Recent Advances and Status of Abrasive Jet Machining Technology

Compared with traditional machining technology, abrasive jet machining (AJM) has attracted wide attention due to its distinct advantages of negligible thermal effect, high machining flexibility and high machining versatility. In recent years, AJM has been widely used in micro-cutting, micro-flow channel preparation, surface polishing and other fields, and its development has been changed from macroscopic scale to microscopic scale, from rough machining to fine machining. From the view of the nature or origin of abrasive jet, traditional abrasive jets are mainly divided into (abrasive) water jet, abrasive slurry jet and abrasive air jet. Firstly, this paper summarized the backgrounds, principles and characteristics of each jet technology. Also, some new technologies such as multiphase jet machining and high-pressure abrasive slurry jet machining developed in recent years were reviewed. When facing the complex requirements of application, how to select the most suitable abrasive jet technology for application is difficult. Then, in order to better understand and apply these abrasive jet technologies, this paper made a deep analysis and comparison from the following aspects: jet velocity, jet pressure, jet beam diameter, erosion profile and machining mechanism. Finally, the applications in microchannel preparation and surface finishing and the existing problems were analyzed. The advantages and disadvantages between multiphase jet and low-pressure abrasive slurry jet in terms of surface polishing were also analyzed in-depth. The results show that the abrasive air jet has the advantage of using low air pressure to achieve a relatively high-speed flow, thus the material removal can be quick. For example, an air jet of 0.8 MPa can achieve an average particle velocity of 292 m/s, while abrasive water jet requires an operating pressure of at least 180 MPa to achieve this velocity. In abrasive air jet, however, the expansion of air usually causes the air-particle jet to diverge significantly after leaving the orifice, thereby enlarging the machining area, i.e., resulting in a poor resolution. A widely used method is to cover a metallic erosion resistant mask on the surface of workpiece to expose only the area processed by the abrasive air jet. At present, masked abrasive air jet can produce microchannels with widths as low as 10 μm. The jet beam diameter of abrasive slurry jet and abrasive water jet can be as low as 50 μm, and thus the microchannel can be directly etched on the target surface. In terms of fluid jet polishing, liquid-based abrasive slurry jet polishing has lower material removal rate than abrasive air jet polishing but provides better surface roughness. With an eye to combine both advantages, an attempt to build a bridge between air and water-based abrasive jet polishing systems was presented as multiphase jet. W-shape removal is more complicated for polishing path planning and would induce mid-high spatial frequency texture on the polished surface. Therefore, compared with the W-shaped erosion profile in abrasive slurry jet, the U-shaped erosion profile in multiphase jet is more beneficial to obtain a flat polished surface. This review helps to understand the subtle differences among the abrasive jets, and provides a reference for applying abrasive jet machining technology to microfabrication and surface finishing. © 2022, Chongqing Wujiu Periodicals Press. All rights reserved.