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Laser surface texturing and through-mask electrochemical micromachining (TMECMM) are some of the commonly used methods which include multiple steps to achieve micro-textures. However, for large-area applications, it is desirable to have an economical single-step process. In this regard, ECMM is expected to be a promising and economically viable micro-texturing process for micro-manufacturing industries. This paper proposes a novel maskless EC micro-texturing process using tool sinking technique with low voltage and short pulses. Methodology of using edges (∼30 μm each) of printed circuit boards (PCBs) for ECMM of micro-channels and micro-pillars is a unique one. Micro-pillars, micro-dimples and micro-channels are produced through a direct electrochemical cathode sinking process. Analysis of current density and prediction of width and depth of micro-dimples on a flat stainless steel surface are studied through 2D numerical simulation carried out on COMSOL 4.3a. The proposed method implies the use of less toxic electrolyte, low voltage (1-6 V), short pulses (5 to 50 μs) and selective polymer coating on the tool (cathode). A series of experiments of EC sinking for creating various micro-patterns and micro-structures has been carried out on the flat as well as curved metallic surfaces. This paper reports machining of micro-dimples of 200-300 μm diameter, micro-channels of 150-250 μm and square micro-pillars of 300-350 μm. Comparison of the predicted geometrical dimensions of the micro-dimples through the simulation shows reasonable agreement with the experimental results for the given process parameters of ECMM. The paper also reports a brief comparison of laser surface texturing (LSTex) and electrochemical surface texturing (ECSTex). [ABSTRACT FROM AUTHOR]

A micro-structured nickel insert was investigated for polyether ether ketone (PEEK) injection moulding. The micro-features were circular holes 4 μm in diameter and 2 μm deep, with a 2-μm edge-to-edge distance. Six thousand moulding cycles were operated. Half of the insert was coated by approximately 200 nm CrN. PEEK parts produced by the coated side and uncoated side were compared. Coating thickness was measured at intervals of production and employed to characterize the coating wear. Pillar geometry at fixed locations on PEEK parts was studied by scanning electron microscope (SEM). Energy-dispersive X-ray spectroscopy (EDS) was conducted on the PEEK parts in order to study the possible nickel and silver contamination. The results show that the studied coating had a very low wear, and no nickel or silver contamination on PEEK was detected for both parts produced by coated and uncoated sides. Coating improved demoulding by reducing small indentations on pillars. [ABSTRACT FROM AUTHOR]

Micro-hairs are profound elements widely used in nature. A great variety of animals use them as sensors to gather information about their surroundings. To artificially fabricate these kinds of sensors, we present a method to produce micro-hairs made of polydimethylsiloxane (PDMS). We investigated the laser micro-drilling of wax and polycarbonate (PC) substrates with a 193-nm ArF laser to produce molds suitable for casting micro-hairs. Especially PC molds lead to high-quality micro-hairs. Thus, laser ablation of PC was intensively studied. In order to obtain micro-hair arrays, experiments where performed to optimize the casting techniques of PDMS in PC molds. The possibilities and limitations of the investigated method of micro-hair production are presented. [ABSTRACT FROM AUTHOR]