PVD-coating of electroplated cBN grinding tools to optimize the wear and application behavior when grinding nickel-based alloys

本课题旨在通过涂层磨削镍基合金时，减少砂轮磨损，提高材料的去除率。由于其优异的高温强度、高疲劳强度和优异的耐腐蚀性，镍基合金被用于高科技领域，如涡轮机和发动机。所需的低粗糙度表面通常只能通过磨削来制造。由于镍基合金的热、机械和化学性能，磨削镍基合金是困难的。砂轮磨损的减少以及高质量表面和近表面完整性的产生是挑战。在加工过程中，砂轮与工件之间的摩擦导致机械磨损，摩擦产生的热量加速了化学磨损和热磨损。在砂轮上涂覆涂层是应对上述挑战的一种很有前途的方法。通过使用涂层，摩擦将减少，颗粒保持力将增加，从而可能通过减少电偶结合厚度来获得更大的芯片空间。仍然缺乏对涂层工艺参数和工艺结果之间的相互依赖关系的了解。在项目结束时，用PVD涂层磨削镍基合金时，将实现减少刀具磨损和摩擦、增加切屑空间和优化磨屑去除速率的目的。将开发一种PVD涂层，以增加磨粒夹持力，并改善砂轮的摩擦学和非粘附性。由于施加的PVD涂层的电化学键性能得到改善，降低了CBN颗粒的键合水平，芯片空间将最大化。我们将考察不同PVD涂层和粘结层的颗粒保持力。在镍基合金的高效深进给磨削中，通过调整切屑间距的涂层CBN砂轮与具有标准切屑间距的非涂层CBN砂轮的实验比较，验证了PVD涂层的优势。该项目的结果将是一个涂层砂轮，具有调整的芯片空间和更大的空间，以冷却润滑剂和正在加工的芯片。结果表明，在不造成近表层热损伤的情况下，提高了镍基合金高效深进给磨削时的材料去除率和总材料去除量。砂轮的性能和加工效率将得到提高。

This project aims to decrease the grinding wheel wear and to increase the material removal rate when grinding nickel-based alloys by applying coatings. Due to their excellent high-temperature strength, high fatigue strength, and exceptional corrosion resistance, nickel-based alloys are used in high-tech areas such as in turbines and engines. The required surfaces with low roughness can often only be manufactured by grinding. Grinding nickel-based alloys is difficult because of their thermal, mechanical and chemical properties. The reduction of the grinding wheel wear as well as the generation of a high quality surface and near surface integrity are the challenges. The friction between grinding wheel and workpiece during the process leads to mechanical wear and the heat from friction accelerates the chemical and thermal wear. The application of coatings on grinding wheels is a promising method to meet the mentioned challenges. By using coatings, the friction will be reduced and the grain retention force will be increased, whereby a bigger chip space is possible via reduction of the galvanic bond thickness. There is still a lack in understanding the interdependencies between the coating process parameters and the process results. At the end of the project, a reduction of tool wear and friction as well as an increase of the chip space and the involved optimization of the martial removal rate when grinding nickel based alloys with PVD-coatings will be achieved. A PVD-coating will be developed that increases the grain holding forces and improves the tribological and non-adhesive properties of the grinding wheel. The chip space will be maximized by a reduced bond level of the cBN grains because of the improved galvanic bond properties of the applied PVD-coating. The grain retention forces applying different PVD-coatings and bond levels will be examined. The advantage of the PVD-coating will be validated in an experimental comparison of coated cBN-grinding wheels with adjusted chip space against non-coated cBN-grinding wheels with standard chip space at high efficiency deep feed grinding of nickel based alloys. The project result will be a coated grinding wheel with adjusted chip space and larger space for cooling lubricant and chips in process. As a consequence, the material removal rate and the total material removal when high efficiency deep feed grinding nickel-based alloys will be increased without thermal damage of the near surface layer. The grinding wheels’ performance and the efficiency of the process will be increased.