Suggestions for in-house rubber molding material (for prototyping)

BobM3 · Feb 27, 2017

I would like to mold some rubber pieces for prototyping. I'll make aluminum molds. The parts would be small (3-4 square inches). It would be nice if I could find a rubber-like material close to neoprene but it looks like the only stuff available is room curing silicone rubber. Any suggestions for material?

atomarc · Feb 27, 2017

Have you explored any of the Devcon castable urethanes. You can select your desired durometer by using their additives!

Stuart

implmex · Feb 27, 2017

Hi Bob:
My favourite is Dental Polysiloxane.
It's expensive but it comes in various consistencies in automix cartridges and sets in about 6 minutes.
It has poor tear strength, but it is very nice to use in almost every other respect.
I do most of my rubber prototyping with it but I usually make my molds out of Delrin.
Cheers

Marcus
Implant Mechanix • Design & Innovation > HOME
www.vancouverwireedm.com

j lewis · Feb 27, 2017

There are lots of urethane elastomers in different durometers that can be cold cast. Check Smooth-On website for ref. I used clear acrylic[plexiglass] for molds so I could watch the fill. Most were clear/amber or opaque/off-white, which I would tint with pigment to get the needed color. I did this to prototype sanoprene or neoprene parts. JinNJ

DMF_TomB · Feb 27, 2017

BobM3 said:
I would like to mold some rubber pieces for prototyping. I'll make aluminum molds. The parts would be small (3-4 square inches). It would be nice if I could find a rubber-like material close to neoprene but it looks like the only stuff available is room curing silicone rubber. Any suggestions for material?

.
.
polyurethanes are easy to do and usually just mix 2 parts and pour if a few bubbles not a problem.
.
release agent i use silicone spray or rub alcohol soaked rag on wax block and rub on part to coat with wax. or wax and spray silicone release agent. some release agents which work with other materials will cause polyurethane to not cure where it touched release agent. do not use petroleum jelly with polyurethane
.
i have made rubber metal parts and its better if rubber is through slots in metal or keyed in dovetails or tee slots. it sticks to metal but will peel off like electrical tape.

cg285 · Feb 27, 2017

what is it used for?

Steven-Canada · Feb 27, 2017

jewelry suppliers like RooGrande and Lacy tools have that stuff for molding and casting.

John Welden · Feb 27, 2017

+1 for Smoothon.

They have a lot of how to videos and their staff is very helpful.

snowman · Feb 27, 2017

John Welden said:
+1 for Smoothon.

They have a lot of how to videos and their staff is very helpful.

Yes, call them...they'll tell you exactly what product is going to be best for your situation. Further, I actually had one recommend a product they didn't sell, because none of their products would do what I was requesting. The technician that I spoke to had personal experience that was relevant.

moonlight machine · Feb 27, 2017

I just have Jackson Flexible Products mold parts for me, I make the molds and they do the actual molding. They can blend any type of rubber to get any durometer or chemical resistance you can think of.

cellardoor7 · Feb 27, 2017

Smoothon, great phone support, sample size quantities are available for experimentation. BCC Blehm is also good, prices are better than smoothon, less variety however.

DMF_TomB · Feb 28, 2017

polyurethane is not metal. just saying i had engineer wanted to fill missing metal with polyurethane or epoxy and it lasted all of 2 seconds
.
you get much over 1000 psi force and many plastics just break apart
.
http://theepoxysource.com/double-bubble.htm
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double bubble is small packets often only 2 tablespoons per packets used for small work. comes in all different sizes. for some jobs i had it do incredible work saving the cost of over $5000 in new parts made for $2
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usually you buy a box of the double bubble packets. advantage is a big container once opened stuff goes bad faster. small individual packets last longer cause each is sealed til you need to open

apt403 · Feb 28, 2017

What durometer? Neoprene can be had from 40 to 80 Shore A.

Gunna suggest reading this page:

http://lcamtuf.coredump.cx/gcnc/ch4/

Smooth-On makes good stuff, but Quantum Silicones makes some great products, more of an engineering-focused company, whereas Smooth-On seems to make a decent chunk of money on the artistic community - their 262F silicone was nice for what I was doing. Much pricier than Smooth-On stuff, though. And only sold through distributors. For what it's worth, the three places local to me that I contacted (all small operations) had very good knowledge of the product line off the top of their heads.

cg285 · Feb 28, 2017

so the op is actually not wanting to mold rubber but rtv instead, correct?
(i have to heat my mold)

robert123 · Feb 28, 2017

cg285 said:
so the op is actually not wanting to mold rubber but rtv instead, correct?
(i have to heat my mold)

Molding would imply shaping the material. I don't see a difference if vulcanization requires heat or if it occurs at room temperature.

garyhlucas · Feb 28, 2017

We needed a large v gasket about 11" in diameter. I spoke to a company that makes similar gaskets. We decided to try making a mold from the HDPE that we work with and bought urethane from smoothon. 7 inexpensive molds later we had a shape that works the way we want. The urethane parts turned out so well we are going to just mold the gaskets ourselves unless there are problems with chemical compatibilty. At about $3.00 a gasket though we can easily afford to simply replace them every so often.

avivz · Mar 1, 2017

You can try various Sikaflex products, that can be injected to the mold.

Johnny Larue · Mar 1, 2017

BobM3 said:
I would like to mold some rubber pieces for prototyping. I'll make aluminum molds. The parts would be small (3-4 square inches). It would be nice if I could find a rubber-like material close to neoprene but it looks like the only stuff available is room curing silicone rubber. Any suggestions for material?

yes I use it....it can be used in lieu of a 3D printer also since it doesn't even shrink .001....its for inspection and it makes hard rubber parts and then a mold can be made off them or sizes gleaned...its made by FLEXBAR.com....its called REPRO RUBBER.....greatest stuff since sliced bread...please make a note of it....LOL....this is the 2nd time now I have posted this....enjoy...it even does threads

BobM3 · Mar 2, 2017

Thanks for all the suggestions - very helpful!

M.C.E. · Mar 5, 2018

Hello, I just read this post and I'm surprised to see that this technique does not seem widespread in the US.
In Europe, this technique is widespread and technically approved by many big names in the industry.
Plastiform is marketed and distributed all over the world today.
Maybe this post is too old ;-)

Suggestions for in-house rubber molding material (for prototyping)

Cast Iron

Diamond

Diamond

Aluminum

Diamond

Stainless

Hot Rolled

Diamond

Diamond

Diamond

Cast Iron

Diamond

Cast Iron

Stainless

Stainless

Stainless

Cast Iron

Johnny Larue

Guest

Cast Iron

Plastic

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