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Principles of waterjet
Waterjet technology may seem simple, but in fact it is very complex. When water is forced through a small opening and its pressure is raise to 55,000 psi, it can cut various soft material including food, paper, diaper, rubber and foam. When a small amount of abrasive such as garnet is added into the jet, the “abrasive waterjet” can cut any hard material including steel, composites, stone and glass. In addition, the power of UHP water stream can be increased for surface cleaning applications, such as ship cleaning or auto painting equipment. |
Advantages of waterjet
 Thanks to its much acclaimed power, speed and versatility, ultra-high pressure (UHP) waterjet has become the fastest-growing machining process in the world.
After applying UHP waterjet in their production, manufacturers can enjoy higher efficiency and better production capacity. Today, waterjet can cut material from food and paper to composites, steel and even rare metal quickly and accurately. |
The advantages of waterjet include:
Stronger cutting capability
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Cut virtually any material with ease and meet the requirements of all applications |
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Cold process with no heat effect or mechanical deformation |
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Cut material with thickness from 1/16in (1mm) to 8in (200mm) into any shape in just one pass |
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Pure water waterjet can quickly cut various soft material, such as rubber, cork and foam |
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It takes less than two minutes to switch from pure water mode to abrasive waterjet |
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Abrasive waterjet can cut various had material, such as metal, stone, plastic, composites and glass and produce good kerf quality |
Lower material and production costs
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Minimal requirements on fixturing and machining |
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Accurate cutting and smooth kerf ensure tight layout, reducing waste and improving profit and productivity at the same time |
Green technology and complementary process
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Minimal requirements on fixturing and machining |
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Waterjet can be used as complementary process to other cutting methods such as wire cutting, laser, milling and plasma |
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Although every shop has its unique cutting requirements, most of them will find that waterjet can improve their production capability and profit |
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No dust, poisonous gas or other gaseous impurity is produced during waterjet cutting and no hazardous material is generated | |
History of Waterjets
 Dr. Norman Franz is regarded as the father of the waterjet. He was the first person who studied the use of ultrahigh-pressure (UHP) water as a cutting tool. The term UHP is defined as more than 30,000 pounds per square inch (psi). Dr. Franz, a forestry engineer, wanted to find new ways to slice thick trees into lumber. In the 1950’s, Franz first dropped heavy weights onto columns of water, forcing that water through a tiny orifice. He obtained short bursts of very high pressures (often many times higher than are currently in use), and was able to cut wood and other materials. His later studies involved more continuous streams of water, but he found it difficult to obtain high pressures continually. Also, component life was measured in minutes, not weeks or months as it is today.
Dr. Franz never made a production lumber cutter. Ironically, today wood cutting is a very minor application for UHP technology. But Franz proved that a focused beam of water at very high velocity had enormous cutting power — a power that could be utilized in applications beyond Dr. Franz’s wildest dreams.
In 1979, Dr. Mohamed Hashish working at Flow Research, began researching methods to increase the cutting power of the waterjet so it could cut metals, and other hard materials. Dr. Hashish, regarded as the father of the abrasive-waterjet, invented the process of adding abrasives to the plain waterjet. He used garnet abrasives, a material commonly used on sandpaper. With this method, the waterjet (containing abrasives) could cut virtually any material. In 1980, abrasive-waterjets were used for the first time to cut steel, glass, and concrete. In 1983, the world’s first commercial abrasive waterjet cutting system was sold for cutting automotive glass. The first adopters of the technology were primarily in the aviation and space industries which found the waterjet a perfect tool for cutting high strength materials such as Inconel, stainless steel, and titanium as well as high strength light-weight composites such as carbon fiber composites used on military aircraft and now used on commercial airplanes. Since then, abrasive waterjets have been introduced into many other industries such as job-shop, stone, tile, glass, jet engine, construction, nuclear, and shipyard, to name a few.
The basic technology is both simple and extremely complex. At its most basic, water flows from a pump, through plumbing and out a cutting head. It is simple to explain, operate and maintain. The process, however, incorporates extremely complex materials technology and design. To generate and control water at pressures of 60,000 psi requires science and technology not taught in universities. At these pressures a slight leak can cause permanent erosion damage to components if not properly designed. Thankfully, the waterjet manufacturers take care of the complex materials technology and cutting-edge engineering. The user need only be knowledgeable in the basic waterjet operation.
Essentially, there are two types of waterjets; (1) pure waterjet and (2) abrasive waterjet. Machines are designed to employ only waterjet, only abrasive waterjet, or both. With any type, the water must first be pressurized. |
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