Nonconventional Technologies Review – no. 2/2010 24 RELATIONSHIP DIAGRAM AND TREE DIAGRAM APPLIED AT INCREASING FLEXIBILITY OF ULTRASONIC ELECTRODISCHARGE MACHINING TECHNOLOGY Niculae-Ion MARINESCU 1 , Daniel GHICULESCU 2 , Daniela GHICULESCU 3 , RICHARD GONCZI 4 1 “Politehnica” University of Bucharest, niculae.marinescu@nsn.pub.ro 2 “Politehnica” University of Bucharest, daniel.ghiculescu@nsn.pub.ro 3 National Authority for Scientific Research, daniela.ghiculescu@ancs.ro 4 Hungarian Science and Technology Foundation, richard.gonczi@tetalap.hu Abstract: The paper deals with improving the performances of ultrasonic aided EDM micromachining (EDM+US) through using some quality management instruments like relationship diagram and tree diagram. Some characteristics of these instruments are presented and opportunities to combine them in order to solve the same problem aiming at improving the obtained results by synergy. The mix application of these instruments is achieved in order to increase the flexibility of EDM+US through identification and removing the causes of this main disadvantage of this combined nonconventional technology. Keywords: electrodischarge machining, ultrasonics, flexibility, quality improvement methods. 1. INTRODUCTION The quality management instruments as Relationship Diagram and Tree Diagram are considered new instruments able to solve problems belonging to management system but they are also applicable to operational management due to their versatility [1]. In this case, a problem or process improvement is addressed, i.e. the flexibility of electrodischarge machining aided by longitudinal vibrations of electrode-tool in micromachining mode (EDM+US). The EDM micromachining process is characterized by very narrow working gap, which frequently causes short-circuits and therefore instability of material removal process, which affects the output technological parameters: surface quality, precision and machining rate [2]. Ultrasonic assistance of microEDM is capable to improve these technological performances. Only one main disadvantage remains to be solved: the time consume during manufacture preparation, which makes EDM+US low efficient at individual and short series production. Practice of quality management confirms that more complementary methods / instruments - as it is the case of the mentioned instruments - are used to solve the same problem, more the results are better, based on their synergy. 2. RELATIONSHIP DIAGRAM METHODOLOGY The relationship diagram also called interrelationship diagram or network diagram shows cause-and-effect relationships between issues. This quality management instrument helps the work team to understand the natural links between different aspects of a complex group of factors that affects the solving of a problem. Some recommendations for relationship diagram application are [3]: ● When trying to understand the links between cause-and-effect relationships, in order to identify the most important factors of quality improvement; ● When the problem to deal with consists in a great complex of elements and it is analyzed for causes identification; ● When a complex solution, device or process is being implemented; this is the case of EDM+US flexibility improvement; ● After application of an affinity diagram, cause-and-effect diagram, if the work team wants to explore more the relations between ideas. The methodology of relationship diagram application comprises the following steps: Step 1. A statement defining the problem that the relationship diagram will try to solve is written on a card or post-it and place it at the top of the work surface (chart pack, panel