This book is intended for the researchers, teachers, students and practitioners in the fields of progressive manufacturing technologies and also for everyone interested in getting more information on the EDM. Provides a comprehensive set of findings from the evaluation of selected quality indicators machined surface tool steel after wire-cut electrical discharge machining with brass wire electrode. Describes the impact of selected technological parameters of EDM on the HAZ depth using mathematical modeling. The aim of this book is also to highlight the importance of assessing the quality of machined surface after WEDM. Own theoretical and knowledge base, as well as the experimental part was carried out in order to enrich new approach to improve of quality machined surface.