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).
Foundry practices, detailing core making, moulding techniques, and supplier interactions.
| Identifier | ExFiles\Box 148\5\ scan0164 | |
| Date | 31th May 1937 guessed | |
| (sheet 2) Every facility is provided for the core makers in the way of equipment. We saw one girl making cores for a fairly long 6 cylinder head of medium complication at the rate of over 16 cores an hour. Such a core I understand would in our own works be made by a fully skilled moulder with a probable time of 50 minutes per core. Wax vents are not used anywhere and wiring is conspicuous rather by its absence than otherwise. Longitudinal open vents were employed on cylinder head cores but for most of the manifold and pipe cores there is no venting at all and they rely on the porosity of the core itself. Most of these appear to be made on the blowing machines which produce a lightly packed consistent porous texture of core structure. Such cores cannot be handled previous to baking except in cradles. Table moulding should also have some advantages in respect to the texture of cores and moulds produced. We saw a number of complicated combined inlet and exhaust manifolds which are cast in one complete unit for various mass production chassis, these were made up on moulding plates for economical production, the inter structure being built up from a series of simple core forms. Previous to seeing these we should not have asked the foundry to tackle such a job. I had some conversation with Mr Bigg on the question of cooperation between the foundry and design. He rather feels that the foundry man taken generally speaks a language of his own and is not very good at making his wants known. At the same time there is a varying response from the design side they find in the firms with whom they have to deal. He told me confidentially that the people they dislike dealing with most are Talbot's who only require small quantities and ask for weird and wonderful castings very difficult to produce, to which they will consider no alteration. Talbots however are part of the Hillman group, and hence have to be studied. Bigg said that he considered metal patterns were necessary for any quantity over 20 to hold down their castings to the required thickness of 5/32" for manifolds and cylinder head water jackets etc. The normal quantities for which they quoted varied from 500 to 1500, and of course they had come very big continuous production contracts. Although their metal patterns are not what would be called a Tool Room job they take a lot of care to correct them for accuracy as their quotations are based on the finished casting being within a fraction of an ounce. | ||