Removing soils after hot wash

[dfarning]

I am looking for advice on removing soils, grease, and other gunk from complex castings after hot soaking. Currently, I am hot soaking antique automobile engine components at 110F in a degreaser for about 24 hours to remove the gunk.

This softens up the soil enough that it can be brushed off with a nylon bush. My problem is that it is extremely time consuming to clean out each individual crevice. There are also places the brush can't get to. Does any one have any advice on mechanically removing the soils and grease?

I have tried drying the part after soaking and then bead blasting. By the time the soils are brittle enough for the bead to remove, the soils have firmly reattached themselves to the part(:

I am currently attempting to follow up the first soak with a second dip in boiling cleaner to see if the formation of bubbles against the part will remove the gunk.

David

[pickleboy]

it may take some thought and work but the 2 main components that you are missing is agitation and high pressure jets. think of a hot tub for degreasing. that way the dirt and crud is softened and then blasted away. i am good for thinking up this stuff but how to construct it you are on your own. i would however be very interested in what you or others may come up with.

[dfarning]

I agree the aggitation is the key. The cleaner alone just seems to lift the top most layer of gunk. Running the recirclulation pump seems to help by always keeping fresh cleaner in contact with the gunk.

I wonder if could hit it with spray from with a pressure washer. It would make a heck of a mess.

I am going to try looking at ultrasonic cleaners. I am running into the same problems removing the smut, black rust, after electrocleaning the part to remove any oxides.

David

[jrow]

dfarning,

Like pickleboy says a pressure washer would work great but would be messy. Have you tried a fine rotary wire brush? I have some that are 1 1/2" in diameter up to 3" in diameter. Another wild thought would be to use a sump pump, neck the outlet down and use that as a pressure washer! The pumps should be available at a good hardware store.

John

[dfarning]

I got out a crock pot to run some tests on how temperature would affect the cleaning rate. I came up with some surprising results.

I was thinking of cleaning as a chemical reaction where every 10C (about 18F) increase in temperature would double the reaction rate. Thus 4 hours at 110F would be about the same as 2 hours at 130F....

Instead, I found that with my cleaner and soil/grease combination there was a critical temp, about 145-150F. Above this temperature the cleaning/degreasing happened very quickly. In less than 30 minutes the cleaner would disolve through about 1/8 inch of gunk. Where the gunk was, there would now be a clean pile of sand/dirt that would rinse off with flowing water.

I wonder if it has something to do with the viscosity of the oils or greases involved or if it has more to do with the cleaner?

David

[pickleboy]

what you are finding is the principal of the old hot acid tanks that were used for years in the auto machine shop industry. commonly called vats, they contained some kind of acid at around 150-200 degrees, the part was submerged and agitated(shook) back and forth. this would result in a completely clean part in about 4 hours, for say an engine block. then the part was rinsed and was ready for machining and rebuild. due to environmental concerns with the acid and waste product this type of cleaner is now almost extinct. in place of that there are automated washers that will suspend the block and use water based cleaner at high temp. the part is rotated and there are high pressure jets in the enclosure that blast the crud off at hundreds of psi. these new machines are great but very expensive. as for your project if you can devise a way to create a jet nozzle that can spray this heated cleaner under the liquid level of the tank it should help give the agitation that is needed. it would need to be faster than a recirculating filter system. maybe in the 75-100 gallon per minute range. hope this helps and i didnt bore you.

[dfarning]

I am using a aqueous cleaner that is safe. I called county hazmat guy, he said said I could drain into the city sewage system but not the storm system. He would also take my disposable filter cartridges for free.

Yes it seems you have to move large amounts of water to run the underwater jets. Pumps are of 10+ hp.

I'll just run at a higher temp until I can justify a more expensive system.

David

[fly]

The old time acid was caustic, and if you keep the temp. around 175, you should be able to get what you need. I have a chemical from ABright and I run the temp. at 175, but the parts mainly have just compound on them but Abright says that the solution will work on all dirt, oil and grease deposits..Do you have the sp degreaser from caswell....

[sswee]

FYI - I still have and use a hot caustic vat for cleaning engines and steel components. The caustic used is primarily composed of Sodium Hydroxide. The powder comes in a 35gal drum. The vat is heated and circulated by a motor hooked to a shaft into the solution with a prop on the end.
SS

[dfarning]

I am working on parts that are made of zinc die-cast and cast iron. I put a piece of cracked pot metal in a lye (I think that is basically Sodium Hydroxide or was it sodium Nitrate. I think I should have listened better in chem class. Who would have thought it might come in handy someday.) solution of 1 cup per 5 gallons of hot tap water. I do belive the lye attacked the die-cast faster than it attacked the contaminants on the metal's surface. The part looked like someone took a shot gun to it;(.

David