12 th International Research/Expert Conference ”Trends in the Development of Machinery and Associated Technology” TMT 2008, Istanbul, Turkey, 26-30 August, 2008 ENVIRONMENT-FRIENDLY CUTTING OF CYLINDRICAL GEARS Domnita F. Fratila Csaba Gyenge Olimpia R. Ros Technical University of Cluj-Napoca 400641 Cluj-Napoca, Bd. Muncii 103-105 Romania ABSTRACT One of the main sources of environmental pollution during the machining processes is the huge amount of supplied cutting fluids. To avoid the problems caused by use of cutting fluids, considerable progress has been made in the last years in the field of near–dry machining. The conversion from conventional lubrication- cooling processes to minimal quantity lubrication methods demands new tasks classification in the tribological system in order to guarantee the process safety and product quality. In the paper the authors presents their theoretical and practical researches in the field of cylindrical gear milling using several kinds tools, lubrication and cooling methods, in order to evaluate the effects of some environment-friendly techniques. Keywords: Near-dry cutting, gear milling, environment-friendly processes 1. INTRODUCTION TO NEAR DRY CUTTING 1.1. Near dry cutting as a part of green manufacturing During actual period an advanced manufacturing mode – Green Manufacturing (GM) - is critically required for sustainable development process. In this sense modern machining processes face continuous cost pressures and high quality expectations. During the machining processes the cutting fluid is one of the main sources of environmental pollution. How to minimize the environmental impact of manufacturing systems related to cutting fluids is one of the important issues in the field of GM. Different types of cutting fluids employed in the manufacturing process have different impacts on the environment. The three objectives of quality, cost, and environmental impact are the critical factors, which should be integrated into cutting fluids selection for GM [2]. Machining technologies have been continuously developed aiming at getting the higher productivity and precision in manufacturing processes. Cutting fluids have been widely used to achieve these purposes, their action of cooling and lubrication, and to play a significant role in successful machining operations. Concerning the environmental issues, such ozone layer depletion, the global warming effects, and environmental pollution, it has nowadays raised the importance of environmentally friendly manufacturing. To avoid the above mentioned problems, caused by cutting fluids, considerable progress has been made in the last years in the field of dry and near-dry machining (NDM). In particular, machining with minimal quantity lubrication (MQL) has been accepted as a representative near-dry application because of its environmentally friendly characteristics. 1.2. Technical features of MQL and NDM in the practice The large number of studies has demonstrated that it can prove the satisfactory outcome in many practical machining operations (Fig. 1). Concerning the cutting lubricants properties for MQL they should be selected not only on the basis of its primary characteristics (cutting performance) but also by reason of its secondary characteristics, such as biodegradability, oxidation stability, storage stability, and water-soil-air pollution. Although the tribological action of a very small amount of lubricant is certainly of 17