# Applications of Water Jet Cutting Technology in Agricultural Engineering: A Review
## 3 Applications of Water Jet Cutting Technology on Different Agricultural Materials
### Woods  
With the increasing demand of wood and wood-based products, it is necessary to improve the utilization rate of raw materials during processing [66]. Compared with planing and sawing, water jet cutting makes smaller kerf widths, fewer dusts, and acceptable noise outputs [66]. Generally, the surface roughness and kerf width are crucial factors determining the quality of wood products [67; 68; 69].  
[PERSON] [69] conducted AWJ cutting on sixteen Korean domestic wood species and found that with the increase in the cutting depth, the surface roughness increased, and the cut width decreased. [PERSON] et al. [66] took nine important Hungarian tree species with a thickness of 25 mm as samples to study the influence of AWJ cutting technology on the moisture uptake, surface roughness, and kerf width of solid wood. The results showed that residual moisture caused by abrasive water jets mainly concentrated in the surface layer, and there were no significant changes after one day compared to the original state, so residual moisture could not affect practical applications. The mean roughness depth parameter (\(Rz\)) values varied between 15 and 85 \(\upmu\)m depending on the species and cutting direction, and they were always lower than those of planing and sawing. The entry kerf width values of various species ranged from 0.8 to 1.6 mm, and the egress width values ranged from 0.4 to 0.8 mm, which meant that the edge was not perpendicular to the material surface. This problem could be solved by properly adjusting the jet angle [67]. [PERSON] et al. [70] used garnet sand as the abrasive to cut red oak and bamboo samples. The study found that the factors affecting the surface roughness were ranked as follows: cutting pressure > traverse speed > abrasive flow rate > target distance > air-dry density. The processing quality of both woods was best when the cutting pressure was 310 MPa, the traverse speed was 0.25 m/s, the abrasive flow rate was 35 kg/h, the target distance was 3 mm, and the air-dry density was 620 kg/m\({}^{3}\). [PERSON] et al. [71] cut pine, beech, and oak samples in an abrasive water jet system (Figure 5) and determined surface roughness values by a surface test device. The tests found that surface roughness values of pine and oak samples were higher during tangential cutting and a lower cutting pressure, while beech was the opposite. The textural structure of beech specimens might have an influence on the results. The surface roughness of all samples increased with the increasing traverse speed (50-200 mm/min) and the thickness (18-54 mm) of the wood sample and decreased with the increase in the abrasive flow rate (12-27 kg/h).  
Thus, water jet cutting technology has an environmentally friendly characteristic and can be used to cut many wood species. Due to the hard material of woods, abrasives are usually used for improving cutting ability. The surface roughness of cuts is positively correlated with the cutting depth and traverse speed, and negatively correlated with the abrasive flow. Furthermore, the jet pressure, wood species, and cutting direction affect the roughness values to varying degrees. The residual moisture has a weak effect on the practical application of woods. To keep the edge of the cut perpendicular to the material surface, the jet angle should be properly adjusted.