From: ahahma@polaris.utu.fi (Arno Hahma)
Newsgroups: rec.pyrotechnics
Subject: Re: Explosive bonding... (NEW TOPIC)
Message-ID: <1992Apr27.145154.28828@polaris.utu.fi>
Date: 27 Apr 92 14:51:54 GMT

In article <1992Apr26.041448.10001@ucc.su.OZ.AU> bill@extro.ucc.su.OZ.AU
(William Logan Lee) writes:

>You must suspend one end of the plate (near the initiating point) lower than
>the other end so that the welding excludes air and jet fragments as it
>progresses across the sheets. Too close and the material doesn't have the
>chance to accelerate enough to intermix the two materials; too far away and

This will work only for relatively small pieces. With long distances
to be welded, the far end of the plates would be too far apart leading
to cracking or incomplete weld. The plates can also be parallel, as
long as the distance is suitable, not too close nor too far.

>ANFO has a detonation velocity too low for good welding.  The explosive
>used is typically a PETN sheet explosive (ICI trade name "Metabel") with a
>high detonation wave velocity. I doubt that ANFO could be packed neatly

That is somewhat incorrect. The detonation velocity is selected
according to the materials to be welded. ANFO may be sufficient for
some materials (such as copper and aluminum) whereas others may demand
PETN and the like. The thickness of the material also affects the
velocity needed.

The sheets do contain some high explosive, but they are likely to be
"diluted" in some way to slow down the detonation velocity to a
desired value. Of course, the sheets are available for almost any rate
less than 8500 m/s, the velocity depends on application. Naturally, it
is far more convenient to manufacture all the sheets of the same basic
explosive than use maybe tens of different explosives for different
detonation velocities.

>a detonation wave though the thin layer of explosive anyway.  (I think,
>from memory, that ANFO requires a minimum 3" diameter column of contained
>explosive in order to propogate reliably. Actually I know I have loaded holes

You remember correct. The critical diameter is about 5..10 cm,
depending on the confinement. Such a large critical diameter does not
prevent you from using ANFO for welding. You will only need more of
the explosive and the material has to be thicker. Granted, ANFO is not
for fine working.

>PS: In 1989 there was a simple article in "The New Scientist" on Explosives
>in Engineering.  Try your local University Library for info on this.
>Much of the work on this is unpublished as it forms the basis of specialised
>commercial work.

Much is published, too. There is even a book of the techniques:
Schroppe & Wolf, "Hochgeschwindigkeitstechnologie der
Metallbearbeitung". The book also describes other than explosive high
speed technologies, such as hydroelectric and magnetic methods,
oxyacetylene cannons for spraying metals, smokeless powder propelled
guns for impact molding etc. A very informative book with some theory
as well (how to calculate the charges, for instance).

>Bill Lee

ArNO
    2

From: ahahma@polaris.utu.fi (Arno Hahma)
Newsgroups: rec.pyrotechnics
Subject: Re: Explosive bonding... (NEW TOPIC)
Message-ID: <1992Apr28.100304.3141@polaris.utu.fi>
Date: 28 Apr 92 10:03:04 GMT

I wrote:

>Much is published, too. There is even a book of the techniques:
>Schroppe & Wolf, "Hochgeschwindigkeitstechnologie der
>Metallbearbeitung". The book also describes other than explosive high

Sorry, the author is misspelled and incomplete - it happens, when you
try to remember things by heart. The correct reference is:

Neubauer, Stroppe and Wolf, "Hochgeschwindigkeitstechnologie der
Metallbearbeitung", VEB Verlag Technik: Berlin, 1. Ed., 1988.

ArNO
    2

From: ahahma@polaris.utu.fi (Arno Hahma)
Newsgroups: rec.pyrotechnics
Subject: Re: Explosive bonding... (NEW TOPIC)
Message-ID: <1992Apr29.060609.8086@polaris.utu.fi>
Date: 29 Apr 92 06:06:09 GMT

In article <1992Apr28.152917.14284@ucc.su.OZ.AU>
bill@extro.ucc.su.OZ.AU (William Logan Lee) writes:

>>[German reference book named:]

Neubauer, Stroppe & Wolf, VEB Verlag Technik: Berlin, 1988

>Do you know of an English translation for the aforementioned book?

It may be difficult, if not impossible to get an English translation
of the book. As you can see, the book has been printed behind the
curtain, during the "dark ages" (VEB == Volkseigener Betrieb, A
company owned by the People, sounds nice, doesn't it ]-). I don't
know, if the Verlag Technik (Press Technology) exists any more. It may
have been bought by a western company, most likely Springer Verlag or
Verein Chemie Verlagsgesellschaft (VCH), so you might ask them.

The title in English is: High Speed Technology of Metalworking, if
translated word by word. You could try searching with something like
that.

>Bill Lee

ArNO
    2