RE: [CAD_CAM_EDM_DRO] Re: Casting clearance

If you are wanting to build up a film and not use the real release agent,
you may want to consider using PVA (Poly Vinyl Alcohol). It is used in
fiberglass molding and is quite inexpensive. It is a medium viscous liquid
that can be thinned with ethyl alcohol and is normally applied by spraying.
It dries rapidly to a thin plastic film. Usually you use a release wax (a
paste that builds no thickness) on the part first and then the PVA.
Additional coats make a thicker film. After you pop the part you remove the
left behind PVA by dissolving in water.

I know it is hard to believe, but there are industries that have already
figured out just about every way to release a part.

Tim
[Denver, CO]

> >-----Original Message-----
> >From: Jon Anderson [mailto:janders@...]
> >Someone mentioned Carnuba wax earlier, I really don't think this by
> >itself would make a good release agent....
> Not at room temperature, but by applying heat, it melts
> completely, providing a
> garanteed release action.
>
> The silicone release that is recommended for the kit has no
> phase change to
> release it; it must at the same time have a consistency that
> is hard enough to
> take the casting impression, but soft enough to break and/or
> flow once you try
> to remove the cast nut.
>
> You might also consider using something that is soluble (e.g.
> shellac) as a
> release/spacer, but then you have to worry about how long it
> will take for the
> solvent to reach into the deepest crevices.
>
> >...However, it's a pretty hard wax,
> >and might do a good job of filling in imperfections.
> >Maybe the best approach would be a light lapping with a
> brass female lap
> >to remove any high spots and micro burrs, followed by a good
> cleaning,
> >then Carnuba wax to try to fill in the micro pits.
> Whether that happens depends on the shape of the pits rather
> than their size.
> The wax will fill an arbitrarily deep pit as long as its
> mouth is narrow enough.
> On the other hand, the wax will conform well to (i.e. *not*
> fill) a wide shallow
> pit.
> -Kevin Martin