing like the final product we received and a large amount of scrap had to be faced even in the form of die castings, and finally the firm went bankrupt. This meant that I had to reconsider the conditions under which aluminium bronze had been originally specified, and where it had been specified under the impression that we would get die castings cheaper and practically to size we had to revert to gun metal or stampings.

The steering box material was changed on the ground of the amount of scrap produced, even although the cost of the castings had been increased two or three times by the addition of runners, risers and special gates, in order to try and avoid it. There was no reason of difficulty in machining at all in this changeover.

Where strength was considered to be of importance no change has been made from aluminium bronze except to steel. One other reason for changes being made was that originally the Laboratory reported that aluminium bronze was good where brazing was required - we therefore specified alumumium bronze for die castings in a number of cases where we should normally have used steel forgings.

Incidentally the centre of the rear spare wheel carrier for the 20 HP. is an example of this particular form. In practice we found that aluminium bronze was altogether unreliable where it had to be brazed, and here again changes had necessarily to be made.

We are still using aluminium bronze sand castings in one or two cases where strength is one of the reasons for
  
  


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