# Applications of Water Jet Cutting Technology in Agricultural Engineering: A Review
## 2 Description and Components of Water Jet Cutting Technology  
The water jet cutting system consists of a water supply device, a filter device, a pressurizing device, a jet nozzle, and a working object (Figure 1). When working, pure water in the water supply device is filtered, compressed, and mixed with the jet medium in disparate methods (pre-mixing or post-mixing) to form the working fluid. Then, the working fluid is ejected from the jet nozzle and acts on the surface of the working object. Finally, the object cracks or breaks under the continuous impact of the working fluid until the cutting operation is completed [27; 28; 29; 30; 31]. Therefore, water jet cutting is a dynamic destruction process. Agricultural materials refer to the objects involved in breeding, planting, growing, and processing [32]. Cutting operations (i.e., peeling, slicing, trimming, etc.) may be done in the factory. When working in the field, mobile machines with jet cutting systems need to carry enough water with them for harvesting, fertilizing, or other purposes [25; 33].  
Water jet cutting parameters of jet pressure, nozzle diameter, traverse speed, and target distance control the cutting outcome. The jet pressure is adjusted at the pressurizing device and may increase with the quality requirements and costs of the pressurizing device [21; 25]. There are two common pumps, involving the triplex pump and the piston-type pump, which can generate pressures greater than 100 MPa [34]. The triplex pump directly pressurizes the water jet, while the piston-type pump indirectly pressurizes the water jet through pressurizing hydraulic oil or air [34]. The nozzle diameter, traverse speed, and target distance are adjusted as required at the jet nozzle. The nozzle is generally made of wear-resistant materials such as artificial gemstones, which can withstand high-speed and high-pressure jets [35].  
There are three water jet cutting technologies with different working fluids, including pure water jet cutting technology, abrasive water jet (AWJ) cutting technology, and liquid jet cutting technology [6; 9; 36]. First, the working fluid of pure water jet cutting technology is pure water, which does not need to be mixed with other media, while the  
Figure 1: Operation flow chart of water jet cutting system.  
other two technologies require a mixture of water and jet media. Second, the abrasive water jet cutting technology has a stronger cutting ability than the pure water jet cutting technology due to the addition of solid abrasives in the working fluid, involving typical hard abrasives such as garnet and fine river sand, as well as salt particles, sugar particles, and ice particles for processing food [37]. Third, liquid jet cutting technology refers to cutting materials with a working fluid that mixes a liquid medium with water, which is often used to cut vegetables for disinfection, cut soils for jet fertilization, or improve cutting ability [25; 38; 39]. There are two mixing methods, which have different mixing states of water and jet media before and after entering the nozzle. Water and jet media are mixed in a mixing device before entering the nozzle named the pre-mixing method, and they are mixed in the nozzle named the post-mixing method [25; 40]. For the post-mixing method, jet media are inhaled by the negative pressure generated by high-speed water jets entering the mixing chamber of the nozzle and then are ejected after mixing with water jets [41]. As a result, the post-mixing jet nozzle has one more mixing medium inlet (Figure 2) [25; 41].