[TheForge] Re: Air Hammers Paul

Mon Apr 7 02:57:01 2003

Yup know all about that but in a little different use.  The silicon wafers
your computer are made from, are cut using a wire saw, the wire saw has 4
drums and 360 miles of wire wrapped on the drums an spools in grooves, to
cut wafers .040 thick it cuts up to 700 wafers from a single ingot.  The
spools are made from the nitride steel and cooked in the very same process.
The wire is coated with a diamond or silicon dioxide based slurry and only
used once, so you can see the need for drums that don't wear out, 360 miles
of wire cuts an ingot in 18 minutes, amazing it doesn't do the same damage
to the drums.

Paul Hewitt

----- Original Message -----
From: "Mike Spencer" <[email protected]>
To: <[email protected]>
Sent: Sunday, April 06, 2003 11:47 PM
Subject: [TheForge] Re: Air Hammers Paul

> > 1.) What is nitride steel?
>
> >> ams 6487 (h-11 tool steel) not that that means much
>
> Not to me.  I once worked for Michelin in their wire rolling/drawing
> mill.  They had capstan drums for one stage of the process, about 10"
> in diameter and 14" long.  For reasons I can explain in boring detail
> if anyone cares, they had to have perfectly uniform OD.
>
> They were ground to tolerance using an optical comparator and then put
> in a sealed oven in a pure nitrogen atmosphere and held at some fairly
> high temp for many hours.  Theory was that a very thin layer of the
> surface converted to iron nitride, an extremely hard substance.  Then
> many miles of wire rolling across it it high speed would take much
> longer to begin to score the surface and make the drum unusable and a
> candidate for regrinding. (Now that I think of it, I don't know what
> kind of steel the drums were made of and I forget if they ran in a
> corrsive environment but I think they did so they might have been some
> kind of chrome or nickel alloy.)
>
> As an aside, some of their tech was very ingenious but some of the
> machinery was unchanged from circa 1910.  And they had a pair of
> braided boot lace machines fed with spools of fine wire for both braid
> and core.  A 3" or 4" length of braid (with the core removed) made a
> springy thing like a Chinese finger puzzle that could be used to butt
> splice wire in the process of feeding the machines that made the tire
> belting.  Lovely machines, works of art, clever splice.
>
> - Mike
>
> --
> Michael Spencer                  Nova Scotia, Canada
>
> [email protected]
> http://home.tallships.ca/mspencer/
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