Date of Award
Doctor of Philosophy
Mechanical and Aerospace Engineering
Dr. John A. Pattern
Dr. Muralidhar Ghantasala
Dr. Daniel Kujawski
Dr. Mitchel Keil
laser augmented diamond drilling (LADD), micro laser assisted machining, laser, diamond, hard and brittle materials, machining
New technologies demand new materials with better mechanical, optical, and thermal properties. Materials that are light weight, strong with high resistance to high temperatures, and compatible with a predetermined condition. Such materials usually are challenging to manufacture and process compared to widely available materials such as metals. Ceramics and semiconductors are considered extremely hard and brittle, making them very difficult to cut and manufacture. The other major and fast-growing type of materials are composites (including Ceramic Matrix Composites, CMC) that are also considered very challenging to machine. All these materials have many applications in major industries (i.e. electronics, aerospace, optics, automotive, etc.) due to their superior properties, such as those indicated above. To make a final product from raw material in most cases at least one or a combination of machining processes, such as cutting, turning, milling, and drilling is necessary. Machining, or turning, of hard and brittle materials such as ceramics and semiconductors, has been a challenge for many years. Achieving good surface finish, avoiding surface and subsurface damages, and achieving a high material removal rate are extremely challenging for these materials. High tool wear is one of the main drawbacks of machining these types of materials. It not only increases the cost of the tooling but also increases the total cost of a finished workpiece because of the downtime of the process. Mechanical drilling of hard, brittle and challenging materials as a major material removal process poses many problems as well. Rapid tool wear and damage to materials are common obstacles. Developing new techniques to overcome the obstacles in machining new materials is necessary to keep up with the invention of them. Hybrid processes that combine at least two methods of material removal (or material processing) are a possible solution for these challenges. A combination of a mechanical material removal process with a heat source such as laser to get benefit both of these techniques can help overcome these obstacles. Two novel techniques of mechanical-thermal methods are investigated in this dissertation. One of them, Micro Laser Assisted Machining (μ-LAM) which is a process used for turning the hard and brittle materials and is investigated in Part A of this dissertation. The μ-LAM has been under development over the past decade. However, to be able to use it in the actual machining world and in the industry environment, it needs to be improved and optimized. The chapters in part A of this dissertation are mainly focused on the investigation of different aspects and optimization of parameters of the μ-LAM technique. In part B, a novel technique for drilling challenging materials, Laser Augmented Diamond Drilling (LADD), is introduced and studied. In the LADD mechanical drilling combined with a heat source such as laser to get benefit from both to increase the productivity by improving the quality, precision, and tool life. Two different types of materials were drilled with the aid of this technique, and results were analyzed. Cutting forces were particularly evaluated and the quality achieved is discussed in the chapters of part B.
Mohammadi, Hossein, "Hybrid Processes in Material Removal of Hard and Brittle Materials" (2018). Dissertations. 3363.