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Water Jet - wtf ??
Macbeast - 21/8/08 at 08:32 AM

Could someone explain to me how a waterjet cutter works ? I read about waterjet cutting of metal an even glass.

Also what is CNC pls ?

I must have been off school the day they did kit car fabrication

mistergrumpy - 21/8/08 at 08:34 AM

I think water jet is a high pressured jet of water which contains sand as the abrasive and therefore cuts through the material.

Project7 - 21/8/08 at 08:45 AM

CNC - Wiki explains it better than i can

http://en.wikipedia.org/wiki/CNC

BenB - 21/8/08 at 08:52 AM

High pressure water alone will do the trick. On submarines if a pressure pipe burst the room would often fill up with steam so much you couldn't see where the problem was. If you used your hand you risked chopping it off. Apparantly the old trick was to hold a broom in the air and slowly walk around the room. When the head of the broom fell off you'd found your leak....
Nice story- not sure if it's true!!!

loggyboy - 21/8/08 at 08:56 AM

Some water jet cutters dont use abrasives, they just use the sheer force of the high pressure water. Its quite easy to appreciate if you think how much damage a simple home pressure washer can do to plastic and wood.

Wikis good for waterjet info too:

http://en.wikipedia.org/wiki/Water_jet_cutter


** beaten too it spent too long finding link!

[Edited on 21/8/08 by loggyboy]

iank - 21/8/08 at 09:10 AM

Here's some information from a manufacturer of the machines - both water only and water+abrasive.

http://www.waterjetcutting.co.uk/

At 55,000 psi (3930 bar) not much can resist.

02GF74 - 21/8/08 at 09:55 AM

quote:
Originally posted by BenB
High pressure water alone will do the trick. On submarines if a pressure pipe burst the room would often fill up with steam so much you couldn't see where the problem was. If you used your hand you risked chopping it off. Apparantly the old trick was to hold a broom in the air and slowly walk around the room. When the head of the broom fell off you'd found your leak....
Nice story- not sure if it's true!!!


probably has some factual basis behind it.

Mr Ward, out metalwork teacher told a similar story about a boiler type thing. It spring a leak and you could see a thin water jet. Someone decided to put their hand in the stream and subsequentlly got a hole in their hand resulting in having to have it amputated.

If it can go though solid steel, aluminiumj, human flash and boone is not going to challnege it.

scootz - 21/8/08 at 09:58 AM

As someone who once used a pressure washer to clean some cack off the toes of my wellies, I can vouch for the power involved... I still have the 1" scar below my big toe to remind me!

aerosam - 21/8/08 at 09:59 AM

We have a progressive technologies waterknife machine in work. It's about the size of a house and is CNC controlled. We can vary the pressure and abrasive content of the water to either strip coatings, (plasma, paint, rubber, adhesives etc) or completely cut through stuff.

It'll cut through pretty much anything.

Macbeast - 21/8/08 at 10:06 AM

Thank you all very much All is clear.

I find it difficult to imagine a jet of water cutting through titanium but I suppose if it were hard water ....?

Minicooper - 21/8/08 at 10:13 AM

They were and still are used in the shipyards, watching it cut 6 inch plate with ease was quite something

Cheers
David

the_fbi - 21/8/08 at 11:54 AM

quote:
Originally posted by BenB
On submarines if a pressure pipe burst the room would often fill up with steam so much you couldn't see where the problem was. If you used your hand you risked chopping it off. Apparantly the old trick was to hold a broom in the air and slowly walk around the room. When the head of the broom fell off you'd found your leak....
Nice story- not sure if it's true!!!

Totally true, the issue was that it was actually superheated steam rather than water which came out of the pipe, hence invisible.

nick205 - 21/8/08 at 03:54 PM

CNC = Computer Numerical Control

Basically a programmed computer is used to precisely control the movement of the tool and/or workpiece via stepper motors, hydraulics etc.

Watch this you tube vid of a W16 engine block being machined from a solid billet for a stunning example of what modern machinery can do...

http://www.youtube.com/watch?v=GU32Q6QXtWQ&feature=related

scotlad - 21/8/08 at 04:13 PM

The mop story is true though the last time i saw one it was a jcloth on a broom handle. Used for finding superheated steam leaks near power station steam turbines- you can hear the leak but cant see it as its at around 568 celcius and 160bar pressure therefore its the steam is too hot to condense and become visible until its cooled somewhat.

[Edited on 21/8/08 by scotlad]

zilspeed - 21/8/08 at 05:22 PM

Regarding waterjet cutters. AndyW7de of this parish has one.

nick205 - 22/8/08 at 11:56 AM

quote:
Originally posted by zilspeed
Regarding waterjet cutters. AndyW7de of this parish has one.


An online parish - now there's a thought

Vindi_andy - 29/8/08 at 03:29 PM

There was a guy where my dad used to work who lost his arm just below the elbow thanks to a pinhole in a high pressure hydraulic line. Basically he didnt see the stream as the hole was so small waved to a colleague on the other side of the yard and his arm crossed the stream.

MikeRJ - 30/8/08 at 11:44 AM

quote:
Originally posted by Vindi_andy
There was a guy where my dad used to work who lost his arm just below the elbow thanks to a pinhole in a high pressure hydraulic line. Basically he didnt see the stream as the hole was so small waved to a colleague on the other side of the yard and his arm crossed the stream.


I presumed it had to be amputated due to poisoning by the hydraluic fluid rather than it cutting his arm off? That is one of the dangers of high pressure hydraulic systems.

britishtrident - 31/8/08 at 07:28 PM

quote:
Originally posted by BenB
High pressure water alone will do the trick. On submarines if a pressure pipe burst the room would often fill up with steam so much you couldn't see where the problem was. If you used your hand you risked chopping it off. Apparantly the old trick was to hold a broom in the air and slowly walk around the room. When the head of the broom fell off you'd found your leak....
Nice story- not sure if it's true!!!


You are thinking of a high pressure superheated steam leak --- you can't see superheated steam it is to most intents and purposes a gas and completely invisible. The only warning you get is the noise. Wander past a high pressure superheated steam leak and it can instantly cut you in two.

Big steam ships were just the dogs danglers

[Edited on 31/8/08 by britishtrident]

Vindi_andy - 1/9/08 at 12:42 PM

quote:
Originally posted by MikeRJ
quote:
Originally posted by Vindi_andy
There was a guy where my dad used to work who lost his arm just below the elbow thanks to a pinhole in a high pressure hydraulic line. Basically he didnt see the stream as the hole was so small waved to a colleague on the other side of the yard and his arm crossed the stream.


I presumed it had to be amputated due to poisoning by the hydraluic fluid rather than it cutting his arm off? That is one of the dangers of high pressure hydraulic systems.


I believe it was the fluid that cut his arm off but I could have misheard the story from my dad.