water jet cutting

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Member
Joined
Feb 16, 2015
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17
Location
south africa
Good Day everyone ,
Are there any issues having parts in aluminium cut with a waterjet . The reason I ask was that I was told that the water jet may ingrain some garnett in the edge and that could be the start of a stress crack . Any thoughts.
 

PiperCruisin

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Jan 17, 2017
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Idaho
I think any cutting method can create an edge imperfection that can initiate a crack...even the sanding you do after to clean it up. Waterjet is probably one of the cleanest. You can clean it up the edge to get rid of the abrasive. Usually the problem with the abrasive is it can eat up you tooling if it is machined after waterjet.

I would concentrate more on the design.
 

rv6ejguy

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Jun 26, 2012
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Calgary, Alberta, Canada
Sanding or a 3M disc is a recommended way to reduce the chances of of edge crank propagation on steel or aluminum parts which are sheared, saw cut, WJ, plazma or laser cut. Not a step I'd skip on critical parts. The microscopic scratches from this process run 90 degrees to the stress risers texture present from most cutting processes.
 

quickcut

Member
Joined
Feb 16, 2015
Messages
17
Location
south africa
Yes I will certainly polish the edges. I have a leather and scotch brite buffing wheel , followed by a quick check under a magnifying glass , I think that should do the trick. thanks
 

ScaleBirdsScott

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Feb 10, 2015
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Uncasville, CT
I've gotten some really rough waterjet parts, and some really nice waterjet parts. Basically the difference between a big fab shop that is used to blasting out heavy plates on the machine in their grimey warehouse vs a dedicated machine shop that does small detailed parts and a more considered environment. Definitely talk to them about what kinds of finish you can get and see if there's a protective film or similar setup possible, because that rough one I got back was done with no film and had a very fine misty sort of blast effect from overspray being kicked back up. (You could see untouched areas that were masked by the slat bed.) Thankfully, the parts were for a load test so I wasn't too concerned about any impact on longevity of those parts, but it did tell me not to use that source for anything that might fly.

I've been curious as of late at switching away from waterjet and CNC router made parts, and instead going for laser cut parts; and have similar concerns about the HAZ from a laser cut part as one might have with the edge finish from waterjet or other process. I know plenty of kit makers are using laser, and so it can't be too terribly hard to deal with if it's a concern at all.

I think in general the basics are simply "clean up the edge" regardless of how you cut the gross shape.
 

TFF

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Apr 28, 2010
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16,181
Location
Memphis, TN
Commercially it’s about speed and cost. Is it cheaper to waterjet and hand finish the parts or mill with little after work. Do you pass the work to the builder or want to deliver no work required?
If you just want to make one set, mill it. Your own equipment will probably be mill. If you have to make 40 and then 40 and then 40... you will go with the financial. The gains start to kick in.
 
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