RogueRose
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I need a non or low compressible fluid, thicker than water, that isn't corrosive to brass
I need to us a fluid to hydraulically press out a part from a brass casing. The part is about .21" diameter and the cases vary in size and I use
different shafts that seal very close to the interior rim of the case. The problem is even with the close tolerance (about .0005 - .0015 tolerance
between shaft and ID of case.
There is enough clearance and enough pressure that the water is expelled from the case with high pressure, so I'm trying to figure out some fluid I
can use in place of plain water.
I add a little liquid dish soap to help make the shaft slide easier, but I'd like to have a thicker fluid that will not allow it to escape so quickly
under pressure.
I was thinking of adding something like glycerine to the water or maybe a salt solution - NaCl, KCl, CaCl2 or MgCl2, as the last 3 have very high
solubilities in water and I suspect it should make the liquid more viscous. I was also thinking ammonium sulfate as I know it makes a thicker
solution at higher concentrations but I'm pretty sure it will corrode the case as I've used this to dissolve copper before and have seen what it has
done to fittings to join tubing.
Can anyone think of a good salt or substance that would work well for this?
I guess maybe Na2CO3. I was also thinking about PEG (the laxative) that dissolves nicely in water, but IDK how soluble it is or if it would effect
the brass.
I would really like to stay away from oils b/c it will be a MAJOR PITA to clean them out afterwards, basically impossible.
Anyone have any suggestions of something that might work for this?
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Twospoons
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Boil some cornstarch in water. Just like thickening a stew. You can get anything from very runny to gel consistency, depending on dilution.
I've used this trick to thicken a homemade NaOH based paint stripper.
Helicopter: "helico" -> spiral, "pter" -> with wings
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Fulmen
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CMC is a very effective thickener, but high pressure liquids will leak no matter what.
I'm currently hydroforming sheet aluminum using rubber, and at 500-1000bar even that will start flowing through gaps less than 0,1mm.
We're not banging rocks together here. We know how to put a man back together.
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Sulaiman
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(cooking/vegetable/silicone/mineral/motor/gear/hydraulic) oil ?
CAUTION : Hobby Chemist, not Professional or even Amateur
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bobm4360
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If it needs to be water soluble for cleaning, corn syrup might do it. At the pressures we can generate, all fluids without entrained gases are
incompressible.
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RogueRose
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Quote: Originally posted by bobm4360  | | If it needs to be water soluble for cleaning, corn syrup might do it. At the pressures we can generate, all fluids without entrained gases are
incompressible. |
That makes sense and easy to get! I'll definitely try this out!
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RogueRose
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| Quote: Originally posted by Twospoons | Boil some cornstarch in water. Just like thickening a stew. You can get anything from very runny to gel consistency, depending on dilution.
I've used this trick to thicken a homemade NaOH based paint stripper. |
Another good solution , I'll try this as well and I've needed something for a thicker paint stripper before, so you gave me 2 solutions! Thanks!
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RogueRose
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I thought oil wouldn't work so well b/c then everything needs to be cleaned and cleaning oil from inside the casing will be difficult, but thanks for
the suggestion.
What happens if I add like 1pt dish soap to 3pt oil? Will the oil wash off much easier but remain the compressible qualities?
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RogueRose
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| Quote: Originally posted by Fulmen | CMC is a very effective thickener, but high pressure liquids will leak no matter what.
I'm currently hydroforming sheet aluminum using rubber, and at 500-1000bar even that will start flowing through gaps less than 0,1mm.
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IDK how easy I can get CMC but I'll look into it. I'm MUCH more interested in your hydroforming b/c I'm in the process of looking at hydroforming
after trying some vacuum forming - doing heated plastic. vacuum/hydro forming is pretty awesome, what pressures are you using and how large &
thick are the pieces you are forming? What kind of stuff are you making?
Do you do any metal working like milling and lathe work?
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Fulmen
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CMC is sold as a food grade additive, so it shouldn't be too hard to get hold of.
The parts I'm making are internals for a silencer (37mm in diameter):
these were made from 1mm aluminium (I've also made a couple in 0,5mm mild steel), first drawn into a cup before forming:
This is the forming die, the rubber (between piston and part) is omitted for clarity.
This is all homemade, most are in mild steel as it only needs to last for a few dozen parts. The drawing die is hardened as it's a pinch die that trim
the cup in one go.
[Edited on 28-4-20 by Fulmen]
We're not banging rocks together here. We know how to put a man back together.
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