Tuesday, October 21, 2008

Heads or Tails #61 -- Wire

In today's episode of that industrial-strength meme, Heads or Tails, our chief foreman, Barb, asks us to discuss "wire."

I suppose she didn't necessarily have industrial applications in mind, but I can't think of the subject without recalling a number of cases I've defended, one involving death, and the other leaving the machine operator a near-total quadriplegic.

You see, wire does not grow out of the ground. The wire we see in electrical cords or even coat hangers and shopping carts must be created, drawn through a series of dies, until the desired diameter is reached. (Here's the Wikipedia article on the subject, for the truly ambitious.)

I went browsing across the Internet this morning looking for a picture of a machine similar to the ones that I saw in operation -- ones that were involved in these types of cases -- but I had no luck.

I wasn't entirely surprised. Wire drawing equipment is still manufactured, apparently in Asia at least, but it looks quite different from the American-made machines that I've seen. The machines I saw were old. Surprisingly old. Remarkably old... and the design has understandably changed.

Here's the design I've seen: Imagine a giant turntable on a block that brings the turntable to about waist high. This turntable will rotate and draw rod through a series of dies down to the required thickness and, at the same time, wrap the wire up in a coil. The turntable is shielded a good part of the way around by a tall metal semicircular plate.

Why? Think about how hard the motor must pull to take wire that is THIS thick and squeeze it through an opening that is only this thick. Now think what happens if the wire breaks unexpectedly. If you've imagined a very fast-moving, lethal whip you're dead on.

The dies are positioned along a platform that feeds into the turntable. The dies can be changed -- have to be, because they wear out (are enlarged by the friction of pulling, for example) or break. Lubricant of some sort must be applied to the wire being drawn into that turntable. Here is another hazard point, particularly if the operator attempts to supply a little additional lubricant manually. Loose fitting gloves or sleeves can be fatal here: I'm sure you can see how.

(And Barb thought we were supposed to tell scary stories next week!)


Anonymous said...

I had no idea! I will look at wire very differently from now on, in a sort of reverent way.

Barb said...

I can sorta kinda picture that machine.. it's much easier to picture the dangers from working with one.

Scary stuff indeed.

Jean-Luc Picard said...

A really interesting post about something we take for granted.

Tumblewords: said...

I remember something about these machines - so many of the tools we use are deadly unless a great deal of caution is used! Nice post!