Flat sanding cast aluminum

[Mulboost]

Good evening Practical machinists,

I am looking for a good solvent to keep 80 grit sandpaper from getting clogged with aluminum deposits from cast aluminum. My remanufacturing process requires flat sanding valve body castings on a slab of granite with 80 grit sand paper (affixed to the granite with clamps). I have fabricated a fixture to contain the granite slab and contain a solvent of some sort. There is a sump, filter and pump to keep a stream of solvent circulating over the sandpaper to "carry away" the deposits.

What would be recommended as a "healthy" low volatility solvent to keep in the open bath?

I emphasize wearing respirators whenever in these scenarios, but my advice only goes so far. Even though the PPE is provided, it is not always used by my technicians.

I was thinking mineral oil and used parts solvent, but I am open to any recommendations. We are using a metal gerotor style pump and ~5 micron hydraulic filter.

Thanks!
John

 

[eKretz]

Solvent as in Stoddard solvent, or basically mineral spirits? That will probably work well but it's not good to be getting on hands and breathing all the time - could cause long term damage to people. I'd make sure to enforce the use of the PPE if you're going to be using that, especially used solvent with who knows what dissolved in it.

You might also try plain old WD40. I've found it a pretty good lubricant for aluminum work - to include lapping. You could add a little light mineral oil if you need an increase in viscosity also.

 

[Nmbmxer]

What kind of valve body? Cosmetic or are you trying to correct the surface?

 

[memphisjed]

Band-aid by Lennox? Water based saw coolant, more of a non foaming soap.

 

[Ries]

The type of sandpaper really makes a difference.
On Aluminum, I do as much heavy removal as I can first with the brown grinding discs from Rex Cut. I have never found anything that works as well for grinding aluminum in a 4 1/2" grinder.
When I have spot sanding to do, I use Klingspor alumina zirconia flap discs.
For smoothing large surfaces, I use the cloth backed velcro PS33 discs from Klingspor on my random orbit sanders. I generally keep em in stock from about 50 grit up thru 150 grit. They last a long time and dont load up.

 

[Mulboost]

What kind of valve body? Cosmetic or are you trying to correct the surface?

They are cast aluminum automatic transmission valve bodies. Essentially a Chrysler 727. Correct the surface.

 

[Mulboost]

Solvent as in Stoddard solvent, or basically mineral spirits? That will probably work well but it's not good to be getting on hands and breathing all the time - could cause long term damage to people. I'd make sure to enforce the use of the PPE if you're going to be using that, especially used solvent with who knows what dissolved in it.

You might also try plain old WD40. I've found it a pretty good lubricant for aluminum work - to include lapping. You could add a little light mineral oil if you need an increase in viscosity also.

We are currently using WD40, it’s working pretty well (has cleaning qualities as well as a little lubriicity), but I am worried about it getting aerosolized /inhaled.

Could we use mineral oil? The main thing we want to avoid is clogging the aluminum in the sandpaper,

 

[eKretz]

We are currently using WD40, it’s working pretty well (has cleaning qualities as well as a little lubriicity), but I am worried about it getting aerosolized /inhaled.

Could we use mineral oil? The main thing we want to avoid is clogging the aluminum in the sandpaper,

If you can find a light enough viscosity I don't see why not. Try some baby oil, it's generally a very light mineral oil. If that works, call a bulk supplier.

 

[Dan from Oakland]

Kerosene?

 

[majohnson]

WD40 is want I used for over 30 years of rebuilding automatic transmission. Just spray more WD40 on the paper and blow out the particles. On your granite are you sure it flat? Granite will wear we used 1/2” plate glass.

 

[Strostkovy]

I use IPA when countersinking or tapping aluminum, so I would expect it to work well for sanding. Probably does not solve any of your concerns though.

 

[Peter from Holland]

Plain water
I would try that first

Peter

 

[Overland]

I use IPA when countersinking or tapping aluminum, so I would expect it to work well for sanding. Probably does not solve any of your concerns though.

Like India Pale Ale ?

you don't like the job, so you've turned to drink ?