Outspinning the Spider: The Story of Wire and Wire Rope

by John Kimberly Mumford

Never think that the tall chimney of a manufacturing plant tells the story of all that goes on in its shadow. It isn’t all coarse work. If you could see the things that are done to a block of steel, and the brains that are mixed with it, in the Roebling plant, before it comes out and goes on its way, they would make you take off your hat to a piece of wire for the rest of your natural life. But it isn’t all, what happens to the outside. There are wire doctors who follow the changing symptoms of the metal through its many processes, with diagnostic eye as keen as any medico’s for traces of typhoid or mumps. Through all the process there are reheatings and coolings, at carefully specified temperatures, to give temper and then to take it away, to keep the ductility without sacrificing endurance. It is one business where you simply have to eat the cake and keep it, too.

There is wet drawn wire and dry drawn wire, and chemical reasons for drawing wire wet, and divers ways of drying wet wire to attain certain conditions; there is lubrication by means of dry materials as well as oil, and soap suds, funny things that also act on the material itself in mysterious ways. But this is no text book.

TRAMWAY RUNNING ON WIRE ROPE CABLE DUMPING COAL AT MINE

No thinkable effort is omitted that will help to make the wire material perfect in quality and service condition, but the proof of the pudding in the making of wire is in the Olsen machines—miraculous things that will smash a big wire rope or snap a hair of wire and register to a decimal the breaking strength of each. There are tests for tensile strength, for torsion to show how many twists a piece of wire will stand, and for bending. There are microscopic tests for molecular condition and men who will almost tell you from a microscopic section the maximum service of which the rope made from a given wire is capable. Any bundle of wire that doesn’t pass the test for the job on hand is discarded and used for something else, and a record of it all is kept with scrupulous care. Any foot of wire that passes through the shipping room on the way to market has a clean bill of health, ample for the use to which it is destined, and the amount of material that is scrapped for faults, where work is on stringent specifications, would be sudden death to a business that hadn’t a wide range of uses for product of whatever quality. Fortunately for the users of high-grade wire the market for the lower grades is always hungry and crying for more.

THE WONDER OF DUCTILITY

There are complexities without end in the making and finishing of wire, but the real wonder of it lies after all in the initial principle which the German inventor in Bavaria gave to the world six hundred years ago—the simple but even now almost incredible fact that a rod of cold steel of the hardest quality—plow steel is the convincing name for it—can be seized by its sharpened end with a clamp they call a dog and drawn through a smaller hole, in a still harder piece of steel, three or four feet until it can be fastened to a drum, and then be wound off in miles almost without interruption. It is a wonder that grows as you watch it and yet it seems so simple. To see that steel, of tremendous strength and hardness, drawn through a tiny hole as if it were molasses candy—and yet it may have a tensile strength of two or three hundred thousand pounds to the square inch.

There is nothing spectacular about the wire mill where this is done. On long benches the die-holding appliances are set up and the dies set into them. The wire—or at first the rod—is run from a portable bobbin they call a swift, that stands on the floor, and the wire, after it has been given the hole, passes to a bobbin they call a block. Then it is taken on to a still smaller die and the same process repeated, with occasional reheatings, until it has the diameter of a thread.

CUTTING THE DIES

But by and by the time comes when the wire is so fine it cuts the steel of the die and loses its rotundity. Then a harder material is needed and the wire drawer goes the whole figure and uses a diamond. Cutting the steel dies is a cunning craft enough, but the expert, who, with a hair-like drill and a dab of diamond dust can penetrate a diamond with an opening that will be regular and measure to a thousandth of an inch, is a man who would think it no trick at all to pass a well fed camel through the needle’s eye.