Water Jet Cutting Overview
Dr. Norman Franz is regarded as the father of water jet cutting. 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. 
In 1979, Dr. Mohamed Hashish 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 water jet cutter. He used garnet abrasives, a material commonly used on sandpaper. With this method, the water jet cutter could cut virtually any material.
The water jet cutter is commonly connected to a high-pressure water pump where the water is ejected from the nozzle, cutting through the material by spraying it with the jet of high-speed water. Water jets can be used to cut diverse materials from prepared foods to metals because the nature of the 
cutting stream can be easily modified. There are few materials that cannot be effectively cut with a water jet cutter. Water jet cuts are not typically limited by the thickness of the material, and are capable of cutting materials over twelve inches (30 cm) thick