Ishan Saxena

Machining of Carbon Fiber Reinforced Plastics/Polymers: A Literature Review

Carbon fiber reinforced plastics/polymers (CFRPs) offer excellent mechanical properties that lead to enhanced functional performance and, in turn, wide applications in numerous industrial fields. Post machining of CFRPs is an essential procedure that assures that the manufactured components meet their dimensional tolerances, surface quality and other functional requirements, which is currently considered an extremely difficult process due to the highly nonlinear, inhomogeneous, and abrasive nature of CFRPs. In this paper, a comprehensive literature review on machining of CFRPs is given with a focus on five main issues including conventional and unconventional hybrid processes for CFRP machining, cutting theories and thermal/mechanical response studies, numerical simulations, tool performance and tooling techniques, and economic impacts of CFRP machining. Given the similarities in the experimental and theoretical studies related to the machining of glass fiber reinforced polymers (GFRPs) and other FRPs parallel insights are drawn to CFRP machining to offer additional understanding of on-going and promising attempts in CFRP machining.

High-speed fabrication of microchannels using line-based laser induced plasma micromachining

Microtexturing of surfaces has various applications that often involve texturing over large (macroscale) areas with high precision and resolution. This demands scalability and speed of texturing while retaining feature sizes of the order of a few microns. Microchannels are a versatile microfeature, which are often used in microfluidic devices and can be arrayed or joined to form patterns and free-form geometries. We present a technique to fabricate microchannels on surfaces with high-speed and by using a multimaterial process, namely, laser induced plasma micromachining (LIPMM). The process has the potential to machine metals, ceramics, polymers, and other transparent, brittle, and hard-to-machine materials. The presented technique uses an optical system to modify the laser spot into the shape of a line, to fabricate microchannels directly without scanning as in the case of a regular circular spot. The process schematics are shown, and micromachining experiments on polished aluminum are discussed. Moreover, it is shown that the depth and width of the channels may be varied by changing process parameters like the pulse energy, pulse frequency, and number of exposures.

Laser-induced plasma in aqueous media: numerical simulation and experimental validation of spatial and temporal profiles

A numerical study of spatial and temporal distribution of a Gaussian-pulsed laser-induced plasma in distilled water is conducted in order to understand the resulting electron density distribution within the plasma plume. The primary motivation behind this study is the recent impetus on laser-induced plasma in the field of microfabrication, where prediction of geometric feature information is paramount to understanding material removal and overall process performance. This simulation predicts the distribution of plasma energy density, absorption coefficient, and laser intensity within the focal region by using a 3D axisymmetric model. The model can be adapted to other nonaqueous condensed media and different laser wavelengths and pulse widths. This numerical model was experimentally validated by an ultrafast gated camera and an external power meter by measuring the plasma energy and residual intensity, respectively. The model and the experimental data show similar qualitative trends in plasma energy density as the beam power is increased. Also the residual intensity data obtained from the model is within 10% of the experimental data for near-threshold intensities and within 40% for super-threshold intensities. The outcomes of this model can be further used as an input for a hydrodynamic model to predict the behavior of the condensed medium or for a thermomechanical model to predict material removal characteristics of the plasma.

Laser-Induced Plasma Micromachining Process: Principles and Performance

Laser-induced plasma micromachining (LIP-MM) is a novel multimaterial and tool-less micromachining process. It utilizes tightly focused ultrashort laser irradiation to generate plasma through laser-induced dielectric breakdown in a dielectric material. The plasma facilitates material removal through plasma–matter interaction spot through vaporization and ablation. The paper introduces the LIP-MM process, discusses the underlying principles behind plasma generation and machining, and proves its feasibility by describing the experimental conditions under which plasma generation and machining occur. Upon successful commercial realization of this novel process, the key benefits envisaged are micromachining with better accuracy and better surface integrity, minimal subsurface damage, relatively smaller heat-affected zone (HAZ) and low roughness in a wide range of materials including those that are difficult to machine by some of the most successful micromachining processes such as micro-electrodischarge machining (EDM) and laser ablation.

Multi-Material Capability of Laser Induced Plasma Micromachining

Presently surface micro-texturing has found many promising applications in the fields of tribology, bio-medical engineering, metal cutting, and other functional or topographical surfaces. Most of these applications are material-specific, which necessitates the need for a texturing and machining process that surpasses the limitations posed by a certain class of materials that are difficult to process by laser ablation, owing to their optical or other surface or bulk characteristics. Laser Induced Plasma Micromachining (LIPMM) has emerged as a promising alternative to direct laser ablation for micro-machining and micro-texturing, which offers superior machining characteristics while preserving the resolution, accuracy and tool-less nature of laser ablation. This study is aimed at understanding the capability of LIPMM process to address some of the issues faced by pulsed laser ablation in material processing. This paper experimentally demonstrates machining of optically transmissive, reflective and rough surface materials using LIPMM. Apart from this, the study includes machining of conventional metals (Nickel and Titanium) and polymer (Polyimide), to demonstrate higher obtainable depth and reduced heat affected distortion around micro-features machined by LIPMM, as compared to laser ablation.Copyright

Line-Based Laser Induced Plasma Micro-Machining (L-LIPMM)

Recently, the technique of Spot-based Laser Induced Plasma Micro-Machining (Spot-LIPMM) has been developed to address the limitations of conventional ultrashort pulse laser micro-machining. Its main advantages are adaptability to a wide range of materials and superior wall geometries. We propose a variation of the Spot-LIPMM process by creating line plasma instead of spot plasma, with the use of suitable optics. This paper describes the experimental setup used to create line plasma and the process used for micro-machining with L-LIPMM. Optics simulations are developed as a means of guiding the choice of optics to be used for line plasma generation and estimating the energy and shape of the plasma created. It is shown that this Line-based LIPMM (L-LIPMM) process is capable of micromachining channels at a much higher speed than conventional Spot-based laser ablation or spot-based LIPMM. Additionally, the effects of process parameters on machined geometry using L-LIPMM are discussed.Copyright