Publications

Precision ball bearing applications have demanding operating conditions of low friction, variable speeds and high lifetimes. Even though the primary mode of operation in such bearings is Elasto-Hydrodynamic Lubrication (EHL) regime, they undergo transitions between EHL, mixed & boundary lubrication conditions and contact skidding due to accelerations/ deceleration cycles at high speed. The performance and life of these bearings can be improved by developing new lubricant formulations, surface coatings, surface texturing etc. Laser Surface Texturing (LST) of bearing rings using pulsed laser beams is a viable option for improving the tribological properties of bearings. The criticality in developing textures for precision bearing races is to produce burr free shallow micro-textures. This study attempts to design, generate and characterize micro-textures in hardened martensitic AISI 440C steel plates for precision …

Laser surface texturing is an advanced fabrication technique employed to create microfeatures on material surfaces, enhancing their tribological properties. This study investigates the use of femtosecond laser surface texturing (100 fs pulse duration, 800 nm wavelength) to produce micro-crosshatch patterns on gray cast iron substrates, with the objective of improving friction and wear performance. The effects of critical process parameters, including texture density and aspect ratio, on tribological behavior were systematically examined. Surface morphology and topography were characterized using opto-digital 3D microscopy and field emission scanning electron microscopy (FESEM). Structural and morphological alterations in the textured gray cast iron surfaces, including the exposure of open-structured graphite flakes and the formation of graphite films within the textured regions, were observed. Tribological …

This study investigates the micromachining of microchannels on silicon surfaces using a femtosecond pulsed laser with an 800 nm wavelength and 100 fs pulse duration. The process parameters were modeled and optimized using the Response Surface Methodology based on the Box-Behnken design to enhance machining precision and efficiency. The effects of laser power, scanning speed, and line spacing on depth, surface roughness, and material removal rate were systematically evaluated. Results showed that higher laser power (up to 750 mW) significantly increased MRR, whereas lower power (eg, 50 mW) reduced material removal. Scanning speed inversely affected machined depth, while line spacing (5–15 μm) strongly influenced machining outcomes through parameter interactions. The highest material removal rate of 1.18× 10 6 μm 3 s− 1 was achieved under optimized conditions. Validation …

Ultrafast laser processing is a highly versatile tool for creating microscale structures in many materials. The ablation and micromachining characteristics of AISI 304 stainless steel were examined using a femtosecond-pulsed laser. Parameters such as power, scanning speed, transverse overlap, scanning strategies, and shielding gases were systematically varied. The ablation threshold fluence for SS 304 was calculated as 0.16 J/cm2. Two ablation regimes were observed: the gentle regime, where smooth crater walls were formed under low pulse energy (below 20 µJ), and the strong regime, characterized by rough walls created under high pulse energy (above 20 µJ). The optimal parameters for fabricating microchannels on SS 304 surfaces comprised a laser power of 100 mW, a scanning speed of 30 mm/s, a line-to-line distance of 5 µm, and a parallel scan strategy along the major axis. This study provides a practical approach for enhancing the microchannel fabrication process on stainless steel.

Ultrafast laser processing enables the fabrication of microscale structures in diverse materials without inducing heat‐affected zones. The ablation and micromachining properties of polycarbonate were investigated using a femtosecond‐pulsed laser with an 800 nm wavelength and a 100 fs pulse duration. Ablation threshold fluence was determined to be 0.0112 J/cm2. Response Surface Methodology based on the Box–Behnken design was applied for the optimization of the conditions of the micromachining process with respect to laser pulse energy, scanning speed, and line spacing. An increased rate of material removal by a higher laser power of 800 mW decreased in the case of the lower power of 100 mW. Line spacing became very critical because while varying from 5 to 15 μm, it resulted in a different machining pattern. An increased scanning speed decreased the machined depth. The highest material …