Questions about making a mould.

[fbdesigns1]

I'm in the process of making a mould off of a product.

The problem is that, the product I have, was done with a final coat of primer, and not knowing too much about resins.. I went ahead and started making a mould off of it. Things were goinig smoothly until the resin started eating away the primer and my past 2 weeks of work went to nothing.

What would you guyz recommend to have as a final coat on the product, that I'm making a mold off of?? something that's tough enough to sustain resin but is easily available?

thanks.

p.s. I'm using polyester resin if that makes any difference.

 

[kenvlach]

Sounds like you are using one part repetitively as a pattern. Not knowing the size or part material, I will offer 2 possible solutions:
1) If the part is metal, strip the finish and have the part electroless nickel-plated or PTFE (Teflon®) coated.
2) If the part is a non-metal, make a replica: spray lube the part, make a plaster of Paris cast (with wax paper parting lined if necessary), then use the plaster-of-Paris as a mold to cast an aluminum part. Sand if necessary to allow for coating thickness if tight dimensional tolerances. Then have the aluminum coated with PTFE or EN.

Hope this helps,
Ken

 

[fbdesigns1]

the part is 8"x8"x2" and is made out of plastic. Its an car interior part. Since it had texture on it, I went ahead and used filler primers to make it smooth.

thanks for the advice Ken but now it raises more questions for me. Since later on, I'm planning on moving towards making exterior body panels, such as front bumper covers and so on. Would I still have to go through that steps you described? or is there any other way of doing that.

Later on most of my products are going to be carved out of modeling clay or foam and then sealed and primed. there must be some other way than making a duplicate cast aluminium part. And using that to make a mold off of.

Thanks for the help, I appriciate it alot.

 

[kenvlach]

Still not certain what you are doing. Too labor intensive, are you making hand laid up prototypes?
I am not a mold maker although many moons ago did cover such in college. My company does coatings such as EN of molds for both injection molding (with lots of abrasive filler) & hot press molds for SMC (sheet molding compound).

I suggest a book such as Plastics Engineering Handbook for mold making.