Welding Thermoset Resins

Not in the way you melt thermoplastics together.

"thermoset means that after the resin has cured, usually with heat, it doesn't soften and melt.

Do you cast the parts?

Where's the seam?

Picture?

Describe your casting process.

Yep. Without further information, it would be hard. Thermoset means it does not change under heat anymore. Is there any solvent that you could use that "melts" the plastic parts interface? Some friends have reported very good results repairing car parts using methyl with this method. If not, maybe ultrasonic/vibration/friction welding? And, of course, you could also TRY laser. It does not seem to work, but laser is laser, plastic is plastic, thats an idea, and I'm sure a supplier would be glad to make a test for you. By the way, it seems that you're going to have some fun dealing with this issue.

Sorry, true thermosets don't respond to any of these processes.

MEK, methyl only works on thermoplastics. It will disolve thermoset resins used to "bind" the reinforcement fabric. If that is your process.

Are you pouring a liquid into a mold?

yep-going to have fun with this one - thanks-we are doing tests now and this is a rapid prototype company with 15 years under its belt- trying to figure out seam problems.

Are you pouring liquid into rubber molds?

Using stereolithography? Are you joining multiple cast parts together?

Is there reinforcement. Glass cloth? Can you eliminate the seams?

Why can't you use the parent material?

Good luck.

I doubt you can do welding of thermosetting plastics or resins if they are baked for specified time and temp,

The little hope is bake them partially, try some welding process and bake final part again.

Cyanoacrylate adhesives?

Thank you - I agree that the design of the seam(joint) is crucial to the result of the bonding and have argued that reasoning - The company is rapid-prototyping castings from UABS85 and similar materials using master SLA's. It is in the finishing process of the SLA's that the seam issue arises and is shown in the final casting... I had not considered the shrinkage of the adhesive during cure. I will now.

In the process of welding vinyl there is a lot of cleaning to do to clear away the excess vinyl at the seams. In order to increase production we have acquire CNC cleaners to do the job. I would look at casting in to the mould an edge that improves seam appearance. Maybe a little raise on one part that would over lap the actual seam and cover it with a finished edge.

Be aware that typical "thermoset" resins consis of crosslinked polymer chains, through primary bonds, whereas most physical properties of the thermoplastic resins are due to secondary bonding, crystallinity, etc. To melt or dissolve thermoset resins one has first to break the crosslink primary bonds, which usually means degradation of the polymer. Thermoset resins are best "welded" by the application of adhesives that will wet and adhere to the substrates being bonded. There are a number of suppliers for these adhesives, depending on the resins you want to bond, etc.