History of the Waterjet 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 late 1950's and early 1960’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. How High-Pressure Water is Created 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. The Pump The pump is the heart of the waterjet system. The pump pressurizes the water and delivers it continuously so that a cutting head can then turn that pressurized water into a supersonic waterjet stream. Teston Machine Corporation uses an intensifier based pump. Intensifier based pumps Two fluid circuits exist in a typical intensifier pump, the water circuit and the hydraulic circuit. The water circuit consists of the inlet water filters, booster pump, intensifier, and shock attenuator. Ordinary tap water is filtered by the inlet water filtration system – usually comprising of a 1 and a 0.45 micron cartridge filter. The filtered water then travels to the booster pump, where the inlet water pressure is maintained at approximately 90 psi – ensuring the intensifier is never “starved for water.” The filtered water is then sent to the intensifier pump and pressurized to up to 60,000 psi. Before the water leaves the pump unit to travel through the plumbing to the cutting head, it first passes through the shock attenuator. This large vessel dampens the pressure fluctuations to ensure the water exiting the cutting head is steady and consistent. Without the attenuator, the water stream would visibly and audibly pulse, leaving marks on the material being cut. The hydraulic circuit consists of an electric motor (25 to 200 HP), hydraulic pump, oil reservoir, manifold, and piston biscuit/plunger. The electric motor powers the hydraulic pump. The hydraulic pump pulls oil from the reservoir and pressurizes it to 3,000 psi. This pressurized oil is sent to the manifold where manifold’s valves create the stroking action of the intensifier by sending hydraulic oil to one side of the biscuit/plunger assembly or the other. The intensifier is a reciprocating pump, in that the biscuit/plunger assembly reciprocates back and forth, delivering high-pressure water out one side of the intensifier while low-pressure water fills the other side. The hydraulic oil is then cooled during the return back to the reservoir. The advanced technology in the pump is found in the intensifier. As mentioned briefly in the description of the water circuit, the intensifier pressurizes the filtered tap water to up to 60,000 psi. Intensifier pumps utilize the “intensification principle.” Hydraulic oil is pressurized to a pressure of 3,000 psi. The oil pushes against a piston biscuit. A plunger with a face area of 20 times less than the biscuit pushes against the water. Therefore, the 3,000-psi oil pressure is “intensified” twenty times, yielding 60,000-psi water pressure. The “intensification principle” varies the area component of the pressure equation to intensify, or increase, the pressure.  Pressure = Force /Area If Force = 20, Area = 20, then Pressure = 1. If we hold the Force constant and greatly reduce the Area, the Pressure will go UP. For example, reduce the Area from 20 down to 1, the Pressure now goes up from 1 to 20.  The intensification ratio, therefore, is 20:1.  In waterjet cutting, the material removal process can be described as a supersonic erosion process. It is not pressure, but stream velocity that tears away microscopic pieces or grains of material. Pressure and velocity are two distinct forms of energy. But how is the pump’s water pressure converted to this other form of energy, water velocity? The answer lies in a tiny jewel. A jewel is affixed to the end of the plumbing tubing. The jewel has a tiny hole in it. The pressurized water passes through this tiny opening changing the pressure to velocity. At approximately 40,000 psi the resulting stream that passes out of the orifice is traveling at Mach 2. And at 60,000 psi the speed is over Mach 3. If you have any further questions please contact us .