In recent years, oil–water separation has been widely researched to reduce the influences of industrial wastewater and offshore oil spills. A filter membrane with special wettability can achieve the separation because of its opposite wettability for water phase and oil phase. In the field of filter membrane with special wettability, porous metal filter membranes have been much investigated because of the associated high efficiency, portability, high plasticity, high thermal stability, and low cost. This article provides an overview of the research progress of the porous metal filter membrane fabrication and discusses the future developments in this field.

17-4PH stainless steel is widely used for applications of critical importance owing to its favorable property profile. However, the great mechanical performance of 17-4PH stainless steel is at the cost of its unsatisfied machinability. Exploring suitable cooling method becomes an effective way to improve its machinability. This study aims to explore the applicability and feasibility of oils-on-water (OoW), which is a hybrid cooling/lubrication technique, compared with minimum quantity lubrication (MQL) in the finishing turning of 17-4PH stainless steel mixed with different cooling media, namely, cryogenic air (CA, −50 °C) and liquid nitrogen (LN, −178 °C). A comprehensive investigation of the cutting temperature, cutting forces, tool wear characterization and surface quality were studied. The result showed that CA or LN mixed with OoW (CAOoW/LNOoW) achieved the lowest flank wear compared with CA or LN mixed with MQL (CAMQL/LNMQL). Besides, CAMQL had the lowest friction force and coefficient of friction, thus resulting in significant surface roughness, which diminished by 38.4% when compared with dry cutting. The greatest anti-abrasion capability was acquired under LNOoW, wherein the addition of water improved the strength and longevity of the lubrication layer. It was found that the anti-adhesion capacity of the cutting tool increased with the decrease in environmental temperature. Even at cryogenic environment, it is still vital to provide cooling and lubrication to the tool–chip interface for further improving cutting performance.

Purpose: Micro-holes are drilled and plated in flexible printed circuit boards (FPCs) for connecting circuits from different layers. More holes, with diameters smaller than 0.3 mm, are required to be drilled in smaller areas with flexible circuits’ miniaturization. The micro-hole quality of micro-drilling is one of the biggest issues of the flexible circuit manufacturers’ production. However, it is not easy to control the quality of micro-holes. The purpose of this study was to conduct research on the tool wear characteristics of FPC drilling process and its influence on micro-hole quality to improve the micro-hole quality of FPC. Design/methodology/approach: The tool-wear characteristics of micro-drills after FPC drilling were observed. The influence of spindle speed, feed rate, number of drilled holes and entry board materials on tool-wear was analyzed. The hole qualities of FPC micro-drilling were measured and observed. The relationship between tool-wear and hole quality was analyzed. Findings: The result showed that the tool-wear characteristics of FPC micro-drilling was similar to the tool-wear characteristics of rigid printed circuit board (RPC) micro-drilling. Abrasive wear occurred on both the main cutting edges and the chisel edges of micro-drills, even though there was no glass fiber reinforcing the cloth inside FPC. Resin adhesion was observed on the chisel edge. The influence of feed and number of drilled holes on tool-wear was significant. Tool-wear significantly influences the hole quality of FPC. Tool-wear will largely decrease the hole position accuracy of FPC micro-holes. Tool-wear will increase the thickness of PI nail heads and the height of exit burrs. Fracture was the main difference between tool wear of FPC and RPC micro-drilling. Resin adhesion of RPC was much more severe than FPC micro-drilling. Increasing the spindle speed properly may improve tool life and hole quality. Originality/value: The technology and manufacturing of FPC has been little investigated. Research on micro-drilling FPC and research data is lacking so far. The micro-hole quality directly affects the reliability of FPC. Thus, improving the micro-hole quality of FPC is very important.