question about water jet cutting

Think of a regular sandblasting nozzle, often made from a hi-tech ceramic. They do get eaten away, but the machines are designed to pass the water and abrasive through as frictionlessly as possible, and of course the jet is nearly perfectly perpendicular to the metal being cut so it's very abrasive there.

GWE

The nozzle has an orifice made of either sapphire, ruby or diamond which the water passes though and then a venturi draws the abrasive into the stream and it is mixed in a ceramic tube.

Because the nozzle is made of ceramic. harder than the media. However..it too does get worn after some useage.

Gunner

"I think this is because of your belief in biological Marxism. As a genetic communist you feel that noticing behavioural patterns relating to race would cause a conflict with your belief in biological Marxism." Big Pete, famous Usenet Racist

Yep! If you want to see a good example of that, although not water jet cutting, use a blast cabinet with aluminum oxide media, with a ceramic nozzle. Life is short. VERY short. A carbide nozzle, by sharp contrast, will last for months on end. Nozzle must be harder than the abrasive.

Harold

It does wear, but slowly. There are a few things that keep the wear down to a minimum:

#1 - Extremely tough mixing tube material #2 - Nozzles are designed such that they simply guide the medium in a straight direction, with as minimal side impact as possible. (one of the key tricks in making a good nozzle) #3 - The abrasive used is usually garnet, which although is very hard relative to most materials, is reasonably soft compared to the nozzle.

A typical nozzle will last between 20 and 80 hours of cutting, depending on things like pressure used, amount and type of abrasive used, the design of the nozzle, and when you consider it worth thowing out (for precision, throw it away early, but if your' just hacking, you can often get a few more hours from it.).

If you are cutting things that are way harder than metal (like some ceramics), then you might use an exceptionally hard abrasive (such as a hard ceramic). In this case, the nozzles wear out quite quickly (maybe

10 hours or faster). However, the process may still be worth doing because there may be no other way to do the job. I see this in some aerospace applications, for example.

- Carl

peter wrote: