How to Dissolve Burnt Plastisol (to Clean Inside of Heat Exchanger)?

[jfxberns]

We've been running the same heat exchanger on our soft plastic injection machine for a few years. We recently pulled it to refurbish (clean, replace heaters and thermocouples, re-run wiring etc.) and found there there was a lot of brown/black burnt (baked on) residue inside the heat exchanger.  (Probably plastisol, but it could be from colorants or glitter.)

It's pretty hard, I don't want to ream it out (I want to keep the plastisol channels smooth), so I was hoping someone here had some experience on how to soften the burnt plastisol so we can remove with a non-abrasive brush. 

 

Have you had a similar problem?  How did you fix it?

[mark poulson]

If your machine has Teflon seals, acetone should dissolve any crud.

[jfxberns]

3 hours ago, mark poulson said:

If your machine has Teflon seals, acetone should dissolve any crud.

We've removes the heat exchanger block itself, it's just a slab of aluminum at this stage.

I was going to try to try acetone as I know it dissolves plastisol and PVC, but I was wondering about anyone's experience removing the burned stuff. 

Have you tried on burned plastisol?

[rcbv]

No experience with burned plastisol but I would soak it in acetone and then try using a tooth brush or nylon scrub pad to see if the burned material is softening. If it is, then continue soaking and scrubbing.

If it's really stubborn then you might have to use more aggressive mechanical abrasives like steel wool or wire brush. 

 

[jfxberns]

For future readers: I tried acetone, it cleaned the gunk on the channels, but it didn't soften the baked on crud at all.

I ended up paying out mold maker to ream the channels.