**5.1 AWJ turning**

In AWJ turning, workpiece is rotated while the jet is traversed parallel to the axis of workpiece to produce the required shape. Research efforts on AWJT were started by Hashish during 1987; since then several experimental investigations on different machining operations were made to produce near net shape parts with faster material

**Figure 10.** *Tensile specimens produced by AWJ in Mg-B4C MMC [49].*

removal rate [49]. Investigations on samples of Mg-boron carbide MMC, glass, and aluminum concluded suitability of AWJ for performing alternative machining operations.

Preliminary investigations on AWJT has revealed that AWJ turning is less sensitive to the type of material being machined unlike conventional machining, no microstructural changes were observed on AWJ machined surfaces, tensile properties of cylindrical specimens turned by AWJ remains unaffected, and relative insensitivity of AWJ to length-to-diameter ratio of work piece enables the process to turn long and small diameter components. **Figure 10** shows the tensile test Mg-B4C MMC specimens produced by AWJT. No appreciable microhardness changes were observed during turning of Mg-B4C MMC and aluminum. No ignition issues were observed during machining.

Investigations conducted by the University of Rhode Island [50, 51] have witnessed machining of screw threads on composite materials. Furthermore, it was revealed that a thread produced by AWJ has an excellent potential to provide sufficient joint strength when compared to adhesive bonded joints. Minimal structural damage on machined surfaces was observed during microstructural examinations. Still there are plenty of research opportunities which are open in AWJT field to expand the applications of AWJ in different areas. Detailed studies on AWJT economics, a wide range of machining parameters, and multi-objective optimization still need to be considered in order to make AWJT the most economical and alternative tool for machining.

#### **5.2 AWJ milling**

Milling is one of the important alternative machining operations that can be performed by AWJ. AWJ milling has been systematically utilized where conventional machining of material is insufficient to apply. The capability of AWJ in cutting complex shapes with controlled depth has witnessed the success of AWJ milling. Recent studies have proven AWJ technology as the best alternative for milling manufacturing standard flat tensile specimens [52]. In earlier days conventional milling was the only method which was accepted internationally for manufacturing of standard sheet-type tensile specimens. Drawbacks of conventional milling in manufacturing flat tensile specimens, such as difficulties in clamping of thin sheets, requirement of milling tool with same diameter as filler radii of the tensile specimen, contouring several times to obtain desired shapes etc., have created circumstances to choose alternative nontraditional methods [53].

Advantages such as lesser manufacturing time, reasonable material removal rate, and minimal deformation stress made AWJ milling a viable alternative for conventional milling. Feasibility of AWJ in milling was first proposed by Hashish in 1989 [54]. Investigations on volume removal rates and surface finish of different materials such as titanium, aluminum, and Inconel were made through linear cutting experiments. Cutting parameters such as traverse speed, number of passes, etc. were varied at different levels. Results were compared with other methods, and some of the critical observations noted from the results are listed below:

**75**

*Abrasive Water Jet Cutting: A Risk-Free Technology for Machining Mg-Based Materials*

• Waterjet nozzles that are used for slot cutting are sufficient to do milling

*Profile of helical gear produced by AWJ (a) logo in AM60 Mg alloy, (b) spur gear profile in AM60 Mg alloy,* 

• Reasonable material removal rates can be achieved by AWJ milling with

• In terms of energy utilization for material removal, AWJ milling is the most

**Figure 11** shows some of the complex shapes (a) and profiles of helical (b) and

Present study gives comprehensive overview of abrasive water jet cutting technology for machining Mg-based materials and Mg-MMCs. Penetration capability of AZ91 and Mg nanocomposites was investigated through linear cutting experiments. Drilling of holes with different sizes in AZ91 was performed using conventional drilling and jig boring and compared with holes drilled by AWJ. These experimental investigations on machining operations such as linear cutting and drilling have revealed suitability and capability of AWJ. The present study also highlighted the application areas of AWJ in milling and turning of different materials including MMCs. However experimental investigations made in the present study was preliminary and requires detailed process economics, optimization, and comparative studies to extend and explore research possibilities. Performance, capability, and applications of AWJ in machining different grades of Mg and Mg-MMC can be

• AWJ machining is environmentally acceptable and safe.

further extended with the use of advanced modeling techniques.

*DOI: http://dx.doi.org/10.5772/intechopen.85209*

operations.

*and (c) cast iron helical gear profile.*

**Figure 11.**

**6. Conclusion**

relatively low power levels.

efficient method over other methods.

spur gear (c) produced by AWJ milling.

*Abrasive Water Jet Cutting: A Risk-Free Technology for Machining Mg-Based Materials DOI: http://dx.doi.org/10.5772/intechopen.85209*

#### **Figure 11.**

*Magnesium - The Wonder Element for Engineering/Biomedical Applications*

*Tensile specimens produced by AWJ in Mg-B4C MMC [49].*

removal rate [49]. Investigations on samples of Mg-boron carbide MMC, glass, and aluminum concluded suitability of AWJ for performing alternative machining

Preliminary investigations on AWJT has revealed that AWJ turning is less sensitive to the type of material being machined unlike conventional machining, no microstructural changes were observed on AWJ machined surfaces, tensile properties of cylindrical specimens turned by AWJ remains unaffected, and relative insensitivity of AWJ to length-to-diameter ratio of work piece enables the process to turn long and small diameter components. **Figure 10** shows the tensile test Mg-B4C MMC specimens produced by AWJT. No appreciable microhardness changes were observed during turning of Mg-B4C MMC and aluminum. No ignition issues were

Investigations conducted by the University of Rhode Island [50, 51] have witnessed machining of screw threads on composite materials. Furthermore, it was revealed that a thread produced by AWJ has an excellent potential to provide sufficient joint strength when compared to adhesive bonded joints. Minimal structural damage on machined surfaces was observed during microstructural examinations. Still there are plenty of research opportunities which are open in AWJT field to expand the applications of AWJ in different areas. Detailed studies on AWJT economics, a wide range of machining parameters, and multi-objective optimization still need to be considered in order to

Milling is one of the important alternative machining operations that can be performed by AWJ. AWJ milling has been systematically utilized where conventional machining of material is insufficient to apply. The capability of AWJ in cutting complex shapes with controlled depth has witnessed the success of AWJ milling. Recent studies have proven AWJ technology as the best alternative for milling manufacturing standard flat tensile specimens [52]. In earlier days conventional milling was the only method which was accepted internationally for manufacturing of standard sheet-type tensile specimens. Drawbacks of conventional milling in manufacturing flat tensile specimens, such as difficulties in clamping of thin sheets, requirement of milling tool with same diameter as filler radii of the tensile specimen, contouring several times to obtain desired shapes etc., have created circum-

Advantages such as lesser manufacturing time, reasonable material removal rate, and minimal deformation stress made AWJ milling a viable alternative for conventional milling. Feasibility of AWJ in milling was first proposed by Hashish in 1989 [54]. Investigations on volume removal rates and surface finish of different materials such as titanium, aluminum, and Inconel were made through linear cutting experiments. Cutting parameters such as traverse speed, number of passes, etc. were varied at different levels. Results were compared with other methods, and

some of the critical observations noted from the results are listed below:

make AWJT the most economical and alternative tool for machining.

stances to choose alternative nontraditional methods [53].

**74**

operations.

**Figure 10.**

observed during machining.

**5.2 AWJ milling**

*Profile of helical gear produced by AWJ (a) logo in AM60 Mg alloy, (b) spur gear profile in AM60 Mg alloy, and (c) cast iron helical gear profile.*


**Figure 11** shows some of the complex shapes (a) and profiles of helical (b) and spur gear (c) produced by AWJ milling.
