Milling by Stan Bray

图书介绍

Milling is the opposite to turning; in the latter, when using the lathe, the work will usually rotate and the cutting tool be held still and rigid; in the former, when milling it is the cutter that rotates, the work staying still. Possibly those statements require a little clarification, because, although the tool when turning and the work when milling are held rigidly, in both cases the surface to which they are fixed is able to traverse, usually in two directions, known as 'X' and 'Y'. The milling machine has an additional movement, known as 'Z' that, as a rule, is used for the depth of cut.

Although lathes have been in use for hundreds of years, the true milling machine, the main task for which is to generate flat surfaces, arrived much later. Before then the blacksmith would hammer metal to shape, and special finishes or surfaces requiring a greater degree of accuracy would be filed or scraped. Not that those skills have by any means been dispensed with even today, but they are certainly much less used and the craftsman who can scrape a piece of steel or some other metal so that is flat to within a thousandth part of an inch or a hundredth of a millimetre is rare indeed.

The lathe was and is still used for certain types of work where a true, flat surface is needed, and for large areas it was customary to use a shaping machine or a planer, both of which produced particularly fine finishes, but these are now generally considered as too slow for modern industry. The modern machines used for this sort of work, if we forget about the multipurpose machining centres used in industry, are milling and grinding machines. The latter are able to produce a finish of high quality to a high degree of accuracy. But while a few people have adapted milling machines to carry out grinding operations, grinding machines have only a limited use, generally being confined to obtaining highly accurate and superbly finished work, having followed on from treatments carried out on other machines.