The following list of publications by our team reflect our research at the Institute
Mathematical modeling and simulation of generation milling process to manufacture complex face gear surface through multi-axis machine kinematics
Prasmit Kumar Nayak, G.L. Samuel, M.S. Shunmugam
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.
Near-infrared femtosecond laser direct writing of microchannel and controlled surface wettability
Sanasam Sunderlal Singh & GL Samuel
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.
Design and fabrication of a polydimethylsiloxane device for evaluating the effect of pillar geometry and configuration in the flow separation using deterministic lateral displacement
Pavan Pandit, Lingxue Kong & G. L. Samuel
The advancement of microfluidics and the manufacturing of microdevices has led to a strategic change in the biomedical industry. The flow through narrow channels and the pillars are placed strategically, leading to the phenomenon of particle separation through deterministic lateral displacement (DLD). In such a phenomenon, the shape, size, location and orientation of the obstacles play an important role. For the first time, particle separation is achieved with DLD modules having high row shift angles of 25°, 30° and 35°, reducing the number of pillars. The significance of circular and triangular micropillars executing deterministic lateral displacement, oriented at different angles, has been investigated, and it is found that the triangular pillars oriented at 75° resulted in better separation compared to the other configurations. In this report, the fabrication, location, orientation of the micropillars and the selection of appropriate process parameters are detailed. The structures are fabricated on silicon wafers using the standard photolithography process followed by the deep reactive ion etching process. These dies are further used to fabricate the polydimethylsiloxane-based microfluidic chips. These fabricated devices are characterised by their size, structure and quality using 3D microscopy and scanning electron microscopy. Further, blood plasma separation is carried out using the devices fabricated in this work, and the particles at the inlet and outlets are evaluated using microscopy and a novel image processing technique, replacing the use of a hemocytometer. The path traced by the particles at different flow conditions is numerically evaluated and validated with experiments. The novel device is capable of separating blood cells from plasma with a recovery factor varying from 44% to 100%. PDMS–PDMS bonding experiments using oxygen and argon plasma have been carried out to evaluate the maximum bond strength and flow velocity in the devices. It is observed that the oxygen plasma results in a bond strength of 0.404 N mm−1, thus a high throughput of 135.34 μL s−1 is achieved using the fabricated device.
Modelling and validation of surface roughness in micro-turned nickel-based alloys (Nimonic 90)
Vineet Kumar, GL Samuel
Monitoring of material-removal mechanism in micro-electrical discharge machining by pulse classification and acoustic emission signals
K Goswami, GL Samuel