Manufacturing Technology Today

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.

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S. Das ¹, B. Doloi ¹, B. Bhattacharayya ¹

Affiliations
1 Jadavpur University, Kolkata, IN

Abstract

Micro Ultrasonic Machining is the downsized version of Ultrasonic Machining process in which material is removed from hard and brittle workpiece typically by micro-chipping. The tool vibrates at ultrasonic frequency (~20 kHz) with amplitude of 8-30 μm. Abrasive slurry containing abrasive particles flushes through the gap between the tool and workpiece. The tool is pushed on the workpiece with certain static load. The work material is directly hammered by numerous abrasive particles with kinetic energy imparted by the vibrated tool. Flushing of slurry refreshes the abrasive particles in the machining area and also removes the debris and worn abrasive particles away from the gap. During the last decades, a number of researchers have explored experimentally and theoretically this Micro USM technique with different materials. The paper reviews the research works performed in the area of Micro Ultrasonic Machining process such as machining set up, parametric analysis and applications.

Keywords

Micro Ultrasonic Machining, Material Removal Rate, Geometrical Accuracy.

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P. Josephine ¹, B. Doloi ¹, B. Bhattacharyya ¹

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

Abstract

Laser marking is one of the emerging technologies in the field of laser processing. Laser marking is the best and most applied technique to make permanent marks on a wide range of materials. Nd:YAG laser beam can be used for marking on various materials such as ceramics, metals and composites etc. This paper includes the review on research activities in the area of Nd:YAG laser marking process. The present status of Nd:YAG laser marking process will obviously generate further scope of research and development in the field of laser marking.

Keywords

Nd:YAG Laser, Laser Marking, Engineering Materials.

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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.

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H. Lalchhuanvela ¹, B. Doloi ¹, B. Bhattacharya ¹

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

Abstract

Ultrasonic machining is a material removal process which does not depend on a conductive workpiece and is preferable for machining workpieces with low ductility and hardness above 40 HRC such as engineering ceramics etc. Material removal mechanism includes impacting, hammering and cavitations. Unlike other non-traditional processes such as laser beam machining, electrical discharge machining, etc., ultrasonic machining does not thermally damage the workpiece and it avoids the significant level of residual stresses which are important for the survival of brittle materials in service. In this paper, the fundamental principles of ultrasonic machining and its combinations with other processes, the material removal mechanisms and the effects of the operating parameters on material removal rate, tool wear rate are reviewed with emphasis on engineering ceramics.

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B. Doloi ¹, N. S. Mitra ¹, A. K. Mete ¹, B. Bhattacharyya ¹

Affiliations
1 Production Engg. Dept., Jadavpur University, Kolkata-700032, IN

Abstract

Traveling Wire Electrochemical Discharge Machining (TW-ECDM) System has great potential to cut non-conducting engineering hard materials such as ceramics and composites etc. There is also an urgent need for precision machining of engineering ceramics and composites with the development of these materials. Several non-conventional machining processes are available but all of them have inherent difficulties. The traditional method of slicing glass and ceramics, quartz etc. is limited mainly due to high cutting force and requirement of utra-hard tool materials. Hence there is a need to develop an efficient method of cutting and slicing non-conducting engineering materials. Traveling Wire Electrochemical Discharge Machining (TW-ECDM) is an important useful process for this purpose. Present research paper includes the design and development of the experimental setup of total TW-ECDM system which consists of main machining chamber, mechanical hardware modules, electrolyte flow control units and electrical pulsed dc power supply unit. The operation of the developed TWECDM System has been tested after carrying out some experimentation on cutting of Silicon Nitride.

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B. R. Sarkar ¹, B. Doloi ¹, B. Bhattacharyya ¹

Affiliations
1 Production Engineering Department, Jadavpur University, Kolkata-700 032, IN

Abstract

The electrochemical discharge machining (ECDM) process is a non-conventional, thermoelectric, hybrid machining process, which uses electrochemical discharge phenomenon and has a great potential to machine an electrically non-conducting engineering ceramic like Silicon Nitride (Si3N4). The present research paper highlights on the development of a second order non-linear mathematical model that establishes a relationship between the penetration rate and different process parameters such as applied voltage, electrolyte concentration and inter-electrode gap utilising the experimentally obtained data during micro-drilling of silicon nitride by electrochemical discharge machining process. The experimentation has been conducted according to the central composite second order rotatable design based on Response Surface Methodology (RSM). The analysis of variance (ANOVA) has been performed to verify the adequacy of the aforesaid polynomial mathematical model. The parametric effects have also been studied based on the developed mathematical model for obtaining optimal penetration rate during micro-drilling of Silicon Nitride by ECDM process.

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A. S. Kuar ¹, B. Doloi ¹, B. Bhattacharyya ¹

Affiliations
1 Production Engineering Department, Jadavpur University, Kolkata-700032, IN

Abstract

A Nd:YAG pulsed CNC laser machining-system has potential for precision machining operation on very hard conductive as well as non-conductive materials. For achieving high profile accuracy, the important process parameters such as the radio frequency of Q-switch, lamp current and cutting speed are to be optimally controlled because these controllable process parameters mostly affect the precision machining i.e. dimensional accuracy and surface roughness. In this present research, a hard cutting tool material has been chosen for generating intricate and accurate shape of cutting tool and the accuracy in profile cutting and surface roughness are considered as the responses of the Nd:YAG laser cutting operation. Taguchi method based parametric optimisation is applied for determining the optimal parametric combination for achieving high quality machining characteristics during Nd:YAG laser cutting operation. The confirmation test has also been carried out to predict and verify the adequacy of the additive model for determining the optimal machining characteristics.

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