ZrO₂ ceramics are currently used in a broad range of industrial applications. However, the machining of post-sintered ZrO₂ ceramic is a difficult task, due to its high hardness and brittleness. In this study, micro-milling of ZrO₂ with two kinds of diamond-coated end mills has been conducted on a Kern MMP 2522 micro-milling center (Kern Microtechnik GmbH, Eschenlohe, Germany). To achieve a ductile mode machining of ZrO₂, the feed per tooth and depth of cut was set in the range of a few micrometers. Cutting force and machined surface roughness have been measured by a Kistler MiniDynamometer (Kistler Group, Winterthur, Switzerland) and a Talysurf 120 L profilometer (Taylor Hobson Ltd., Leicester, UK), respectively. Machined surface topography and tool wear have been examined under SEM. Experiment results show that the material can be removed in ductile mode, and mirror quality surface with Ra low as 0.02 μm can be achieved. Curled and smooth chips have been collected and observed. The axial cutting force F_z is always bigger than F_x and F_y, and presents a rising trend with increasing of milling length. Tool wear includes delamination of diamond coating and wear of tungsten carbide substrate. Without the protection of diamond coating, the tungsten carbide substrate was worn out quickly, resulting a change of tool tip geometry.

The setting of cutting variables for precision milling of ceramics is important to both the machined surface quality and material removal rate (MRR). This work specifically aims at the performance of corner radius PCD (polycrystalline diamond) end mill in precision milling of zirconia ceramics with relatively big cutting parameters. The characteristics of the cutting zone in precision milling ceramics with corner radius end mill are analyzed. The relationships between the maximum uncut chip thickness (h_max) and the milling parameters including feed per tooth (f_z), axial depth of cut (a_p) and tool corner radius (r_ε) are discussed. Precision milling experiments with exploratory milling parameters that cause uncut chip thickness larger than the critical value were carried out. The material removal mechanism was also analyzed. According to the results, it is advisable to increase f_z appropriately during precision milling ZrO₂ ceramics with corner radius end mill. There is still a chance to obtain ductile processed surface, as long as the brittle failure area is controlled within a certain range. The appropriate increasing of a_p, not only can prevent the brittle damage from affecting the machined surface, but also could increase the MRR. The milling force increases with increasing MRR, but the surface roughness can still be stabilized within a certain range.

Globalization of the micro manufacturing technology has become a trend. This technology has been widely used in many fields, especially in aerospace field and biological medicine. The electrolytic PVC mask of micro-hole array is difficult to machine because of the high positional accuracy of the micro-hole array, small diameter of the holes and the high requirement of machining quality. This paper studied the influence of workpiece property, optimization of machining parameters, and chips removing in machining of the electrolytic PVC mask using micromechanical drilling. A feasible method with high efficiency is presented.

Although the current power grid enterprises have established emergency plans for a variety of disasters and large-scale blackouts, the number of emergency plans is huge. Each process strongly relies on experienced decision-making. The intelligentization of emergency plan execution needs to be improved. This paper studies the automatic reasoning response method in the process of emergency plan implementation and disposal. Furthermore it proposes a construction method of knowledge database and knowledge graph of power grid emergency plan, as well as the pattern matching method and relationship matching model of power grid emergency plan reasoning. Reasoning and application of some main responsibilities in typical disaster response are discussed. The research results provide theoretical support for the improvement of the implementation efficiency of each process of the power grid emergency plan.