WaterJet Cutting
technology is an alternative to traditional plasma and laser manufacturing and machining approaches. It is a high speed low cost cutting solution that uses pressurised water at up to supersonic speeds to cut through almost any material.
Using water to cut steel, wood and rock, while a relatively new concept in manufacturing, makes good sense as it provides an environmentally friendly solution to cutting problems. The process is clean in so far as it does not leave dust, grindings or chippings as waste and does not cause any chemical air pollution. The water carries away most of the waste in a form that can be handled economically and with minimum impact to the surrounding environment.
History of waterjet cutting
The idea of using water to beat or erode materials is not new. Low pressure jets of water were used for mining gold in California in the 1850s.
While modern waterjet cutting has evolved from a solution used by the aerospace industry to cut exotic alloys, it was originally developed by Dr. Norman Frantz (often dubbed "The Father of waterjet cutting"). Dr Frantz was a forestry engineer looking into ways of cutting thicker trees faster. His early experiments with ultra-highpressure (UHP) Water jets (Jets with a pressure of over Thirty Thousand psi) in the 1950s and 60s proved quite successful. His technique however, relying as it did on dropping huge weights onto columns of water and forcing it through tiny orifices, had unreliable effects (often creating pressures higher than those used in industry today) and often led to parts becoming worn after mere days of use.
It seems ironic that Dr. Frantz' concept, while hugely successful in so many fields today, is used for cutting wood hardly at all.
The science stuff
Waterjet cutting has been shown to do things that other technologies apparently cannot, from cutting details in stone, glass and metals to drilling holes in titanium and even as far as cutting foods. All this is done with practically no tooling costs.
Waterjet cutting is a cold cutting process, a supersonic waterjet stream performs a rapid erosion process, wearing away small grains of material. Abrasives can be added to the stream to increase the power of this process many times over.
At its most basic, water flows from a pump, through plumbing and out a cutting head. It is not all that simple however as the jets involved are pressurised to tens of thousands of psi.
First a pump is used to pressurise the water and provide it to the water circuit at a regulated rate. The most commonly used types of pump are direct drive pumps and intensifier pumps. Direct drive pumps, while slowly gaining acceptance in the industry, are less common as the maximum continuous operating pressure supplied by a direct pump is between twenty and fifty thousand psi while an intensifier pump can provide up to eighty thousand psi.
Once the pump has created the water pressure, the water is delivered to the cutting head via high-pressure plumbing. The plumbing usually consists of coils of quarter inch stainless steel tubing, as coiled tubing is more flexible. The water supply to the cutting head needs to have some flexibility as it is travelling to a part that may be moving through up to 5 axes.
The orifice (generally made from a gemstone, often ruby) of the cutting head focuses the jet to a fine cutting tool of less than a millimeter in diameter capable of cutting marble, stainless steel or granite up to 100 millimeters thick.
All in all a rather frightening peice of technology to be providing technical support for.
For more technical information than is present here check out
http://www.jetedge.com/heart/heart.html