Debajyoti Bhaduri

Electro Discharge Machining of Titanium Nitride-Aluminium Oxide Composite for Optimum Process Criterial Yield

Titanium nitride-aluminium oxide (TiN–Al2O3) is a new generation ceramic composite material having potential for many industrial applications as it possesses high resistance to thermal degradation, anti-wear and anti-abrasion properties. But conventional machining of such ceramic composite is difficult to perform for some of its peculiar properties like anisotropy, low thermal conductivity, and abrasive nature of the reinforcing phases. In the present investigation, non-conventional machining like electro discharge machining (EDM) has been carried out to machine the material. Energy dispersive X-ray spectroscopy and X-ray diffraction analysis have also been carried out on the composite matrix to verify the presence of two distinguishable phases of TiN and Al2O3. The present article reports the effects of EDM process parameters on material removal rate, electrode wear rate, radial overcut, and taper angle while machining TiN–Al2O3 composite. The characteristic features of the EDM process are explored through Taguchi L9 orthogonal array design–based experimental studies with various process parametric combinations. Finally, optimum parameter settings for each response factor are obtained and tested through verification experiments. The whole experimental study indicates that EDM has a very good potential in machining of TiN–Al2O3 ceramic composite in some particular ranges of process parameters.

Influence of Grinding Parameters and Substrate Bias Voltage in Dry Surface Grinding with TiN-Coated Single Layer Galvanic cBN Wheel

According to some patented literatures, grit pull-out in single layer galvanic wheels can be arrested by a physical vapor deposited (PVD) coating on the wheels. It has been assumed, therein, the uniform high energy bombardment of TiN caused a reinforcement of the bond as well as increased the stability of the cBN layer on the core. However, an in-depth study on the performance of PVD coated grinding wheel is still lacking. The present research deals with exploring the effect of grinding parameters and substrate bias voltage on the performance of TiN coated galvanic cBN wheels compared to their uncoated counterpart in dry surface grinding of AISI 52100 hardened bearing steel. TiN was deposited at the bias voltages of 0, −60, and −90 V in an in-house PVD coating system. The coating microstructure and post-grinding condition of the wheels were observed using scanning electron microscopy (SEM) and phase detection was carried out using grazing incidence X-ray diffraction (GIXRD). With the increase in negative bias voltage, highly dense and compact structure of TiN was observed along with a reduction in column size. GIXRD indicated the formation of nickel-titanium intermetallics at the interface of TiN and nickel bond. Amongst the grinding parameters, downfeed was found to be the most influential factor on the grinding forces and specific grinding energy. Both downfeed and wheel velocity exhibited significant percentage contributions to the maximum grit depth of cut. The uncoated wheel was found to undergo many grit fractures and some pull-out during grinding. TiN deposited at 0 V bias could not prevent the fracture. However, when TiN was deposited at the bias voltages of −60 V and −90 V, such failures were noticeably restricted due to the high energy ion-bombardment and diffusion of Ti and TiN within the nickel bond and the cBN grits.

Pareto Optimization of Electro Discharge Machining of Titanium Nitride-Aluminium Oxide Composite Material Using Genetic Algorithm

Titanium nitride-aluminium oxide (TiN-Al2O3) is a new generation ceramic composite material having potential for many industrial applications as it possess high resistance to thermal degradation, anti-wear and anti-abrasion properties. In the present research the characteristic features of EDM process are explored through Taguchi methodology based experimental studies with various process parametric combinations. Finally the process has been optimized using Genetic algorithm based Pareto optimization search. From Pareto optimal search the technology guideline for optimal parameter settings have been selected. The present research approach is extremely useful for maximizing the productivity while maintaining the geometrical accuracy within desired limit.

Generic software tool for counteracting the dynamics effects of optical beam delivery systems

Laser micro-machining is a promising manufacturing solution for fabricating complex micro-engineering products in wide range of materials that incorporate different multi-scale functional features. Optical beam deflector systems are key components in laser micro-machining systems, and they are one of the main factors determining the processing speed and hence machining throughput. However, their performance is speed dependent and the negative dynamics effects have a direct impact on the laser micro-machining accuracy, repeatability and reproducibility. This article presents a generic software solution for minimising these negative dynamics effects, thus improving significantly the laser machining performance across the full range of available processing speeds. In particular, these improvements are achieved by introducing machine-specific compensations in machining vectors to counteract beam deflectors’ inertia regardless of their directions, length and set process speed. An empirical model was developed to obtain data about the actual dynamic response of the beam deflection system across the full range of available processing speeds, and then based on these data, the proposed generic software was implemented into a stand-alone ‘adaptive’ postprocessor. The generation of machine executable part programs is automated, and it is only necessary for the user to enter the selected scanning speeds and beam diameters. Experimental validation was conducted to demonstrate the capability of the proposed software tool. The results demonstrate that substantial improvements can be obtained in machining quality by maintaining a constant pulse distance throughout the machining operations, while the dimensional accuracy is maintained across the available processing speeds without sacrificing the machining efficiency.

Research on the Ultrasonic Assisted WEDM of Ti-6Al-4V

An investigation was made for application of ultrasonic vibration in electro discharge machining (EDM) and wire EDM, and only the vibration of wire was found to have been applied on WEDM. This paper studied on the effect of workpiece vibration to the WEDM process. The horizontal vibration of Ti-6Al-4V was applied on the rough cutting process of WEDM to study the variation of kerf width, machining rate and surface roughness. The results show that the workpiece vibration of WEDM has different effect with the wire vibration, which can improve the machining rate and kerf width, but increase the surface roughness.

Performance evaluation of a hard composite solid lubricant coating when dry machining of high carbon steel

ABSTRACT A novel hard composite solid lubricant coating combining TiN and MoSx has been developed using pulsed DC closed-field unbalanced magnetron sputtering (CFUBMS). The tribological and mechanical properties together with their interdependencies with the coating microstructures have been assessed and reported elsewhere. This article evaluates the machining performance and correlates the underlying tribological aspects of different TiN-MoSx coating architectures (deposited at titanium (Ti) cathode currents of 1, 3.5, and 5 A) when dry turning AISI 1080 high-carbon steel. A comparative performance study clearly established the supremacy of the composite coating (deposited at 3.5 A Ti cathode current with ∼12 wt% of MoSx) with a hard TiN underlayer over monolayer TiN, MoSx, and other related coating architectures in terms of cutting force, tool wear, and workpiece surface roughness. The superlubricity behavior of the said composite coated tool resulted in a reduction of cutting force (by up to ∼45% compared to the uncoated tool) and exhibited a tool life of 8 min, which was eight times and more than two times longer than that of the uncoated and conventional hard TiN coated counterparts, respectively. The workpiece surface roughness, Ra, also decreased by 13 to 21% when machined with the TiN-MoSx coated tool in comparison to the uncoated cemented carbide.