Performance and Surface Evaluation Characteristics on Cryogenic-Assisted Abrasive Water Jet Machining of AISI D2 Steel

Performance and Surface Evaluation Characteristics on Cryogenic-Assisted Abrasive Water Jet Machining of AISI D2 Steel

Yuvaraj N. (Vel Tech Rangarajan Dr. Sagunthala R&D Institute of Science and Technology, India) and Pradeep Kumar M. (Anna University, India)
Copyright: © 2019 |Pages: 30
DOI: 10.4018/978-1-5225-6161-3.ch010

Abstract

The chapter reports on the investigation of cryogenic-assisted abrasive water jet (CAAWJ) machining of AISI D2 steel with varying the jet impact angles and abrasive mesh sizes. The performance measurement is considered in this study such as depth of penetration and taper ratio. Also, the surface integrity characteristics are considered in the present study such as abrasive contamination, surface topography, XRD peaks, residual stress, and micro hardness. The CAAWJ machining process improves the performance measurement such as higher depth of penetration and lower taper ratio for the machining of D2 steel. Also, the CAAWJ cut surface consists of better surface integrity features over the AWJ cut surface. The phase transformation effect of target material under cryogenic cooling helps to turn the mode of the material removal mechanism from ductile to brittle erosion process and yield a better performance. The results also indicate that the oblique jet impact angles have been produced better performance characteristics than the jet impact angle of 90o at room temperature.
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Background

Despite several benefits seen, AWJ has some limitations such as generation of a higher volume of secondary wastages, lower cutting efficiency, nozzle wear, striation formation, abrasive contamination, etc (Kuleki, 2002), causing a low depth of penetration, poor taper cut ratio and loss of surface integrity. As a result, the use of AWJ is limited in manufacturing industries. A few researchers have developed techniques which include nozzle oscillation, changing jet impact angle and abrasive mesh size, etc (Aich et al., 2013). These techniques were developed for restrict the defects seen on the AWJ machined surface such as abrasive contamination, wear tracks, striation formation and taper formation. However, the significant results are not yet obtained by researchers and scientists while machining hard materials.

A wide variety of materials can be machined by AWJ, only very few of them have reported comprehensive details of the cutting performance and surface integrity characteristics. However, a few hard materials were less machined by AWJ such as die steels, tool steels, Inconel, etc. Some results observed on the AWJ machined die and tool steels are summarized below.

Asif et al. (2011) have investigated the AWJ cutting of 4340 tool steel and Aluminium 2219. The thicknesses of the work material were 20 mm and 40 mm. They reported reduction in the roughness of the cutting wear zone through decrease in the traverse speed arising from sufficient contact time between the target material and abrasives. This consequence happened owing to the large number of abrasive particles employed in the cutting action. The result also indicated that the traverse rate and target material thickness as the most influencing factors for tool steel materials. Ankush and Lalwani (2013) reported the investigation of AWJ machined H13 die steel with a thickness of 12 mm and better surface finish obtained under a lower traverse rate along with a higher stand-off distance and with water jet pressure employed in the cutting process. Traverse rate as the significant parameter for the AWJ machining of die steel has been indicated. Zhao and Guo (2014) investigated the AWJ machined surface features in cold work mold steel, 6061 aluminium alloy, high strength low alloy steel and AISI 304 stainless steel. They reported the ductility of the material causing severe wear traces caused on the target material surfaces during the machining process.

Deepak et al. (2015) made a study of the jet penetration and taper angle in cutting of D2 steel by an AWJ with a thickness of 8 mm. The cutting experiments were carried out through variations in the water jet pressures. Depth of penetration was seen increasing with increase in water jet pressure. Lower water jet pressure did not produce any through cut in the work material. Moreover, they found an increase in water jet pressure with a decrease in taper cut. Hlavac et al. (2015) investigated the taper angle in various grades of AWJ machined steel with a thickness of 30 mm. They found the variations in taper cut, and curvatures in the entry of kerf wall cut surface formed by the ductility of the steel leading to the deformation induced by the ductile work materials during the cutting process.

Key Terms in this Chapter

Performance Characteristics: The quantitative responses are the depth of penetration, material removal rate, kerf width, and surface roughness considered as performance characteristics.

Liquid Nitrogen: It is a safe refrigerant and is used for safe environmental machining operations. It is colorless, odorless, and non-corrosive.

Cryogenics: It is a low-temperature substance and is used for improving the material properties in a beneficial manner at low temperature.

Abrasive Water Jet: It is a mechanical based cold machining technique. It is mainly used for machining very hard materials. The material removal takes place through a high velocity jet erosion mechanism.

D2 Steel: Steel is more suitable for cryogenic machining operations as modified and beneficial erosion mechanism attained easily at cryogenic temperature.

Surface Characteristics: The qualitative variables are the surface morphology, contamination, topography, micro structure, residual stress, and hardness considered as surface integrity characteristics.

Surface Integrity: It influences the functionality of the machined components in various applications. The elements enclosed in the modified machined surface is characterized as integral.

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