MAGNETS IN INDUSTRY.

Auckland Star, Volume LXI, Issue 95, 23 April 1930, Page 23

MAGNETS IN INDUSTRY.

A TOOL THAT STICKS TO ITS JOB

One day a clever engineer .was watching a gang of men unloading great chunks of \ scrap-iron from a railway ttruck. The work was .heavy and awkward, and eacli truck took a long time to empty. Often a piece would slip and give a man a nasty gash or break a bone. Well, as you know, engineers hate to see men doing work that can be done mechanically. So this engineer thought why not have a giant magnet to lift all the junk up-at once? The idea seemed worth trying, and to-day, in many iron and steel works, lifting magnets are in use. These magnets are electric magnets. They are simply a bundle of copper wire enclosed in steel housings. Electric current passing along the wire produces a magnetic field which is an invisible force attracting metal which come close enough to it. Here are a few of the, uses to which these magnets are put. Sometimes the pieces of scrap metal to be melted down are too large to go into the furnce and have to be broken. This is done by dropping a large steel ball, called a skull cracker, on to the pieces. The ball, which may weigh 20 tons, is lifted by the magnet, and when high enough, the current is switched off, and down comes the ball, and metal flies about just as if you were cracking a nut with a hammer. Hot pieces of iron are also removed in the mills by magnets; in fact, all shapes in. steel work, such as plates, rails, girders, etc., are handled by them as easily as a.mother carries a young baby. One unusual job a magnet was once asked to perform was to remove a cargo of nails from a sunkau barge. The nails, which were in casks, were raised without being unpacked. As the magnet in this case was absolutely waterproof, no harm was done through submersion. The magnet may be made to drop its load instantly by switching all current off at once, so that the loa.d is placed down gradually. Magnets arc of two distinct shapes. The circular magnet lifts pig iron, scrap iron and smaller pieces, and the rectangular is used for lifting plates, pipes, rails, girders, etc. The circular magnet consists of a coil of wide copper ribbon, insulated with asbestos wound on to a steel bobbin, which is part of the magnetic circuit. This coil of copper is fixed between the magnet body and the bottom plate. Moisture must be kept out of the magnet body, and to ensure this a compound is forced into metal at a pressure of 1001b to a square inch. This process also hardens the case to resist the naavy blows the magnet gets, for the pig iron leaps up and hits the magnet with great force if the current is switched on before the magnet touches the pils. Magnets are also used in the making of.our food. When rice, oatmeal, flour, etc., are being made, metal shavings may drop in off the machinery, so a magnet is used to remove them. •• < - • .Sometimes, too, nails, 'bolts, etc., find their way into other raw material, and

if not. removed in time would; damage very expensive machinery. The magnets are suspended above a conveyer carrying the raw material, and the iron pieces are collected by the. magnet.. Another use for the magnet is as a ; scavenger in.rubbish tips. Have you ever seen people going through rubbish , tins in search of valuables ? Well, that is what magnets do in some salvageworks and places where the dustman empties his load. So, as well as being a toy to entertain a, boy,-the, magnet is a" very useful tool in the ' world. . . . " '