A water jet cutter , also known as water jet or waterjet , is an industrial tool capable of cutting a wide variety of materials using highly pressurized water jets, or a mixture of water and abrasive substances. The term abrasive jet specifically refers to the use of aqueous and abrasive mixtures for cutting hard materials such as metal or granite, whereas the provisions of pure waterjet and water - Just cut refers to waterjet cutting without the use of additional abrasives, often used for softer materials such as wood or rubber.
Waterjet cuts are often used during the fabrication of machine parts. This is the preferred method when the cut material is sensitive to high temperatures generated by other methods. Waterjet cutting is used in various industries, including mining and aerospace, for cutting, shaping, and reaming.
Video Water jet cutter
History
Waterjet
When using high pressure water for erosion back as far back as the mid-1800s with hydraulic mining, it was not until the 1930s that a narrow emission of water began to emerge as an industrial cutting tool. In 1933, Paper Patents Company in Wisconsin developed a measuring, cutting, and grinding machine that used a diagonal moving waterjet nozzle to cut horizontally moving sheet of paper. This initial application is at a low pressure and limited to soft materials such as paper.
Waterjet technology developed in the postwar era when researchers around the world searched for new methods of efficient cutting systems. In 1956, Carl Johnson of Durox International in Luxembourg developed a method for cutting plastic shapes using a thin flow high-pressure waterjet, but such materials, such as paper, were soft materials. In 1958, Billie Schwacha of North American Aviation developed a system that uses ultra-high pressure liquids to cut hard material. The system uses 100,000 psi pumps (690 MPa) to provide hypersonic fluid jets that can cut high strength alloys such as PH15-7-MO stainless steel. Used as a honeycomb laminate on Mach 3 North American XB-70 Valkyrie, this method of cutting delaminates at high speed, requiring changes to the manufacturing process.
Although not effective for the XB-70 project, the concept is valid and further research continues to develop waterjet cuts. In 1962, Philip Rice of Union Carbide explored using waterjet pulsing up to 50,000 psi (340 MPa) to cut metal, stone, and other materials. Research by S.J. Leach and GL Walker in the mid-1960s expanded on traditional coal-cutting waterjet to determine the ideal nozzle shape for high-pressure waterjet cutting stones, and Norman Franz in the late 1960s focused on cutting soft waterjet material by dissolving long chain polymers in water to improve cohesive jet stream. In the early 1970s, the desire to increase the resistance of the waterjet nozzle caused Ray Chadwick, Michael Kurko and Joseph Corriveau of Bendix Corporation to come up with the idea of ​​using corundum crystals to form orifice waterjet, while Norman Franz expanded this and created a waterjet nozzle with a hole as small 0.002 inches (0.051 mm) operating at pressures of up to 70,000 psi (480 MPa). John Olsen, along with George Hurlburt and Louis Kapcsandy in the Research Flow (later the Industrial Flow), further enhanced the commercial waterjet's potential by demonstrating that treating water beforehand could improve the operational life of the nozzle.
High pressure
High-pressure vessels and pumps become affordable and reliable with the emergence of steam power. In the mid-1800s, steam locomotives were commonly used and the first efficient steam-fired firefighters operated. At the turn of the century, high-pressure reliability increased, with locomotive research leading to a six-fold increase in boiler pressure, some reaching 1,600 psi (11 MPa). Most high-pressure pumps currently operated around 500-800 psi (3.4-5.5 MPa).
High-pressure systems are increasingly shaped by aviation, automotive, and oil industries. Aircraft manufacturers such as Boeing developed seals for hydraulically reinforced control systems in the 1940s, while automotive designers followed similar research for hydraulic suspension systems. Higher pressures in hydraulic systems in the oil industry also led to the development of advanced seals and packing to prevent leakage.
The progress of this seal technology, coupled with the increase in plastic in the postwar years, leads to the development of the first reliable high pressure pump. Marlex's discovery by Robert Banks and John Paul Hogan of the Phillips Petroleum company requires a catalyst to be injected into polyethylene. The McCartney Manufacturing Company in Baxter Springs, Kansas, began producing this high-pressure pump in 1960 for the polyethylene industry. The Industrial Flow in Kent, Washington set the foundation for the commercial viability of airjets with John John's development of a high-pressure fluidier intensifier in 1973, a more refined design in 1976. Industrial Flow then combined the high pressure pump research with their waterjet nozzle research and brought waterjet cuts into the manufacturing world.
Waterjet abrasive
While cutting with water is possible for soft materials, the addition of abrasive turns the waterjet into a modern machine tool for all materials. It began in 1935 when the idea of ​​adding abrasives to the water stream was developed by Elmo Smith for abrasive liquid abrasions. Smith's design was further enhanced by Leslie Tirrell of Hydroblast Corporation in 1937, producing a nozzle design that created a mixture of high-pressure and abrasive water for the purpose of wet blasting.
The first publication on the cutting of modern Abrasive Waterjets (AWJ) was published by Dr. Mohamed Hashish in the 1982 BHR process which shows, for the first time, that waterjets with relatively small amounts of abrasives are capable of cutting hard materials such as steel and concrete.. The March 1984 issue of the Mechanical Engineering magazine shows further details and materials that were cut with AWJ such as titanium, aluminum, glass, and stone. Dr. Mohamed Hashish, was awarded a patent in forming AWJ in 1987. Hashish, which also coined the new term Waterjet Abrasive (AWJ), and his team continues to develop and improve AWJ technology and hardware for many applications now in more than 50 industries worldwide. The most important development is creating a durable mixing tube that can withstand AWJ's high pressure force, and it's Boride Products (now Kennametal) development of their ROCTEC line of tungsten ceramic composite tungsten carbide tubes that significantly improves the operational life of the AWJ Nozzle. The current work on the AWJ nozzle is on a micro abrasive waterjet so that the cut with jets smaller than 0.015 inch (0.38 mm) in diameter can be commercialized.
Working with Ingersoll-Rand Waterjet Systems, Michael Dixon implements the first production of a practical means of cutting titanium sheets - abrasive waterjet systems are very similar to those widely used today. In January 1985, the system was run 24 hours a day producing titanium components for B-1B mostly at Rocker's North American Aviation facility in Newark, Ohio.
Waterjet control
When waterjet cuts move to traditional manufacturing shops, controlling the cutters reliably and accurately is essential. Early waterjet cutting systems adapted traditional systems such as mechanical pantographs and CNC systems based on NC Parsne 1952 milling machines and running G-code. The inherent challenge to waterjet technology reveals the traditional G-Code deficiencies, as accuracy depends on varying the nozzle speed as it approaches angles and details. Creating a motion control system to incorporate these variables into major innovations to lead waterjet manufacturers in the early 1990s, with Dr. John Olsen of OMAX Corporation developing systems to precisely position the waterjet nozzle while accurately determining the speed at every point along the path, and also make use of public PC as a controller. The largest waterjet manufacturer, Flow International (spinoff of Flow Industries), recognizes the benefits of the system and licenses the OMAX software, with the result that most waterjet cutting machines worldwide are easy to use, fast and accurate.
Maps Water jet cutter
Operation
All waterjets follow the same principle by using high-pressure water that is focused into the rays by the nozzle. Most engines achieve this by first running water through a high pressure pump. There are two types of pumps used to make this high pressure; intensifier pump and direct drive or crankshaft pump. The direct drive pump works like a car engine, forcing water through a high pressure pipe using a plunger attached to the crankshaft. The intensifier pump creates pressure by using hydraulic oil to drive the piston that forces water through a small hole. The water then runs along the high pressure tube into the waterjet nozzle. In the nozzle, the water is focused into a thin ray by a gem hole. This water jet is removed from the nozzle, cutting the material by spraying it with a high-speed water jet. The process is the same for abrasive waterjets until the water reaches the nozzle. Here abrasives such as garnet and aluminum oxide, are inserted into the nozzle through an abrasive inlet. The abrasive material then mixes with water in the mixing tube and is forced out of the tip at high pressure.
Benefits
An important benefit of water jets is the ability to cut material without disturbing its inherent structure, since there is no heat affected zone (HAZ). Minimizing heat effects allows metal to be cut without damage or alter intrinsic properties. Sharp angles, bevels, piercings, and shapes with the fingers in at least all are possible.
Water jet cutters are also capable of producing complicated pieces of material. With special software and 3-D machining heads, complex shapes can be produced.
Scratches, or widths, pieces can be adjusted by swapping parts in the nozzle, as well as changing abrasive types and sizes. Typical abrasive cuts have scratches in the range of 0.04 to 0.05 at (1.0-1.3 mm), but can be as narrow as 0.02 inches (0.51 mm). Non-abrasive pieces are usually 0.007 to 0.013 in (0.18-0.33 mm), but can be as small as 0.003 inches (0.076 mm), which is approximately the size of a human hair. This small jet can allow small details in various applications.
The water jet is capable of achieving an accuracy of up to 0.005 inches (0.13 mm) and repeatability to 0.001 inches (0.025 mm).
Because of its relatively narrow scratches, water jet cutting reduces the amount of waste material produced, allowing the non-cut nesting parts to be denser than the traditional cutting method. Water jets use about 0.5 to 1 gal US (1.9-3.8 liters) per minute (depending on the size of the cutting headhole), and water can be recycled using a closed-loop system. Wastewater is usually clean enough to be filtered and discharged into the drain. Abrasive garnets are non-toxic materials that are largely recyclable for repeated use; if not, can usually be dumped in landfills. Water jets also produce less airborne dust particles, smoke, smoke, and contaminants, reducing operator exposure to hazardous materials.
Cutting meat using waterjet technology eliminates the risk of cross contamination because there is no contact medium (ie, a knife).
Versatility
Because the nature of the cutting flow can be easily modified water jet can be used in almost every industry; there are many different materials that can be cut by water jet. Some of them have unique characteristics that require special attention when cutting.
Materials commonly cut with water jets include textiles, rubber, foams, plastics, leather, composites, stones, tiles, glass, metal, food, paper and more. "Most ceramics can also be cut on abrasive jet water as the material is softer than the abrasive used (between 7.5 and 8.5 on Mohs scale)". Examples of materials that can not be cut with water jets are tempered glass and diamonds. Water jets are capable of cutting up to metal (150 mm) and 18 in (460 mm) of most materials, although in special coal mining applications, water jets are capable of cutting up to 100 ft (30 m) using an inner nozzle (25 mm).
Availability
Commercial water jet cutting systems are available from manufacturers worldwide, in various sizes, and with water pumps capable of various pressures. A typical water jet cutter has a work envelope as small as a few square feet, or up to hundreds of square feet. Ultra high pressure water pumps are available from 40,000 psi (280 MPa) to 100,000 psi (690 MPa).
Process
There are six main process characteristics for cutting water jets:
- Use high-speed flow from Ultra High Pressure Water 30,000-90.000 psi (210-620 MPa) produced by high pressure pumps with abrasive particles that may be suspended in the flow.
- Used to map a wide range of materials, including heat sensitive materials, fine or very hard materials.
- Does not produce heat damage to the workpiece surface or the edges.
- Nozzles are usually made of sinter borides or composite tungsten carbides.
- Produces a taper of less than 1 degree on most pieces, which can be reduced or eliminated entirely by slowing the cutting process or tilting the jet.
- The nozzle distance from the workpiece affects the scratch size and material release rate. The distance is usually 0.125 in (3.2 mm).
Temperature is not as big as a factor.
Edge Quality
The edge quality for the water jet piece is defined by Q1 to Q5 quality figures. A lower number indicates a rougher edge sharpness; the higher the number more smoothly. For thinner materials, the difference in cutting speed for Q1 can be as much as 3 times faster than the speed for Q5. For thicker materials, Q1 can be 6 times faster than Q5. For example, 4 inches (100 mm) thick aluminum Q5 would be 0.72 in/min (18 mm/min) and Q1 would be 4.2 in/min (110 mm/min), 5.8 times faster.
Multi-axis cutting
In 1987, Ingersoll-Rand Waterjet Systems offered a pure 5-axis waterjet cutting system called the Robotic Waterjet System. This system is an overhead gantry design, similar in overall size to the HS-1000.
With the latest advancements in control and motion technology, 5-axle and abrasive jet water cuts have become a reality. Where the normal axis on the water jet is named Y (back/forth), X (left/right) and Z (up/down), the 5-axis system will usually add the A axis (angle of perpendicular) and C axis (Rotation around Z-axis). Depending on the cutting head, the maximum cutting angle for A's axis can be anywhere from 55, 60, or in some cases even 90 degrees from vertical. Thus, cutting 5 axes opens up various applications that can be worked on a water jet cutter.
The 5-axis cutting head can be used to cut 4-axis parts, where the geometry of the lower surface is shifted to a certain amount to produce the right angle and the Z-axis remains at one altitude. This can be useful for applications such as weld preparation where the sloping angle should be cut on all sides of the later section to be welded, or for the purpose of taper compensation in which the garage angle is transferred to the waste material - thereby eliminating the taper generally found in the water jet section. The 5-axis head can cut the part where the Z-axis also moves along with all other axes. This full 5-axis cut can be used to cut the contours on the various surfaces of the formed part.
Due to the cutable angle, the program section may need to have additional pieces to free part of the sheet. Trying to shift the intricate part at a severe angle of the plate can be difficult without proper aid cuts.
See also
- CryoJet
- Laser Cutting
- Plasma cutting
- Electrical discharge machining
References
- Momber, A.W., Kovacevic, R.: The Principle of Abrasive Water Screw Machine, Springer, London, 1998.
External links
- How it Works Air Jet, HowStuffWorks.com video
- Cutting Fabrics with Jet Cutting Machines
- Waterjet Cutting - How it Works, Looking into physics reaches high water pressure to cut waterjet.
http:/nimawaterjet.com
Source of the article : Wikipedia
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