# Recent Progress Trend on Abrasive Waterjet Cutting of Metallic Materials: A Review
## 4 Abrasive Waterjet Cutting Process Parameters Improvements and Optimization
### AWJ Cutting Process Parameters Improvements  
Abrasive waterjet cutting process parameters are factors that impact the effectiveness of machining performance. Defects such as the surface quality, kerf geometric inaccuracies and low material removal rate are directly correlated to transverse speed, standoff distance, waterjet pressure, and abrasive mass flow rate as well as material properties and material thickness. Therefore, nominating suitable values for these factors should be managed appropriately. Functional relations between these responses and input parameters of AWJ cutting were obtained and studied by many experimental results of numerous authors. Table 8 details a number of experimental investigations from recently published research, providing evaluations of correlations between input and output process parameters of AWJM, particularly in cutting operations. Based on the studies summarized in Table 8, water pressure at a high level provided a higher depth of cut and higher material removal rate [33; 58]. A lower value of traverse speed ranging from 60 to 90 mm/min was favorable in achieving a lower surface roughness, and a higher material removal rate and depth of cut [30; 33; 78; 106].  
\begin{table}
\begin{tabular}{c c c c c} \hline
**Output Process** & **Analytic Equations** & **Unit of Measurement** & \begin{tabular}{c} **Equation Number** \\ **and Reference** \\ \end{tabular} \\ \hline Depth of cut (_ht_) & \(ht=L\sin 25^{\circ}\) & \
\begin{tabular}{c} \(L\) inclined length \\ of workpiece \\ _ht_ is depth of cut, \\ _vt_ is traverse speed, \\ \(W\) is kerf width \\ _(W_\(t_-W_{b}\))_ \\ _W_\(t_\) is top kerf width \\ _W_\(t_\) is bottom kerf width \\ _W_\(t_\) is bottom kerf width \\ _W_\(t_\) is thickness \\ _width_, \(h\) is thickness \\ \(l\) is sampling length, \(y\) \\ _is profile height in a \\ defined point of \(x\) -axis \\ \end{tabular} & mm & Equation (1) [103] \\ Surface roughness (R\({}_{a}\)) & \(R_{a}=\frac{1}{T}\int\limits_{0}^{l}y(x)dx\) &
\begin{tabular}{c} \(l\) is sampling length, \(y\) \\ is profile height in a \\ defined point of \(x\) -axis \\ \end{tabular} & mm\({}^{3}\)/min & Equation (2) [77] \\ \hline \end{tabular}
\end{table}
Table 7: Output process parameters analytic equation.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline \multicolumn{10}{c}{**Input Parameters**} \\ \multirow{2}{*}{Output Parameters} & \multicolumn{3}{c}{**Water Pressure, MPa**} & \multicolumn{3}{c}{**Taveser Speed, mm/min**} & \multicolumn{3}{c}{**Stand of Distance, mm**} & \multicolumn{3}{c}{**Abrasive Mass Flow Rate, g/min**} & \multicolumn{3}{c}{**Key Findings and References**} \\ \cline{2-10}  & **Model** & **Model** & **Model** & **Model** & **Model** & **Model** & **Model** & **Model** & **Model** & **Model** \\ \hline \multirow{4}{*}{DOC} & AA2  
As presented in Table 8, a value of abrasive mass flow rate ranging to 100 to 250 g/min achieved the minimum value of surface roughness and kerr taper angle [30; 106]. Thus, it has been found that a nearer standoff distance provides a better AWJ cutting performance [58; 106].