Development and analysis of all-ceramic micro end mills with diameters ≤ 50 µm

与其他微加工方法相比，微铣削具有显著的优势。这些优点是可加工材料的范围大，可实现的几何复杂性以及高表面质量。今天，直径≤50µm的立铣刀几乎完全由硬质合金制成，因为它具有良好的材料性能和可加工性。然而，低刀具直径的硬质合金刀具导致刀具稳定性下降，而比切削力不成比例地增加。此外，由于切削刃半径的影响越来越大，出现了所谓的犁头效应，这意味着工件材料被压在切削刃下方并被推过而不被切割。除了表面质量的恶化和毛刺的增加外，犁耕效应还导致加工力的增加和细丝微刀具的强烈磨损。由于所用硬质合金的微观组织和晶粒尺寸，刀具的最小切削刃半径受到超细晶硬质合金晶粒尺寸（0.2µm）的限制。由于陶瓷的微观结构，使用陶瓷作为切削材料可以进一步减小刀具可实现的切削刃半径，从而减小加工力。此外，陶瓷具有比硬质合金更高的热硬度和耐磨性，但目前尚未应用于刀具直径≤50 μm的铣刀。该研究项目的总体目标是首次开发和应用直径≤50 μm的全陶瓷微铣刀。与宏观刀具类似，新型陶瓷立铣刀有望减少刀具磨损。此外，提高了工件的表面质量，减少了毛刺的形成，提高了刀具的寿命。为此，选择了合适的切削陶瓷，并进行了磨损研究的类比试验。在此基础上，通过数值仿真和运动学仿真，确定了全陶瓷立铣刀的刀具几何形状。采用磨削加工的微立铣刀进行铣削试验。结果与本实验室现有硬质合金立铣刀的铣削结果进行了比较。

Micro milling offers significant advantages compared to other micro machining methods. These advantages are the high range of machinable materials, the achievable geometric complexity as well as the high surface quality. Today, end mills with diameters ≤ 50 µm are almost exclusively made of cemented carbide, due to its good material properties and machinability.However, the low tool diameters of the cemented carbide tools lead to a reduction of tool stability, while the specific cutting forces increase disproportionately. Furthermore, due to the increasing influence of the cutting edge radius, the so-called ploughing-effect occurs, which means that the workpiece material is pressed underneath the cutting edge and pushed through without being cut. In addition to a deterioration of the surface quality and increasing burr formation, the ploughing-effect leads to increased process forces and a strong wear of the filigree micro tool. Due to the microstructure and the grain size of the cemented carbides used, the minimum cutting edge radii of the tools is limited by the grain size of ultra-fine-grained carbides (0.2 µm).Caused by their microstructure, using ceramics as cutting material can further reduce the achievable cutting edge radii of the tools and thus the occurring process forces. In addition, ceramics have a higher hot hardness and wear resistance than cemented carbides, but are currently not applied for milling tools with tool diameters ≤ 50 μm.The overall goal of the research project is the first-time development and application of fully ceramic micro milling tools with diameters ≤ 50 μm. In analogy to macro cutting tools, the novel ceramic end mills are expected to reduce tool wear. In addition, improved surface quality of the workpieces, reduced burr formation and a higher tool life are expected. For this purpose, suitable cutting ceramics are selected and analogy tests for wear investigations are carried out. On this basis, the tool geometry of the fully ceramic end mills is developed by numerical and kinematic simulation. The micro end mills produced via grinding are used for milling tests. The results are compared with milling results of existing cemented carbide end mills produced in the proposer’s lab.