The cutting speed and depth of the water jet increase with the decrease of the nozzle outlet diameter. However, when the nozzle diameter is reduced under a certain pressure, the jet will atomize near the nozzle due to the air entrainment, which makes it lose the cutting ability. The cutting depth and width of the workpiece decrease linearly with the decrease of nozzle diameter. Under the same pressure, reducing the nozzle diameter will reduce the energy consumption ratio of jet cutting. The straightness of the workpiece in the moving direction of the high pressure jet has nothing to do with the nozzle diameter. By observing the surface quality of the fracture surface of the machined parts with different materials and different process parameters, it is found that there are common features in the cross-section morphology of the machined parts: the upper part of the cross-section is smooth, while the lower part has concave convex oblique stripes; when the jet penetration ability is low, there is obvious concave area at the bottom of the cross-section; the shape of the cut section of the machined parts is V-shaped, with the upper part larger and the lower part smaller, When the depth of the incision reaches a certain extent, the width of the downstream section does not change. In addition, the cut angle of copper, aluminum, marble and granite is between 514 ° and 616 ° measured. The cut angle of different materials is slightly different, and the size of the cut angle has nothing to do with the nozzle diameter. The width of the cut is larger than the diameter of the jet, and the smaller the diameter is, the more obvious the trend is.

However, with the increase of nozzle diameter (from 0.1 mm to 0.4 mm), the cutting depth decreases. The outlet diameter of nozzle for cutting is recommended to be within 0.1L ~ 0.3mm. In addition, with the increase of nozzle diameter, the cutting speed and cutting depth decrease, but the width of cutting seam increases, that is, the amount of material damage per unit time increases. Under the same pressure condition, the quality of material cutting seam processed with 0.1 mm and 0.4 mm diameter nozzles is compared. It is also found that with the increase of nozzle diameter, the cutting seam becomes wider, the chip particle size becomes larger, and the quality (roughness) of cutting seam becomes worse. The influence of nozzle diameter on cutting quality. The straightness of the sample in the direction of jet movement has nothing to do with the nozzle diameter, and the size of the notch angle has nothing to do with the nozzle diameter. Under the same pressure, the decrease of nozzle diameter will reduce the penetration ability of jet, which will reduce the cutting quality. Considering many factors such as energy consumption, material saving, cutting efficiency and equipment investment, it is better to choose nozzle diameter of 016-110mm for common material cutting, and abrasive jet cutting below 012mm is not suitable. It can be considered that the total energy relationship of material crushing increases with the increase of jet power does not change. Although the jet power increases with the increase of jet pressure and nozzle diameter, the effect is quite different. The former obviously increases the cutting speed and depth, while the latter only increases the amount of material breakage, but decreases the cutting speed and depth. However, with the increase of the nozzle diameter, the contact area of the jet on the processed material increases, which increases the crushing resistance of the material, resulting in the decrease of the cutting speed and depth.

Therefore, when the jet is used in cutting operation, increasing the jet pressure is an effective way to improve the operation efficiency. However, in terms of jet cleaning, derusting and stripping operations, the cutting depth is almost not considered, and the more important factor is the jet area. Therefore, when the jet pressure meets the cleaning requirements, increasing the nozzle diameter is more effective to improve the operation speed.