Surface Anomalies In Turning Of Difficult To Cut Materials With High Pressure Coolant Supply

This thesis presents the underlying mechanisms for the occurrence of surface anomalies in turning of difficult-to-cut materials with high-pressure coolant supply. Based on empirical and analytical investigations of each type of surface anomaly, the cause-and-effect relationships between the relevant process parameters and the surface quality were identified, translated into an explanation model and validated in a case study. Finally, an overview of different possibilities for anomaly-free machining with high-pressure coolant supply were discussed.

In the design of turbomachinery components, a significant effort is carried out regarding the optimization of efficiency. The increase in thermal efficiency particularly involves the introduction of high-performance alloys. Such alloys are for example titanium alloys. Sink electrical discharge machining (sink EDM) is a crucial manufacturing process for components due to its independence of machined material strengths; however, new materials require process design. Hence, research to understand and optimize the machining of titanium alloys is of great benefit to the industry in general. A positive tool polarity is generally adopted in sink EDM to maximize material removal relative to tool wear. Sink EDM of α/β titanium alloys as Ti6Al4V is however atypical in that these materials necessitate a negative tool polarity. Adding to the intrigue are gamma titanium aluminides (γ-TiAl), which machine better under the conventional positive polarity. Established explanatory models of sink EDM fail in resolving the removal behavior – a need for fundamental research is given. This thesis focuses on clarifying the phenomena behind this interesting behavior by investigating removal mechanisms over a range of relevant process conditions. The polarity-effect is demonstrated to arise from the polarity-dependent nature and extent of titanium carbide (TiC) formation on the workpiece surface, which significantly affects material removal mechanisms. An explanatory model, deduced from different experimental and numerical approaches, clarifies the influence of polarity to the formation mechanism of a TiC layer. With regard to monitoring of adverse layer formations, the measurement of acoustic emission (AE) is proven an appropriate concept. A correlation of the AE signal to process forces is even established, which may be crucial to determine the deflection of thin electrodes in EDM. Finally, the knowledge acquired is applied and enhanced in comprehensive process design, that also involves the machining of additively manufactured γ-TiAl. The study reveals the beneficial behavior of the fine microstructure relative to the resulting surface integrity. As a result, this thesis delivers a model-based concept for process design with respect to the adequate choice of tool polarity during machining of titanium alloys.

The Springer Reference Work Handbook of Manufacturing Engineering and Technology provides overviews and in-depth and authoritative analyses on the basic and cutting-edge manufacturing technologies and sciences across a broad spectrum of areas. These topics are commonly encountered in industries as well as in academia. Manufacturing engineering curricula across universities are now essential topics covered in major universities worldwide.

This book focus on the challenges faced by cutting materials with superior mechanical and chemical characteristics, such as hardened steels, titanium alloys, super alloys, ceramics and metal matrix composites. Aspects such as costs and appropriate machining strategy are mentioned. The authors present the characteristics of the materials difficult to cut and comment on appropriate cutting tools for their machining. This book also serves as a reference tool for manufacturers working in industry.

This book provides an overview on current sustainable machining. Its chapters cover the concept in economic, social and environmental dimensions. It provides the reader with proper ways to handle several pollutants produced during the machining process. The book is useful on both undergraduate and postgraduate levels and it is of interest to all those working with manufacturing and machining technology.

A Complete Reference Covering the Latest Technology in Metal Cutting Tools, Processes, and Equipment Metal Cutting Theory and Practice, Third Edition shapes the future of material removal in new and lasting ways. Centered on metallic work materials and traditional chip-forming cutting methods, the book provides a physical understanding of conventional and high-speed machining processes applied to metallic work pieces, and serves as a basis for effective process design and troubleshooting. This latest edition of a well-known reference highlights recent developments, covers the latest research results, and reflects current areas of emphasis in industrial practice. Based on the authors’ extensive automotive production experience, it covers several structural changes, and includes an extensive review of computer aided engineering (CAE) methods for process analysis and design. Providing updated material throughout, it offers insight and understanding to engineers looking to design, operate, troubleshoot, and improve high quality, cost effective metal cutting operations. The book contains extensive up-to-date references to both scientific and trade literature, and provides a description of error mapping and compensation strategies for CNC machines based on recently issued international standards, and includes chapters on cutting fluids and gear machining. The authors also offer updated information on tooling grades and practices for machining compacted graphite iron, nickel alloys, and other hard-to-machine materials, as well as a full description of minimum quantity lubrication systems, tooling, and processing practices. In addition, updated topics include machine tool types and structures, cutting tool materials and coatings, cutting mechanics and temperatures, process simulation and analysis, and tool wear from both chemical and mechanical viewpoints. Comprised of 17 chapters, this detailed study: Describes the common machining operations used to produce specific shapes or surface characteristics Contains conventional and advanced cutting tool technologies Explains the properties and characteristics of tools which influence tool design or selection Clarifies the physical mechanisms which lead to tool failure and identifies general strategies for reducing failure rates and increasing tool life Includes common machinability criteria, tests, and indices Breaks down the economics of machining operations Offers an overview of the engineering aspects of MQL machining Summarizes gear machining and finishing methods for common gear types, and more Metal Cutting Theory and Practice, Third Edition emphasizes the physical understanding and analysis for robust process design, troubleshooting, and improvement, and aids manufacturing engineering professionals, and engineering students in manufacturing engineering and machining processes programs.