# Recent Progress Trend on Abrasive Waterjet Cutting of Metallic Materials: A Review
## 3 Abrasive Waterjet Cutting Process Parameters and Influences
### Abrasive Waterjet Cutting Input Process Parameters Functions and Influences
#### 3.1.3 Nozzle System  
The nozzle system comprises the material type, nozzle diameter (ND), and orifice diameter (OD). The orifice ranges from 0.13 to 0.76 mm [95]. It is accountable for transforming water pressure into velocity; moreover, potential energy is converted into kinetic that is being transmitted to abrasive particles. The nozzle focuses the abrasive waterjet and leads it to the workpiece [6]. An illustration of a nozzle system working scheme is shown in Figure 5.  
As illustrated in Figure 5, the waterjet pressure water travels at a high velocity and generates a Venturi effect or vacuum in the mixing chamber located beneath the orifice. A metered portion of abrasive particles enters through the abrasive inlet and is forced down with the waterjet stream in the mixing chamber [96]. The abrasive particles are mixed with the waterjet, creating an abrasive water jet. The nozzle is a vulnerable component of an abrasive waterjet machine and is commonly composed of silicon carbide, tungsten carbide cobalt, boron carbide, composite, and ceramic materials. Varied materials possess diverse properties that enable a nozzle to lengthen its utilization and wear [96]. In comparison to metals, ceramic nozzles (SiC, Al\({}_{2}\)O\({}_{3}\), ZrO\({}_{2}\), B\({}_{4}\)C and Si\({}_{2}\)N\({}_{4}\)) are universally used in line with mechanical properties, maximum hardness, a high melting point, and lesser resistance to heat shock. Furthermore, they can work 30 times longer than other carbon steel nozzles [91].  
Impacts of nozzle and orifice diameter: Variation in the nozzle diameter and orifice leads to machining inconsistency due to the ascending airflow rate, jet deviating, and path size, hence impacting the material removal rate, surface roughness, and geometric accuracy in the broad-spectrum [6]. Furthermore, [PERSON] et al. [36] have investigated cutting austenitic steel AISI 304, which has recently been the most prevalent type of anti-corrosion material in various industrial applications. They used different abrasive nozzle diameter sizes including 0.76 mm and 1.02 mm. They conclude that the minimum surface roughness was achieved by using the smallest nozzle diameter of 0.76 mm. Additionally, [PERSON] et al. [27] have studied surface roughness in cutting Titanium Ti6 AL4V using an abrasive waterjet machine, where variations in the diameter ratio of the focusing nozzle and orifice were adopted. A different approach of ratio 3:1 nozzle and orifice diameter were employed in their experiments. The results indicate that increasing the waterjet orifice and focusing the nozzle diameter can minimize the surface roughness of the cut material. Later, [PERSON], et al. [97] has examined the nozzle head oscillating method in AWJ cutting of aluminum hybrid composites. They concluded that a lower degree level of oscillation angle decreased the Kerf taper angle and surface roughness. Substantially, these previous  
Figure 5: Nozzle system [92].  
researches indicate that the nozzle diameter and orifice influences the material removal rate, surface roughness, and geometric accuracy in a broad-spectrum.