Publications

Effect of pulse repetition rate on synthesis of TiOx nanoparticles by femtosecond pulsed laser ablation in aqueous medium

Microfluidics finds a wide range of industrial applications mainly in fields such as biomedical, clinical, electrical, and thermal engineering. Microchannels are the building blocks of most microfluidic devices. Thus, it becomes evident to understand the properties and the effect of the surfaces on the outcomes of devices. In this study, the effect of the shape of microchannels and the roughness elements on the flow is evaluated. Microchannels with three cross-sections and roughness elements of three different geometries are considered. The effect of varying Reynolds numbers on the flow parameters such as Friction factor, Nusselt number, Poiseuille number, pressure drop and surface temperature at the base of the substrate is studied. It is observed that rough microchannels and rectangular roughness elements showed a higher Nusselt number than smooth microchannels. The rough microchannels with triangular

AISI H13 tool steel is widely used as a die material in pressure die-casting (PDC) applications. The demonstration of additive manufacturing (AM) of AISI H13 tool steel is gaining commercial interest within the tooling industry, with the objective of enhancing the service life of tools by innovating PDC tools with conformal cooling channels. Thus, in the current study, powder bed fusion using laser beam melting (PBF-LB/M) technology was used to manufacture AISI H13 tool steel using high laser power and scan speed processing parameters. Best parameter combinations termed as P1 (300 W and 1000 mm/s) and P2 (250W and 1200 mm/s) were determined from the single-track experiments and used for further multi-track and multi-layer experiments with suitable hatch spacing and layer thickness of 30 µm. The AM-built H13 tool steel samples were characterized for microstructural and mechanical properties in both as …

Manufacturing of face gear is a complex process, due to its varying geometry, hence the application is not wide as conventional gear geometry. The developments in analytical tools and kinematics of the CNC machine tools motivate researchers to explore the manufacturing process and associated applications. This article presents an efficient method for the generation milling of spur face gear utilizing a nutating head multi-axis CNC machine tool where the tool swings about an arbitrary axis in an inclined plane. The mathematical model of the disk milling cutter and face gear geometry were derived from the shaper geometry by applying the theory of gearing, equation of meshing and coordinate transformation. The cutter location (CL) data was evaluated by aligning the tool orthogonal unit vector and the tooth surface normal vector at the contact point by calculating the appropriate transformation matrices.

The application of femtosecond laser in fabricating poly (methyl methacrylate) microchannels and the alteration of wettability by inducing a change in chemical functional groups has already been established and reported in literature. However, studies on the application of femtosecond laser for modification of surface wettability without significant chemical modification, are yet to be reported. The paper reports work on an expedition of femtosecond (Ytterbium-doped fiber) laser ablation working at the near-infrared wavelength (1030 nm) tuning the wettability behavior comprising of hydrophilic and hydrophobic state on the basis of the surface morphology created below the focal beam diameter. The initial part revolves around the investigation of near-infrared femtosecond laser ablation for achieving microcavity and microchannel below the focal beam diameter. The latter part deals with laser surface modification for attaining both hydrophilic and hydrophobic surfaces. The study obtained a high degree of hydrophobicity, with a maximum water contact angle of 129.05° at a laser energy of 40 μJ and pulse laser overlap of 96%. It was also possible to attain a minimum water contact angle of 56.35° using a laser pulse energy of 40 μJ and pulse overlap of 0 %. The reported work avoids surface chemical modification for controlling the wettability.