When the imported water jet works, it consumes a lot of sand pipe, and the cutting force of the water jet is very strong. The mold of the water jet is an L-shaped tubular object. Water will impact the wall of the L-Bend and cause the loss of the die in the process of L-Bend. Due to the existence of viscous force, the water velocity increases with the increase of the distance from the pipe wall. Therefore, although the flow velocity of the water jet is quite large, the wear of the inner wall of the water jet is not serious. Secondly, the friction of the water jet mainly comes from the sand particles inside, and the coefficient of viscosity between sand particles and water is larger, so that the sand particles are more easily driven by water, so as to achieve greater speed, and the water with greater speed is in the center of the pipe, so the sand particles will not touch the pipe wall, so the wear will be reduced

There is also a question: when the water column is ejected, does the outlet give him any force to make it eject faster, and then the force increases accordingly? The pressure at the water outlet of the water jet is above 50 MPa, which is equivalent to the pressure generated by placing 5 kilogram objects on an area of 1 square millimeter. Under the action of such a large pressure, when the supersonic water rushes to the material to be processed, due to the sudden obstruction, its speed will drop rapidly, and the pressure will increase suddenly. In an instant, it will produce a huge impact force, which will cause brittle fracture in a very small area of the processed part, so as to achieve the purpose of cutting the workpiece. If silica and other grinding materials are added into water, the cutting ability of water jet will be doubled, and the machining effect is obviously better than that of metal cutting tool. It can be used to process complex surfaces and parts cut along arbitrary curves that cannot be processed by metal tools. In the process of processing, not only the incision of the workpiece processed by the "water knife" is neat and smooth, without rough edge, delamination, tearing, deformation and other problems, but also the heat generated in the working process can be almost taken away by water. At the same time, in the process of cutting, the vibration and noise caused by the "water knife" are very small, and the generated small amount of chips will also go with the water flow, so there will be no chip flying.