Why waterjet? Why not OILjet?

Cheeseking said:
I may have missed the reason you’re wanting to use oil vs water. Is it due to corrosion of the parts or machine???
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Being a DIY machine, it would be made mostly from the cheapest off-the-shelf components available. The pump would likely be a repurposed pump, originally designed & sold for purposes other than waterjet cutting. Pressure washer pumps get me to about 4,500 PSI but if I want to go higher than that, all I find are hydraulic (oil) pumps. So say I find a 10kPSI hydraulic pump, is it better to reinvent the pump to move water without prematurely failing, or is it better to reinvent the process to use oil instead of water? The second half of that question is what I'm exploring.
 
Flammable or inflammable? Are they the same thing? LOL Sounds like a George Carlin routine- "down the tubes!" What tubes?
 
Oil is a lubricate and would not be efficient at cutting. And a high pressure hydraulic pump needs the heavy weight oil to achieve the pressure.
 
Guys the water in most cases is not doing the actual cutting. Abrasive media (garnet) is entrained in the stream in the cutting head, post orifice, before it enters the silicon carbide mixing tube. The sharp garnet particles are what cuts the material. That said many softer materials like rubber can be cut water only.
 
Flammable and inflammable do not mean the same thing. If something is flammable it means it can be set fire to, such as a piece of wood. However, inflammable means that a substance is capable of bursting into flames without the need for any ignition. ... The opposite of both words is non-flammable.
 
Why do you think oil would have such and advantage? It is not particularly difficult to design a waterjet using water. Stainless hardware is not ridiculously more expensive than regular steel when building from scratch. I guess for a hobbyist, trying to adapt a hydraulic pump it might make some sense but for industry, no. BTW there are lots of low viscosity organic fluids you could try other than conventional oils. As discussed, flammability is the major issue. I suppose you could go with PCBs but I would not recommend it! I can just imagine aerosolized PCB all over the shop.
Why don't you try using a hydraulic pump to pump water with a corrosion inhibitor? Think water soluble coolant.
Robert
 
Cheeseking said:
Guys the water in most cases is not doing the actual cutting.
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Not necessarily, we did downhole under reaming using plain water at 10,000 psi. It would cut through rock concrete and steel with no problem. One time the nozzle got stuck in the whipstock and cut the whole end of the whipstock off.
 
rwm said:
Why do you think oil would have such and advantage? It is not particularly difficult to design a waterjet using water. Stainless hardware is not ridiculously more expensive than regular steel when building from scratch. I guess for a hobbyist, trying to adapt a hydraulic pump it might make some sense but for industry, no. BTW there are lots of low viscosity organic fluids you could try other than conventional oils. As discussed, flammability is the major issue. I suppose you could go with PCBs but I would not recommend it! I can just imagine aerosolized PCB all over the shop.
Why don't you try using a hydraulic pump to pump water with a corrosion inhibitor? Think water soluble coolant.
Robert
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It isn't just rust that worries me. It's my understanding that hydraulic pumps are lubricated by the oil flowing through them. I believe hydraulic pumps often have metal-on-metal moving parts in areas where a water pump would have metal-on-seal or metal-on-bushing. And further it's my understanding that waterjet pumps are so expensive because of the special seals and bushings required; seals and bushings that a hydraulic pump doesn't have, and doesn't need.

[My understanding] could be way off.
 
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