Re: [rp-ml] Urethane Molding

From: Bill Hearn (
Date: Thu Apr 14 2005 - 01:04:05 EEST


For small parts you can use a small vacuum pump and a
bell jar / paint pot for degassing the resin before
dispensing into the mold and for placing the mold in
for cure.

If you use a paint pot you can also apply pressure
cycles to aid in degassing.

Cheap vaccuum pumps and compressors are usually
available from;

You can also degas in the syringe fairly effectively
by cycling the plunger with the orifice / needle
blocked and unblocked to achieve vacuum and pressure
to separate air bubbles from the liquid before filling
the mold.

Warming the more viscous component (usually the resin
in polyurethanes) will help to reduce the viscosity to
something manageable for syringes.

Here are some links for materials;

--- Chris Sonon <> wrote:
> Hello all,
> I am interested in finding out information about
> Urethane molding
> materials. I am interested in finding some material
> that will be close
> in properties to Polypropylene; if someone could
> point me to a good
> online source, I would be grateful. Also, I am
> interested in
> information about small systems to remove air from
> the urethane before
> injecting it into the mold. We are going to be
> injecting SMALL parts and
> will more then likely be using a syringe. If you
> know of a small mixing
> and injection system that isn't too expensive, I
> would also be
> interested in that as well. Last, some
> recommendations of Mold release
> would be helpful.
> Thank you for any information that you can provide.
> Chris
> Christopher Sonon
> CAD Design Technician
> Iron Mountains LLC
> (610) 913-6883

Bill Hearn
Effervescent Inc.
"Waldies Comfy Foam Clogs"
24 Scott Road
Fitchburg, MA 01432
Phone (978) 502 - 8312
Fax (940) 403 - 2840

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