The Machining of Metals

Well the clue is in the title but just in case you'd missed it, the opening narration informs us that machining is, indeed, the use of one power tool to cut through - usually in layers - other bits of softer metal. That's illustrated in close up as the planes and milling machines, borers and drills, grinding wheels and, of course, a lathe do their work. Though there's a great deal of automation going on here, it's all still heavily reliant on human supervision and intervention. How does this all work, then? Well it starts by telling us what metal actually is. It might look smooth, but under a microscope it's actually quite an irregularly formed series of grains. It's applying the pressure to these grains, or their slip plains, that enable metal to be cut - but not always in the same way. That has to be tested in advance so brittle metals can be identified, or ones that are more ductile. Hardness is also measured so the tools are capable of actually doing any cutting. The film also explains a little of the differing designs of the pieces used including those with single and multiple cutting edges - and this is a seriously precise manufacturing process. The film identifies issues that may impact on these processes - friction, heat, lubrication, etc and it's fair to say there are a multitude of variations at work here. . Yes, this is a dry as a bone, but it's designed for a scientific immunity to for those intending to join it, and for a general audience is unlikely to engage. That said, though, it's quite an informative guide to the various methods of producing metals from crucibles, moulds, ingots, sheets - you name it. The camerawork is effective at getting to the heart of the procedures and illustrates well the successes (and the occasion messes) that are turned out in huge-scale operations. Did you know there was such a thing as "red" hardness?