is a neat article on water
jets, showing 5 axis cutting.
But they comment that water jet cutting can be done with water alone, *without abrasive*, achieving much finer cuts. Abrasive cuts vary from .020
to .050, while non-abrasive cuts vary from .003 (!!) to .013.
When is non-abrasive cutting used? Often?
I would imagine it would be for thin and/or soft material.
What's the thickest material that can be cut with abrasives+water?
I was astonished to read that steel 24" thick can be cut with
oxyacetylene -- holy shit....
Water is usually used for non ferrous metals, sheet metals, many types
of hard plastics and what have you, under 1/4" thick. Adding the
abrasive REALLY increases the cutting power. And surprisingly..not all
that much abrasive is actually added.
Ive seen 4" thick aluminum on a BIG water jet table. No idea what the
max is.
And the kerf is surprisingly small. Though it takes a very special
torch and proper machinery to do it.
The pressures are awesome -- over 90,000 psi for the stronger units! holy
shit, I didn't know that was even possible.
That's proly one expensive effing pump....
Which suggests an upper limit to the psi for flood coolant -- too high and
you'd actually dull yer tooling, erode yer material!
I'll bet 5,000-10,000 psi is the practical limit for VMC-type coolant, proly
closer to 5,000.
I think some people here have 3,000 psi coolant -- that's some big-dick
machining, yo....
Pressure washers max out at about 3,000 psi, and they indeed can do a lot of
damage, house-wise, gouging wood, damaging shingles, like my asshole
neighbor does.
Fiberglass headliners in automotive applications. Worked really good for that.
Wes
--
"Additionally as a security officer, I carry a gun to protect
government officials but my life isn't worth protecting at home
in their eyes." Dick Anthony Heller
Talked to a business several years ago about getting some plate cut. Told
me about a 6" marble slab that he cut. Was sent oversize. Sent it back to
be recut or get it cut locally? He used his water jet. Said that the only
way he knew it was still moving during the cutting was to watch the monitor.
It was still cheaper then sending it back east to be recut.
We tended to use 0.005" dia diamond nozzles at 41,000 psi. We had a S-RIM
application
where we went to 0.008" and cranked the pressure up to 50,000 psi.
The only metal we cut were our waterjet fixtures ;) They tended to erode where
there were
dwells to make sharp corners.
Wes
--
"Additionally as a security officer, I carry a gun to protect
government officials but my life isn't worth protecting at home
in their eyes." Dick Anthony Heller
Sarah Lee. They use them for slicing the cakes in your supermarket freezer.
Also, insulation materials, fabric, and foil-thin metals, especially
aluminum.
I forgot about that one. Sarah Lee has a plant not too far away. I remember
the IR
representative talking about that.
Wes
--
"Additionally as a security officer, I carry a gun to protect
government officials but my life isn't worth protecting at home
in their eyes." Dick Anthony Heller
Steel cut to 24" - yes all of the time in the oil service manufacturing
companies.
It is great to go the the scrap yard in town and see the CNC cut scraps!
They await the oxygen lance as the other methods just can't get there
when done by hand (heat and gas cost).
Martin
Existential Angst wrote:
Well, let's see...
The granite under Niagara falls is 250 feet high, and it gets worn
away by something like a foot per year.
The Grand Canyon is about a mile deep, and it was cut entirely by
water, and the bits of rock and sand the water carried with it.
So the answer is, you can probably cut just about any thickness, and
just about any material. The only technical problems to be solved are
precision and production rate.
Stay tuned.
KG
This is sorta related, and might be of interest. Where I work, we
do a lot of micro-sand-blasting. Tiny nozzles, and very fine grits
(down to baking soda and talcum powder, literally) for very precise
deburring of small parts, and very consistent control of surface finishes.
It works well; but it's a PITA. Even with vacuum systems, and
enclosures and containement and all the rest, we still deal with the
grit getting where we don't want it. And in a precision machine shop,
grit of any kind is bad news.
So there's been some talk about a new process: dry ice blasting.
The equipment makes dry ice, pulverizes it according to the desired grit
parameters, and then uses is (quickly, I'd guess) just the way we now
use powders and glass beads. And after the sharp, hard little ice
crystals have kamikaze'd into the work, and have done their jobs, they
just evaporate, and are wisked away by relatively small and simple
vacuum systems that don't need filters or baffles or cleanounts, or
anything else like that.
The instant I heard about it, it made sense, and I kicked myself
twice because I didn't think of it.
KG
1 foot per year? Heh, I think at that rate, over geologic time, we'd be
down to china by now.
Mebbe a fraction of an inch per year?
Don't forget, the water is falling *into water*, which is essentially
coating the granite. The only thing eroding after the pools build up any
depth is the flowing water itself, which is proly .001" per year, on solid
granite.
But the overall point is legit. Sheeit, wind can erode stuff....
We used dry ice blasting for cleaning built up mold release on our srim forming
tools.
Worked fantastic.
Wes
--
"Additionally as a security officer, I carry a gun to protect
government officials but my life isn't worth protecting at home
in their eyes." Dick Anthony Heller
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