Laser beam machining (LBM) has proven its applications and advantages over almost all the range of engineering materials. It offers its competences from macro machining to micro and nano-machining of simple-to-complex shapes. The hybrid approaches in laser ablation have demonstrated much improved results in terms of material removal rate, surface integrity, geometrical tolerances, thermal damage, metallurgical alterations and many more. The flipside of LBM is the existence of universal problems associated with its thermal ablation mechanism. In order to alleviate or reduce the inherent problems of LBM, a massive research has been done during the past decade in order to build a relatively new route of laser-hybrid processes. This paper reviews the research work carried out so far in the area of LBM and its hybrid processes for different materials and shapes. The article also highlights the research gaps and future research directions in the context of laser and laser-hybrid ablation.

Micro-channels have been fabricated in nickelbased superalloy (Inconel 718) through laser beam machining (LBM). Two machining mediums are employed: dry and wet medium. Under the dry medium, laser beam passes through air prior to strike with target surface while under wet medium, the laser beam first travels through a layer of distilled water and reaches the substrate after. For both the machining environments, effects of laser power, pulse repetition rate, and laser scan speed on machined channels' width, depth, and taperness are investigated. A comparison of parametric effects on machined channels' profiles has been carried out for the said machining conditions. The results reveal that LBM under distilled water is more productive than LBM under air environment. In one step, wet machining conditions allow to generate a set of two microchannels, and dry conditions generate one micro-channel. Further, to achieve the optimum dimensions of micro-channels, the appropriate level of each of the investigated laser parameter is proposed.

PurposeThe purpose of this paper is to investigate the potential application of electron beam melting, as a layered manufacturing process, to fabricate dental coping of metal‐ceramic crown restoration using Ti6Al4V powder.Design/methodology/approachThis experiment was conducted in two steps: shrinkage study to determine scale up factor for shrinkage compensation and parameter selection study, based on thickness, hardness, and surface roughness, to select process parameter of electron beam melting.FindingsA promising result of fabricating metal coping of Ti6Al4V via electron beam melting was shown. Ti6Al4V coping was successfully fabricated, with an average thickness of 0.52 mm required for dental coping. Total average hardness of 333.35 HV that is comparable to casted Ti6Al4V with considerably high roughness of RSm of 382 μm.Originality/valueThe paper presents a novel application of electron beam melting to fabricate metal coping for metal‐ceramic crown restoration.

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Laser ablation is one of the competent machining processes to fabricate microfeatures in variety of engineering materials. This study has been progressed to evaluate the process capability of generating microchannels of various sizes (50 Â 50 mm, 100 Â 100 mm, 200 Â 100 mm, and 1000 Â 500 mm) in titanium alloy (Ti6Al4V) using Nd:YAG laser. Channel's top width, bottom width, depth, and taperness are examined as the four process responses against three laser based parameters to the naming of laser intensity, repetition rate, and scan speed. All the geometrical dimensions are measured through photographic snapshots of SEM of each fabricated channel. The results reveal that the selection of channel size is critical to achieve the desired machining geometries. Wider sized channels (such as 200 Â 100 and 500 Â 1000 mm) are experienced as more flexible to be generated than narrower sized channels (50 Â 50 and 100 Â 100 mm). The precise parametric combination is the key to realize more tight dimensional enormities with respect to the targeted machining elements. The most appropriate parametric combinations that can generate the respectable results are explored and applied for machining of different channel sizes.