Search

Laser beam cutting of Inconel 625 superalloy with a Nd:YAG laser in a submerged condition has been studied here. The effect of the underwater laser beam cutting parameters such as lamp current, pulse frequency, pulse width, cutting speed, height of water column on Kerf width and depth of cut are investigated using response surface methodology (RSM). The developed mathematical models are tested by analysis of variance (ANOVA) method to check their adequacy. The central composite design (CCD) technique based on RSM is employed here to carry out the experiments to achieve optimum responses with a reduced number of experiments. From the ANOVA analysis it is found that pulse frequency is the most dominant factor. Height of water column has great impact on quality characteristics of the cut zone. [ABSTRACT FROM AUTHOR]

Nd:YAG lasers are widely used in metal cutting industries; however, they have not yet been fully exploited in creating micro-features on samples because of high heat affected zone (HAZ) and uncontrolled material removal. In this work a Nd:YAG laser has been utilized in creating microchannels on polymethylmethacrylate (PMMA) in submerged water condition. Taguchi methodology with L-16 orthogonal array design has been chosen for performing the experiments. Lamp current, scanning speed, pulse frequency and pulse width has been selected as input process parameters. Width and depth of the microchannels have been taken as output quality characteristics. Analysis of variance has been performed for each quality characteristics to check the compatibility of this methodology. Each quality characteristics has been optimized using Taguchi's technique. Multiple quality characteristics have been optimized using grey based Taguchi technique. Grey based Taguchi technique provides efficient and effective way to optimize the process based on grey relational grades. Underwater laser processing resulted in lowering heat affected zone (HAZ) and debris formation therefore producing clean structures than air. Experiments showed that the process can be readily used in micromachining facilities to create micro-features on materials. [ABSTRACT FROM AUTHOR]

The current research elaborates an experimental study on poly (methyl methacrylate) (PMMA), to produce microchannels using the laser transmission cutting technique, utilizing a nanosecond pulsed Nd:YAG laser system. The cutting operation was carried out in partially submerged condition. The prime objective during the machining operation was to minimize the heat affected zone (HAZ) and kerf width. Lamp current, pulse frequency, pulse width and cutting speed were the process parameters under consideration during the experimentation. The developed microchannels characteristics such as HAZ and kerf width were subsequently measured and analysed. Response surface methodology (RSM) technique was applied to develop the mathematical relationships between the input process parameters and output responses. Model adequacy was tested using the method of analysis of variance (ANOVA). The optimal combinations of process parameter settings were obtained through single and multi-objective optimizations methods. [ABSTRACT FROM AUTHOR]

• Carried out Nd:YAG laser micro-drilling operations on gamma titanium aluminide. • Observed quality characteristics of through micro-drilled holes. • Proposed a combined Fuzzy-TOPSIS and RSM technique for parametric optimization. Multi criteria decision making methods and response surface methodology based approaches are invariably utilized in improvement of quality in several manufacturing industries. This paper presents the technique to determine optimal process parameters during micro-drilling using Nd:YAG laser source on gamma titanium aluminide alloy using fuzzy-TOPSIS (fuzzy-technique for order preference by similarity to ideal solution) and RSM (response surface methodology) together. A new alloy, Gamma-titanium aluminide (Ti-44.5, Al-2, Cr-2, Nb-0.3B (at%)) has been chosen for experimentation. This material possesses desirable qualities like very high hardness, high strength temperature resistant, high yield stress and ultimate strength in tension, good creep, very low density, resistance to oxidation etc., found applications in technologically advanced industries like spacecrafts, aerospace, nuclear power plants, electronics, automobiles etc. A model has been developed which can be used for decision making in identifying the optimum laser parameters like lamp current, pulse frequency, air pressure and thickness of the workpiece, which affect several quality aspects of micro-machined job such as hole circularity at entry, hole circularity at exit and taper of drilled hole. Triangular fuzzy numbers are being utilized to calculate weighting factor of each machining criterion. Also, the combination of most desirable factor levels has been obtained using a fuzzy-TOPSIS method. [ABSTRACT FROM AUTHOR]