Re: [CAD_CAM_EDM_DRO] High pressure water jet (Lasers)

dave engvall wrote:

> Jan,
>
> My impression also is that LN2 is about a $/L.
> However, I just found out about an application
> that throws it away. LN2 is used for cleaning blow
> molds....as in plastic bottles. The polymerized
> scum (crud that build up on the surface of the
> mold) comes off nicely when cooled with LN2.
> (differential expansion) They apparently discard
> the used LN2. So as in many things having the
> right connections could be valuable. :-)

You won't find the Nitrogen easy to grab! It explodes
in a big puff of vapor, and joins the atmosphere.
They don't have to dip the entire mold in a vat of LN2,
they just squirt it into the mold, the crud chills and shrinks
enough to break the surface bond, and the blast of gas
ejects the crud from the mold. It probably takes very little
of the LN2 to do this cleaning. A few CCs of actual liquid
is all it takes, although it may take 10 - 100 times that much
to actually cool the tubing to deliver liquid to the end of the
tube, depending on how long the interval between cleanings
is.

Jon