Mechanical & Materials Engineering, Department of


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A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Mechanical Engineering & Applied Mechanics, Under the Supervision of Professor Kamlakar P. Rajurkar. Lincoln, Nebraska: December, 2015

Copyright (c) 2015 Farnaz Nourbakhsh


This study presents an experimental investigation and finite element simulation of Electro Discharge Drilling (ED-Drilling) of Polycrystalline Diamond (PCD). PCD has many outstanding properties including uniformly high hardness, high wear resistance and strong corrosion which are the main causes of widely using PCD. While PCD has many advantages and an important role in industrial applications, its high level of hardness and wear resistance cause this material to be difficult to form and machine by using traditional machining methods. EDM as a nontraditional machining process is an effective method among other non-traditional methods for PCDs due to its low cost and flexibility. The objective of this study is to investigate the effect of five process parameters including voltage, spindle speed, pulse on-time, pulse current and gap size on cutting speed on Material Removal Rate. A Taguchi L18 design of experiment (DOE) has been applied to optimize the number of trivals in order to save time and raw material. All experimental trials have been conducted using ED-Drilling Hole Popper machine. EDM process is a complicated process and it is very difficult to understand the mechanism which involves electrodynamics, thermodynamic and hydrodynamic. Hence to understand the process and to identify the effects of various process parameters, it is essential to model the process using a numerical method for analyzing and solving the ED-Drilling of PCD process. ANSYS (Computer simulation tool) finite element simulation has been applied to calculate the temperature distribution on the workpiece. The effect of current and pulse on-time in EDDrilling process on heat distribution along the radius and depth of the workpiece has been obtained. In experimental study, it is found that voltage, pulse current and spindle speed have the significant impact on MRR. By increasing these parameters, MRR was improved. Also in numerical simulation, by investigating the effects of pulse current and on-time, the results showed that current is the major influencing parameter in thermal analysis which is in an agreement with experimental result.

Advisor: Kamlakar Rajurkar