Another patend that was "liberated" after the war from Germany, was the
formula for making "shell core sand", which is used in the foundry industry.
The holes and slots in castings were actually small sand columns and shapes
in the sand mold before the molten metal was cast into the mold. As a rule
these were very brittle and easily deformed prior to and during the casting
process - causing a high percentage of scrap. Germany had perfected a
process using formaldehide (sp?) that bound the sand cores together with an
almost plastic consistency, but then broke down into just plain sand when
subjected to high heat (like molten metal). It would remain stiff for a few
seconds, just long enough for the surface metal to solidify around the hole,
then would collapse. I understand that this was developed for use in
manufacturing the famous (or infamous) 88mm shells.
After the war, this revolutionized the foundry and casting industry all over
the world. It would be difficult to find a foundry that did NOT use shell
core sand. Remarkable stuff.
Tom Campbell - Birmingham, Alabama
(metallurgical engineer in a previous lifetime)
This archive was generated by hypermail 2b29 : Tue Jun 05 2001 - 23:18:34 PDT