Informatics Publishing Limited

G. Kibria ¹, B. Doloi ², B. Bhattacharyya ²

Affiliations
1 Mechanical Engineering Department, Aliah University, Kolkata-700091, IN
2 Production Engineering Department, Jadavpur University, Kolkata-700032, IN

Abstract

Laser micro-turning process is one of the newly developed laser material processing technologies to generate micro-turned groove or surface on cylindrical workpiece. In the present paper, an attempt has been made to investigate the laser micro-turning operation on cylindrical shaped aluminium oxide (Al₂O₃) ceramic to study the influence of different laser micro-turning process parameters namely, laser average power, pulse frequency, workpiece rotational speed, assist air pressure and Y feed rate using response surface methodology (RSM) experimental plan. The mathematical model for surface roughness (Ra) has been developed and the adequacy of the model has been tested through analysis of variance (ANOVA) results. Average power and pulse frequency are the most significant process parameters. Optimal parametric combination for minimum value of surface roughness has been achieved as 5.23μm at parametric setting of average power of 9.04 W, pulse frequency of 4108.18 Hz, workpiece rotational speed of 451.16 rpm, air pressure of 1.44 kgf/cm² and Y feed rate of 0.37 mm/s. Confirmation experimental results show a good agreement between RSM based optimal and experimental value of response criterion.

Keywords

Laser Micro-Turning, Surface Roughness, Alumina, Response Surface Methodology.

Full Text

     

G. Kibria ¹, B. Bhattacharyya ²

Affiliations
1 Mechanical Engineering Department, Aliah University, Kolkata-700091, IN
2 Production Engineering Department, Jadavpur University, Kolkata-700032, IN

Abstract

Micro-electrical discharge machining (μEDM) deals with micro dimensional material removal from the work sample due to the repetitive spark discharge between the micro-tool electrode and the workpiece. In the present paper, an attempt has been made to machine through micro-holes on Ti-6Al-4V superalloy plates to investigate the effect of mixing of Boron Carbide (B₄C) powder additive in kerosene dielectric. A detailed comparative study has been made showing the effect on micro-ED machining criteria i.e. material removal rate (MRR), tool wear rate (TWR), overcut (OC) and taper by varying two most influencing micro-EDM process parameters i.e. peak current and pulse-on-time keeping other parameters such as flushing pressure, duty ratio, gap voltage, etc. as constant. It has been found that B₄C powder can enhance material removal rate while it can reduce tool wear rate. Analyses have also been done showing some optical and SEM micrographs of the micro-tool electrode tips as well as machined micro-hole walls to study the micro-hole surface features during experimentation.

Keywords

Micro-EDM, Ti-6Al-4V, Boron Carbide Additive, MRR, TWR, Overcut, Dielectric.

Full Text

     

G. Kibria ¹, B. Doloi ², B. Bhattacharyya ²

Affiliations
1 Mechanical Engineering Department, Aliah University, Kolkata, IN
2 Production Engineering Department, Jadavpur University, Kolkata, IN

Abstract

The present paper addresses the laser micro-turning process of aluminium oxide (Al₂O₃) ceramics of size 10 mm in diameter and 40 mm in length. The experiments have been conducted using response surface methodology design of experiments. The targeted depth was set at 100 μm. Laser average power, pulse frequency, workpiece rotating speed, air pressure and Y feed rate were considered as process variables. After each experiment, surface roughness (Ra) and micro-turning depth deviation have been measured. Multi-objective optimization has been done to obtain optimal values of responses i.e. surface roughness and depth deviation. To achieve further high quality machined surface, machining was done at various defocusing conditions of laser beam and also by varying the number of laser scan passes. Other parameters were kept constant at optimal parametric combination obtained in multi-objective optimization. From the experimental results, it was revealed that surface roughness decreases with increase in defocusing positions. With increase in number of passes up to a certain limit, surface roughness decreases. However, depth deviation increases with number of laser scan passes at all levels of defocus planes.

Keywords

Pulsed Nd:YAG Laser, Laser Micro-Turning, Surface Roughness, Advanced Ceramics, Aluminium Oxide (Al₂O₃), Defocusing Positions.

Full Text

     

G. Kibria ¹, B. Doloi ¹, B. Bhattacharyya ¹

Affiliations
1 Prod. Engg. Dept., Jadavpur University, Kolkata, IN

Abstract

Laser beam machining (LBM) is a non-contact type of material removal process and this advanced thermal machining process is extensively used worldwide in material processing field in modern industries. The high density focused laser beam melts and vaporizes the unnecessary portion of parent material very efficiently. During the last decades, a number of researchers have explored experimentally and theoretically this Nd:YAG laser beam machining technique with different materials like metals, alloys, ceramics and composites through a number of ways to improve the machining performances. The paper reviews the research works performed in the area of Nd:YAG laser micromachining operations such as micro-drilling, microgrooving, micro-cutting, micro-milling, micro-turning and marking etc. on aduanced engineering ceramics for searching out the various micro-machining process parameters and their effects on laser machining performance characteristics.

Full Text