The Manufacture of Diamond Tools
Production of Wheel Dressers, Shaped Tools and Hardness Indentors
by Two Leading Firms
This article first appeared in the Volume 4, Number 46 (August, 1942) issue of Aircraft Production magazine, and is presented here through the kind permission of Flight International. Thanks also to Bruce Vander Mark for furnishing volumes of Aircraft Production for scanning.
With the great expansion in production of close-limit machined components for the aircraft industry, the importance of diamond tools becomes increasingly evident. Very little literature on their selection and use has hitherto been available and it has been the considered policy of Aircraft Production to disseminate as much information as possible on this important phase o f production.
In this article we describe the manufacturing methods of A. Shaw and Sons, and L. M. Van Moppes and Sons, two o f the leading firms engaged in this work, together with useful information regarding types of diamonds and tools, and recommendations regarding their care and maintenance. Previous articles dealing with the types and use of diamond tools appeared in our March, April and June, 1942, issues.
Industrial diamonds, although of the same origin and composition as the polished stones used for the gem trade, differ in colour and structure. They are often cross grained and may be brown, grey, cloudy-white, or even a good colour, but containing black carbon spots. Stones with irregular grain, such as ballas, which has a radiated internal structure instead of the usual octahedral structure, cannot be polished, and so these, together with the other types also mentioned above, are separated from those suitable for gems and are then given to experts to be selected for various industrial purposes. These industrial diamonds range in quality from perfectly sound and flawless stones to those possessing some defect of inclusion, known as crushing boart, which renders them suitable only for crushing into powder.
The diamond industry is highly specialised, and it is extremely doubtful therefore whether any actual user of industrial diamonds can determine by sight whether he is receiving good stones. He is entirely in the hands of the diamond tool manufacturer and if for no other reason it is obviously advisable to deal only with producers of repute and standing. More than with any other commodity can a “cheap” purchase prove expensive. Colour does not greatly affect the properties of the stone, although some users consider grey and white stones to be harder than the various shades of brown. If they are harder, the advantage is offset by increased brittleness, and for this reason brown stones will stand more abuse than other colours without breaking up. It is important that the stone should be free from flaws, inclusions or fractures and here again the buyer is largely at the mercy of the tool manufacturer.
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