DEFINITION OF ABRASIVE WATER JET An abrasive water jet is a jet of water which contains abrasive material. Usually the water exits a nozzle at a high speed and the abrasive material is injected into the jet stream. This process is sometimes known as entrainment in that the abrasive particles become part of the moving water much as passengers become part of a moving train. Hence as with a train the water jet becomes the moving mechanism for the particles. However a high speed jet of a premixture of the abrasive and the water would also be defined as an abrasive water jet. The purpose of the abrasive water jet is to perform some machining or finishing operation such as cutting, boring, turning, etc. The use of the abrasive water jet for machining or finishing purposes is based on the principle of erosion of the material upon which the jet hits. Each of the two components of the jet, i.e. the water and the abrasive material has both a separate purpose and a supportive purpose. It is the primary purpose of the abrasive material within the jet stream to provide the erosive forces. It is the primary purpose of the jet to deliver the abrasive material to the workpiece for the purpose of erosion. However the jet also accelerates the abrasive material to a speed such that the impact and change in momentum of the abrasive material can perform its function. In addition it is an additional purpose of the water to carry both the abrasive material and the eroded material clear of the work area so that additional processing can be performed. In one way or another in any machining process the spent material must be gotten out of the way and the water jet provides that mechanism.