Water jet cutter
Overview
 
A water jet cutter, also known as a waterjet, is a tool capable of slicing into metal
Metal
A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...

 or other materials (such as granite
Granite
Granite is a common and widely occurring type of intrusive, felsic, igneous rock. Granite usually has a medium- to coarse-grained texture. Occasionally some individual crystals are larger than the groundmass, in which case the texture is known as porphyritic. A granitic rock with a porphyritic...

) using a jet of water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...

 at high velocity and pressure, or a mixture of water and an abrasive
Abrasive
An abrasive is a material, often a mineral, that is used to shape or finish a workpiece through rubbing which leads to part of the workpiece being worn away...

 substance. The process is essentially the same as water erosion
Erosion
Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...

 found in nature but greatly accelerated and concentrated. It is often used during fabrication or manufacture of parts for machinery and other devices.
Encyclopedia
A water jet cutter, also known as a waterjet, is a tool capable of slicing into metal
Metal
A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...

 or other materials (such as granite
Granite
Granite is a common and widely occurring type of intrusive, felsic, igneous rock. Granite usually has a medium- to coarse-grained texture. Occasionally some individual crystals are larger than the groundmass, in which case the texture is known as porphyritic. A granitic rock with a porphyritic...

) using a jet of water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...

 at high velocity and pressure, or a mixture of water and an abrasive
Abrasive
An abrasive is a material, often a mineral, that is used to shape or finish a workpiece through rubbing which leads to part of the workpiece being worn away...

 substance. The process is essentially the same as water erosion
Erosion
Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...

 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
Mining
Mining is the extraction of valuable minerals or other geological materials from the earth, from an ore body, vein or seam. The term also includes the removal of soil. Materials recovered by mining include base metals, precious metals, iron, uranium, coal, diamonds, limestone, oil shale, rock...

 to aerospace
Aerospace
Aerospace comprises the atmosphere of Earth and surrounding space. Typically the term is used to refer to the industry that researches, designs, manufactures, operates, and maintains vehicles moving through air and space...

 where it is used for operations such as cutting, shaping, carving, and reaming
Reamer
A reamer is a metalworking tool used to create an accurate sized hole. The process is called reaming. They may be used as a hand tool or in a machine tool, such as a milling machine or drill press.-Construction:...

.

History

In the 1950s, forestry engineer Norman Franz experimented with an early form of water jet cutter to cut lumber. However, the technology did not advance notably until the 1970-80s when Mohamed Hashish
Mohamed Hashish
Mohamed Hashish is an Egyptian-born research scientist best known as the father of the abrasive water jet cutter.- Youth and Schooling :...

 added abrasives to the water. This and other concepts allowed Yih-Ho Michael Pao
Yih-Ho Michael Pao
Yih-Ho Michael Pao is an American entrepreneur and hydro-engineer. He was an early pioneer in developing large-scale wind turbines. In 2000, Dr. Pao was elected a member of the National Academy of Engineering for his research, development, and commercialization of ultrahigh-pressure waterjet...

 to develop commercial "ultrahigh-pressure water-jets and abrasive-waterjets into better tools for industrial cutting, drilling, and milling, especially 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
Cavitation
Cavitation is the formation and then immediate implosion of cavities in a liquidi.e. small liquid-free zones that are the consequence of forces acting upon the liquid...

 jets and hybrid jets.

Operation

The cutter is commonly connected to a high-pressure
Pressure
Pressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...

 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
Garnet
The garnet group includes a group of minerals that have been used since the Bronze Age as gemstones and abrasives. The name "garnet" may come from either the Middle English word gernet meaning 'dark red', or the Latin granatus , possibly a reference to the Punica granatum , a plant with red seeds...

 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).

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.

Meatcutting using waterjet technology eliminates the risk of cross contamination
Cross Contamination
Cross Contamination is an album by the rock bands Batmobile and Peter Pan Speedrock. It was released in 2008 by Suburban Records.-Track listing:#"Hellalujah"#"Go Satan Go"#"Killerspeed"#"Big Toy"#"Straight Back To Hormoneville"#"Transsylvanian Express"...

 since there is no contact medium (namely, a blade) between different animals in the abattoir.

Versatility

Because the nature of the cutting stream can be easily modified the water jet can be used in nearly every industry; there are many different materials that the water jet can cut. Some of them have unique characteristics that require special attention when cutting.

Materials commonly cut with a water jet include rubber, foam, plastics, leather, composites, stone, tile, metals, food, paper and much more. Materials that cannot be cut with a water jet are tempered glass, diamonds and certain ceramics.

Water jet cuts are not typically limited by the thickness of the material, and are capable of cutting materials over eighteen inches (45 cm) thick. The penetrating power of these tools has led to the exploration of their use as anti-tank weapons but, due to their short range and the advent of composite armour
Composite armour
Composite armour is a type of vehicle armour consisting of layers of different material such as metals, plastics, ceramics or air. Most composite armour are lighter than their all-metal equivalent, but instead occupy a larger volume for the same resistance to penetration...

, research was discontinued.

Availability

Commercial water jet cutting systems are available from manufacturers all over the world, in a range of sizes, and with water pumps capable of a range of pressures. Typical water jet cutting machines have a working envelope as small as a few square feet, or up to hundreds of square feet. Ultra-high pressure water pumps are available from as low as 40,000 psi (276 MPa) up to 100,000 psi (689 MPa).

Process

There are six main process characteristics to water jet cutting:
  1. Uses a high velocity stream of abrasive particles suspended in a stream of Ultra High Pressure Water (30,000 - 90,000 psi) which is produced by a water jet intensifier pump.
  2. Is used for machining a large array of materials, including heat-sensitive, delicate or very hard materials.
  3. Produces no heat damage to workpiece surface or edges.
  4. Nozzles are typically made of sintered boride
    Boride
    In chemistry a boride is a chemical compound between boron and a less electronegative element, for example silicon boride . The borides are a very large group of compounds that are generally high melting and are not ionic in nature. Some borides exhibit very useful physical properties. The term...

    .
  5. Produces a taper of less than 1 degree on most cuts, which can be reduced or eliminated entirely by slowing down the cut process.
  6. Distance of nozzle from workpiece affects the size of the kerf and the removal rate of material. Typical distance is .125" (3.175mm).


Temperature is not as much of a factor.

Edge Quality

Edge quality for water jet cut parts is defined with the numbers 1 through 5. Lower numbers indicate rougher edge finish; higher numbers are smoother. For thin materials, the difference in cutting speed for quality 1 could be as much as 3 times faster than the speed for quality 5. For thicker materials, quality 1 could be 6 times faster than quality 5. For example, 4” thick aluminum Q5 would be 0.72 ipm (18 mm/min) and Q1 would be 4.2 ipm (107 mm/min), 5.8 times faster.

Multi-axis cutting

With recent advances in control and motion technology, 5-axis water jet cutting (abrasive and pure) has become a reality. Where the normal axes on a water jet are named X (back/forth), Y(left/right) and Z (up/down), a 5-axis system will typically add an A axis (angle from perpendicular) and C axes (rotation around the Z-axis). Depending on the cutting head, the maximum cutting angle for the A axis can be anywhere from 55, 60, or in some cases even 90 degrees from vertical. As such, 5-axis cutting opens up a wide range of applications that can be machined on a water jet cutting machine.

A 5-axis cutting head can be used to cut 4-axis parts, where the bottom surface geometries are shifted a certain amount to produce the appropriate angle and the Z-axis remains at one height. This can be useful for applications like weld preparation where a bevel angle needs to be cut on all sides of a part that will later be welded, or for taper compensation purposes where the kerf angle is transferred to the waste material - thus eliminating the taper commonly found on water jet-cut parts. A 5-axis head can cut parts where the Z-axis is also moving along with all the other axis. This full 5-axis cutting could be used for cutting contours on various surfaces of formed parts.

Because of the angles that can be cut, part programs may need to have additional cuts to free the part from the sheet. Attempting to slide a complex part at a severe angle from a plate can be difficult without appropriate relief cuts.

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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