Casting Urethane Rollers

[sdananay]

I am prototyping 5/8" dia urethane rollers for an aftermarket spare. I have successfully machined 70A durometer urethane but the machining process is too expensive to use in production. I plan to have a prototype mold made where I will cast the urethane onto bronze bushings. I am searching for a prototype material to try. Since the volumes are relatively low, the prototype material may in fact become the production material. I have several questions:
1. Does anyone have any source of prototype urethane? I do not have access to any special equipment such as vacuum degassers or curing ovens. All of the processing will be performed "ambient".
2. Does anyone have experience molding to oil impregnated bronze?
3. Can anyone suggest a resource for designing gravity molds?
Thank you in advance,
sdananay

 

[ornerynorsk]

I see two potential problems with what you are suggesting. Urethane really needs to be degassed before curing, and "good" urethane is heat cured. I have worked with RTV materials before, and they generally don't perform as advertised. In a former business of mine, I had a company called Western Roller in Bend, Oregon do all my urethane springs and rollers. They do fantastic work at a reasonable cost, they're experienced in insert molding, and mold costs are very minimal. Hope that helps you out. Another company came to mind called Polyurethane Products, couldn't find their info. Good Luck!

 

[patprimmer]

sdananay

What part of the world are you from

You could try Bayer, after all, they invented the stuff. They probably won't sell small volume, but might recomend a local user or reseller. Regards
pat

 

[sdananay]

I live just outside of Denver. I would like to find a vendor who could send me a small qty specifically for prototyping.

Thanks for responding,
sdananay

 

[ornerynorsk]

Here is a company I have bought from before, but like I mentioned in my previous post, you should degass and you should use heat-cure for the best results. A gallon kit will run almost $200.00 with shipping. Innovative Polymers Inc, 208 Kuntz Street, St. Johns, Mi. 48879 TOLL FREE: 800-340-4563 Phone: 989-224-9500 Fax: 989-224-1400