# Recent Progress Trend on Abrasive Waterjet Cutting of Metallic Materials: A Review
## 1 Introduction
### AWJM Process and Advantages  
The cutting process is a core method in the manufacturing industry. AWJM is highly capable of machining from hard to soft materials at a very low machining force, which avoids the destruction of the target workpiece's properties [3]. Abrasive waterjet machining is a non-conventional cold processing technology used for material processing with significant advantages [1; 15], which has been the reasoning behind the rapidly progressing application of AWJM, particularly in metallic materials [6]. The reduction of temperature is carried through the presence of cooling water due to the presence of cooling water, which renders AWJM [6].  
Table 1 illustrates AWJM's superiority compared to other non-conventional machines based on experimental studies on various workpieces [8; 9; 10; 16; 17; 18; 19; 20; 21]. It substantiates AWJM compared to other technologies, indicating versatility in cutting diverse material with a wide range of thickness, absence of tool wear and flexibility in cutting intricate geometries. Other machines such as EDM and ECDM involve the use of high-intensity energy to cut hard metals and materials that are difficult to machine [8; 9; 10]. However, the usage of high thermal heating sources causes craters, cracks, thermal damages, and destructively tensile residual stresses; hence, materials that are low conductors of heat are very applicable [10]. In AWJM applications, the absence of thermal distortion is achieved due to its cold cutting process since the material temperature will not exceed 70 \({}^{\circ}\)C [22]. EDM and ECDM generate hazardous solid, liquid, and gaseous products resulting in sludge containing metal ions, acids, nitrate, oils and even traces of heavy metal ions due to anodic electrochemical dissolution, which are very harmful to humans and the environment [17]. AWJM is also considered environmentally friendly and sustainable as it does not omit any hazardous vapor; hence, AWJM generates waste such as abrasives that adversely affect the environment. Sustainable manufacturing aims to achieve an efficient operation at the same time, reducing the environmental effect [17]. Recycling and reusing these abrasives make AWJM more economical, effective, and environmentally friendly [22; 23; 24]. The discussed competitive advantages of AWJM have been the rational reason behind its expanding utilization and continuous progression.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Cutting Activity** & **AWJM** & **LBM** & **EDM** & **ECDM** \\ \hline Heated affected & & & & \\ zone (HAZ) & No & Yes & Yes & Yes \\ Material Distortion & No & Yes & No & Yes \\ Tool Wear & No & No & Yes & Yes \\ Material Removal & Medium-slow & Fast (approx. 2-3) for & & \\ Rate (mm\({}^{3}\)/s) & (approx. \(\leq\) 2) & non-reflective & Medium (approx.1–2) & Medium (approx.1–2) \\  & metals, composites, & metals, composites, & & \\ Type of material & natural, electrically, & natural, electrically, & Only electrically & \\  & non-conductive, & non-conductive, & & \\  & non-reflective & non-reflective surface & metals and composites & \\ Material thickness & (mm) & Ranging \(\leq\) 304.8 & Ranging \(\leq\) 20 & Ranging \(\leq\) 304.8 & Ranging \(\leq\) 304.8 \\ Type of shapes & Complex and & Complex and & & \\  & complicated shapes & complicated shapes & Simple & Simple \\ Burr formation & Minimal & High & High & Minimal \\ Hazardous vapour & None & fumes, gases & CO \& CH\({}_{4}\) & NaOH/NaNO\({}_{3}\) \\ \hline \hline \end{tabular}
\end{table}
Table 1: Comparison of non-conventional cutting technologies [8; 9; 10; 16; 17; 18; 19; 20; 21].