I have a customer wanting to make a large ridged part and I'm
thinking a foam part would work good. I've searched groups google here
and found nothing.
I'm thinking the kind of process they use in the auto industry to
make the foam dash with the skin formed on it by baking the part. Does
anyone know the name of the process used to make these types of
foam/skinned parts.
I'm wondering what kind of molds are used and what foams can be used.

Ed Huesers
http://www.grandshelters.com

On Mon, 15 May 2006 09:48:38 -0600, Ed Huesers wrote:
I have a customer wanting to make a large ridged part and I'm
thinking a foam part would work good. I've searched groups google here
and found nothing.
I'm thinking the kind of process they use in the auto industry to
make the foam dash with the skin formed on it by baking the part. Does
anyone know the name of the process used to make these types of
foam/skinned parts.
I'm wondering what kind of molds are used and what foams can be used.

I saw on Mythbusters the other day, they were making foam molds. Was a
two-part mixture which they dumped into the form and it expanded. Think
"Great Stuff" only in bulk. I've seen it used in the construction
industry for spray-on insulation for housebuilding (wouldn't use it
myself, makes the walls impossible to work inside afterwards). Maybe
something like that would be an option? Forget the name of the foam but
someone here can probably come up with that.

Dave Hinz wrote:


snip

Was a
two-part mixture which they dumped into the form and it expanded. Think
"Great Stuff" only in bulk. I've seen it used in the construction
industry for spray-on insulation for housebuilding (wouldn't use it
myself, makes the walls impossible to work inside afterwards). Maybe
something like that would be an option? Forget the name of the foam but
someone here can probably come up with that.



This is reaction injection molding "RIM" molding. It is a thermoset
polyurethane rigid foam plastic. The two part process uses polyol and
isocyante are mixed and shot into a mold. I'm pretty sure the single
part stuff used to fill gaps in your foundation reacts with moisture in
the air to set.

It is a high part cost, low tool cost way of making foamed plastic
parts.

What is the application and how many parts does he want to make?

"Ed Huesers" wrote in message
...
I have a customer wanting to make a large ridged part and I'm
thinking a foam part would work good. I've searched groups google here
and found nothing.
I'm thinking the kind of process they use in the auto industry to
make the foam dash with the skin formed on it by baking the part. Does
anyone know the name of the process used to make these types of
foam/skinned parts.
I'm wondering what kind of molds are used and what foams can be used.

Ed Huesers
http://www.grandshelters.com

I've developed dozens of parts using the self skinning foam process. A
master is made from balsa wood, plaster, NC machined wax, whatever. Then a
two part mold is made from RTV Silicone (room temp. cured silicone) which
allows for really easy extraction of the finished part even when parallel
surfaces may be called for. There are many foam harnesses available and most
foam manufacturers are able to come up with the exact sponginess you need.
From really hard rubber like, to very light and soft. Once the tool is made,
you mix 1/3 hardener with 2/3 resin, stir like crazy for 15 seconds, pour in
the mold, quickly cover like in a clamshell, then put under a press as the
foam will immediately boil and exert huge pressures inside the tool. In
about five minutes you can demold, clean out excess flash, clean out the
bleed hole, and pour the next part. This, of course, is for low production
casting. As you can see, one part every 10 minutes or so.

My son is using Hydroseal Polymers Inc. 1215 Madera Way, Riverside Ca 92503
for the front foam bumper on his RCWindjammer www.rcsailcars.com --- I'll be
happy to send you some pictures of his process. Just email me.

"Ed Huesers" wrote in message
...
I have a customer wanting to make a large ridged part and I'm
thinking a foam part would work good. I've searched groups google here
and found nothing.
I'm thinking the kind of process they use in the auto industry to
make the foam dash with the skin formed on it by baking the part. Does
anyone know the name of the process used to make these types of
foam/skinned parts.
I'm wondering what kind of molds are used and what foams can be used.

Ed Huesers
http://www.grandshelters.com

These foams can be made with numerous different qualities. I made some foam
"projectiles" for my anti-tank gun that I made for paintball use. I got my
chemicals from Miltec inc. I can give you a phone number if you email me.

They mix the chemicals, and recommend operating parameters to give you the
results that you want. In my case, I was looking for a very dense, but soft
foam with a thin skin and a bright orange color so I could find them later
that could be poured at room temperature.

I made my mold from aluminum. I used dowel pins to line them up, and C
clamps to hold them closed. I made some test molds from wood, that worked
fine if coated with wax for release.

It's a UK company but look at this site.
http://spray-insulation.co.uk/product%20range.htm
It may give you some ideas.

John

On 15 May 2006 15:54:21 GMT, Dave Hinz wrote:

On Mon, 15 May 2006 09:48:38 -0600, Ed Huesers wrote:
I have a customer wanting to make a large ridged part and I'm
thinking a foam part would work good. I've searched groups google here
and found nothing.
I'm thinking the kind of process they use in the auto industry to
make the foam dash with the skin formed on it by baking the part. Does
anyone know the name of the process used to make these types of
foam/skinned parts.
I'm wondering what kind of molds are used and what foams can be used.

I saw on Mythbusters the other day, they were making foam molds. Was a
two-part mixture which they dumped into the form and it expanded. Think
"Great Stuff" only in bulk. I've seen it used in the construction
industry for spray-on insulation for housebuilding (wouldn't use it
myself, makes the walls impossible to work inside afterwards). Maybe
something like that would be an option? Forget the name of the foam but
someone here can probably come up with that.

It's polyurethane foam.
http://www.shopmaninc.com/foam.html

It differs from 1-part Great Stuff in two regards:
1. It expands more, about 30:1
2. It cures quite quickly and is not sticky once cured.

On Mon, 15 May 2006 09:48:38 -0600, Ed Huesers wrote:

I have a customer wanting to make a large ridged part and I'm
thinking a foam part would work good. I've searched groups google here
and found nothing.
I'm thinking the kind of process they use in the auto industry to
make the foam dash with the skin formed on it by baking the part. Does
anyone know the name of the process used to make these types of
foam/skinned parts.
I'm wondering what kind of molds are used and what foams can be used.

One other molding process not yet mentioned is rotational molding. The
"skin" can be (within limits) as thick or as thin as you want. Foam can
be done in the mold via a drop box to release a foaming agent after the
outer layer has formed. Or after de-molding with the same two part foam
others have suggested.
--
William

Thermoforming (vacuum forming) might do it. Molds could be aluminum, epoxy,
a material
called "die plank" or even wood.

I've worked with a sheet material that was a 3 part sandwich. Outer
vinyl-like skin, middle layer
of foam, back was a ABS or maybe PVC solid. Application was a cover for
dental chairs.
Stuff is tricky to form, but it can be done. Would probably be pretty easy
if the part is fairly
shallow.

IIRC, the sheet may have come from Spartech plastics.


"Ed Huesers" wrote in message
...
I have a customer wanting to make a large ridged part and I'm thinking
a foam part would work good. I've searched groups google here and found
nothing.
I'm thinking the kind of process they use in the auto industry to make
the foam dash with the skin formed on it by baking the part. Does anyone
know the name of the process used to make these types of foam/skinned
parts.
I'm wondering what kind of molds are used and what foams can be used.

Ed Huesers
http://www.grandshelters.com

How about structural foam molding? Its basically plastic injection
molding with the addition of nitrogen into the melt which allows the
melt to flow better in the mold. This allows you to create structurally
stiffer parts far more rigid than with traditional plastic injected
molding. An example of this would be the common rubbermaid utility
cart.

Ed Huesers wrote:

I have a customer wanting to make a large ridged part and I'm
thinking a foam part would work good. I've searched groups google here
and found nothing.
I'm thinking the kind of process they use in the auto industry to
make the foam dash with the skin formed on it by baking the part. Does
anyone know the name of the process used to make these types of
foam/skinned parts.
I'm wondering what kind of molds are used and what foams can be used.

Try www.artstuf.com

jk