Dry Ice media blasting?

I was reading an older issue of one of the Euro car mags I have and there was a short little article on, basically media-blasting parts with dry ice. The positives were no dust to clean off, no solvents to hurt the environment. Seemed pretty cool to me. Anyone ever heard of this?

Yes, but they were cleaning mold off wood. All that was left was a fine sawdust. I can't see ice crystals being abrasive enough for metal work, but who knows?

Ditto. My understanding is the dry ice doesn't 'blast' material off so much as flash-freeze it, which causes material to break adhesion to the sub-surface. This would probably work well for heavy de-greasing, but not so well for rust removal.

Did a quick search. Some cool stuff http://www.youtube.com/watch?NR=1&v=l_9nITRz--0

The article I read mentioned they removed ink from a page without hurting the paper! I agree, not sure if it'd remove rust, but it did a good job on that paint.

They use it on Vette's as it is said not to harm the gell coat. We rented one here to try and clean on of the CNC polishers (Optics grinding) that had allot of slurry build up. It worked but not as good as we hoped we had best luck if we weed burnered the area 1st to maximize the thermal shock.
Theres a plastic media that they use on fiberglass too.

In reply to 44Dwarf:

slurry? What do you use for the "liquid" in a dry ice slurry?

I had thought that the dry ice method was all crystal CO2, and not with a carrier (I can't remember the technical term for that in a slurry).

In reply to alfadriver:

I think what he means is the lubricating compound between the polisher and the optics, which would leave residue on the machinery after awhile.

The dry ice method is literally that: dry ice crystals blown at the work under pressure. When the ice hits the dirt, it goes directly from solid to gas, getting the required heat from the dirt, causing it to quickly contract and break away from the work.

In reply to Ian F:

where can i find a face palm smiley. Totally misread that.

I was trying to picture a liquid at solid CO2 temps.... couldn't figure one out.

Thanks.

alfadriver wrote: In reply to 44Dwarf: slurry? What do you use for the "liquid" in a dry ice slurry? I had thought that the dry ice method was all crystal CO2, and not with a carrier (I can't remember the technical term for that in a slurry).

We use the slurry as the carrier for the abrasive we polish the lenses with. It flings against the walls and we are left with a build up to lens materials on the walls.

The blasting is done dry with just ice beads. It comes in large toats from the place we rented the blaster from. The blast needs a crap load of air the one we used needed a 1.5 ID inch hose. We ran a Sulair twin screw compressor.

Where I used to work we had a unit to blast mold release off of molds used for making automotive seat foam. It actually cleaned the molds too well and we had to go to other cleaning methods. The maintenance guys still have the unit and use it for cleaning all kinds of equipment. It doesn't leave a lot of dust because the media evaporates, but it does pulverize whatever you knock off your work piece really well.

We used it to clean the wood mat particulate and resin off of the compression molds at my former place of employment. According to the sales guy it is a flash freeze and abrasive effect. Worked very well for our application

44Dwarf wrote: Theres a plastic media that they use on fiberglass too.

I had a car plastic media blasted once. It did a great job of removing the paint, but it gets everywhere and it's nearly impossible to clean it all up...that was around 15 years ago, and I still have little plastic beads falling out of nooks and crannies.

stuart in mn wrote:

44Dwarf wrote: Theres a plastic media that they use on fiberglass too.

I had a car plastic media blasted once. It did a great job of removing the paint, but it gets everywhere and it's nearly impossible to clean it all up...that was around 15 years ago, and I still have little plastic beads falling out of nooks and crannies.

That's the most compelling thing behind the dry ice. With other media, and with dipping, you're going to end up with crap in places you don't want it and can't get it out.

I've used dry ice blasters before in a prior job. They will not remove paint or non-loose rust. They do an excellent job of removing ink, grease/grime, etc. They will not remove anything that is really bonded to the metal like rust or paint. We used them to large printing presses and auxilliary equipment.

alfadriver wrote: I was trying to picture a liquid at solid CO2 temps.... couldn't figure one out. Thanks.

Off the top of my head, you could put the dry ice in a bath of liquid nitrogen. Now THAT would be a cold Slurpee.