Waterjet Power

A water jet cutter, also known as a waterjet, is a tool capable of slicing into metal or other materials  using a jet of water at high velocity and pressure, or a mixture of water and an abrasive substance.

The process is essentially the same as water erosion found in nature but greatly accelerated and concentrated. It is often used during fabrication or manufacture of parts for machinery and other devices. It is the preferred method when the materials being cut are sensitive to the high temperatures generated by other methods. It has found applications in a diverse number of industries from mining to aerospace where it is used for operations such as cutting, shaping, carving, and reaming.

The picture on the left clearly illustrates the components of a waterjet cutting head:

1) High Pressure Water Inlet
2) Jewel (ruby or Diamond)
3) Abrasive (Garnet)
4) Mixing Tube
5) Guard
6) Cutting Water Jet
7) Cut Material

History
In the 1950s, forestry engineer Norman Franz experimented with an early form of water jet cutter to cut lumber. The technology did not advance notably until the 1970-80s when Mohamed Hashish added abrasives to the water. This allowed Yih-Ho Michael Pao to develop commercial “ultrahigh-pressure water-jets and abrasive-waterjets into better tools for industrial cutting, drilling, and milling, for the flexible factory automation.

Today the water jet is unparalleled in many aspects of cutting and has changed the way many products are manufactured. Many types of water jets exist today, including pure water jets(water only), abrasive water jets, percussive water jets, cavitation jets and hybrid jets.

Operation
The cutter is commonly connected to a high-pressure water pump where the water is then ejected from the nozzle, cutting through the material by spraying it with the jet of high-speed water. Additives in the form of suspended grit or other abrasives, such as garnet and aluminum oxide, can assist in this process.

Benefits
An important benefit of the water jet cutter is the ability to cut material without interfering with the material’s inherent structure as there is no “heat-affected zone” or HAZ. Minimizing the effects of heat allows metals to be cut without harming or changing intrinsic properties.

Water jet cutters are also capable of producing rather intricate cuts in material. With specialized software and 3-D machining heads, complex 3-D shapes can be produced.

The kerf, or width, of the cut can be changed by changing parts in the nozzle, as well as the type and size of abrasive. Typical abrasive cuts are made with a kerf in the range of 0.04″ to 0.05″ (1.016 to 1.27 mm), but can be as narrow as 0.02″ (0.508 mm). Non-abrasive cuts are normally 0.007″ to 0.013″ (0.178 to 0.33 mm), but can be as small as 0.003″ (0.076 mm), which is approximately the width of a human hair. These small jets can make very small detail possible in a wide range of applications.

Waterjets are capable of attaining accuracy of 0.005″ (0.13 mm), and repeatability of 0.001″ (0.025 mm).

Enviromentally Friendly
Water jet is considered a “green” technology. Water jets produce no hazardous waste, reducing waste disposal costs. They can cut off large pieces of reusable scrap material that might have been lost using traditional cutting methods. Parts can be closely nested to maximize material use, and the water jet saves material by creating very little kerf.

Water jets use very little water (a half gallon to approximately one gallon per minute depending on cutting head orifice size), and the water that is used can be recycled using a closed-looped system. Waste water usually is clean enough to filter and dispose of down a drain.

The garnet abrasive is a non-toxic natural substance that can be recycled for repeated use. Garnet usually can be disposed of in a landfill. Water jets also eliminate airborne dust particles, smoke, fumes, and contaminants from cutting materials such as asbestos and fiberglass. This greatly improves the work environment and reduces problems arising from operator exposure.


 

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