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Micro-EDM
Published in V. K. Jain, Advanced Machining Science, 2023
Over the last few decades, the technology boom has been linked to the miniaturization of instruments, parts, and machines due to the advances in micromanufacturing techniques. Microfabrication techniques have a huge demand in the biotechnology, automotive, communication, electronics, and avionics industries. Micromachining techniques – both traditional and non-traditional – are widely used to meet these requirements and to produce miniature products. Microfabrication using conventional machining processes is limited due to tool size, material and various forms of wear, and heat generation owing to the friction force between the tool and workpiece during machining [1]. Non-traditional (also called advanced, unconventional, or new) micromachining processes are suggested to overcome these problems where no contact between the microtool and workpiece is involved. Among various advanced micromachining technologies, micro electro discharge machining (μ-EDM/micro-EDM) is one of the economic thermoelectric type micromachining processes capable of machining conductive materials regardless of the workpiece's mechanical properties as hardness and strength, adding to facilitate the fabrication of complex microfeatures on hard materials. Microcomponent inaccuracy, on account of vibration, chatter, mechanical stress, deformation of tool electrode, etc., is absent in EDM due to the lack of physical contact between the tool and workpiece [2].
Therapeutic Strategies and Future Research
Published in Mark A. Mentzer, Mild Traumatic Brain Injury, 2020
MEMS is the integration of mechanical elements, sensors, actuators, and electronics on a common silicon substrate through microfabrication technology. While the electronics are fabricated using integrated circuit (IC) process sequences (e.g., CMOS, Bipolar, or BICMOS), the micromechanical components are fabricated using compatible “micromachining” processes that selectively etch away parts of the silicon wafer or add new structural layers to form mechanical and electromechanical devices (see Figure 5.1).
Glossary of scientific and technical terms in bioengineering and biological engineering
Published in Megh R. Goyal, Scientific and Technical Terms in Bioengineering and Biological Engineering, 2018
Microfabrication includes techniques used to manufacture integrated circuits (ICs), discrete microelectronic devices, MEMS devices such as sensors and actuators, and various electro-optic devices. University of Louisville Microfabrication Lab is currently serving as a center for research activity in the areas of micromachined sensors and actuators, electrooptic devices, special-purpose microelectronic devices, planar waveguides, chemical transducers, microstrip and microgap radiation detectors, micromachined nozzles, and micromachined inkjet printheads.
Micro metal powder hot embossing: influence of binder on austenitic stainless steel microparts replicability
Published in Powder Metallurgy, 2022
E. W. Sequeiros, M. T. Vieira, M. F. Vieira
Microfabrication technologies are emerging due to the increasing demand in microengineering applications, such as micromoulds, micromechanical structures, sensors, and micromedical devices. They are considered promising technologies for today and the near future, but they still have challenges to overcome [1,2]. Micro hot embossing and micro-polymer injection moulding are replicative technologies well established for the mass production of low-cost polymer microparts or devices [1,2]. However, there are specifications that polymers do not accomplish, such as mechanical properties and thermal stability. Micro metal injection moulding (microMIM) has been developed to overcome polymer limitations [3,4]. Metal micro powder hot embossing is a recent sustainable process based on MIM that can provide complex geometries for small metallic parts at low cost and without waste [5,6]. In general, hot embossing is a replicative process that provides microparts and in which shaping occurs by applying heat and pressure for predefined times [1]. In the last decade, the optimisation of this new replicative process for metallic powder remains an objective of the research. Several scientific studies address the control of the main factors determining the quality of hot embossing parts, such as shaping process parameters (temperature, pressure, and time), rheological properties, and die surface finishing [7–14]. Hot embossing and micro hot embossing techniques can be carried out in the laboratory using a relatively unsophisticated hot press [15].
Fabrication and Thermal Characterization of Composite Cu-CNT Micropillars for Capillary-driven Phase-Change Cooling Devices
Published in Nanoscale and Microscale Thermophysical Engineering, 2019
G. Rojo, S. Ghanbari, J. Darabi
In this work, composite Cu-CNT micropillars were fabricated on a copper substrate as a wick structure for potential use in capillary-driven heat pipes and vapor chambers. Copper has excellent thermal and electrical conductivities and is commonly used as a heat spreader in electronic cooling applications. However, copper has a high coefficient of thermal expansion (CTE) and its corrosion resistance is relatively poor. On the other hand, CNTs possess a low coefficient of thermal expansion, a very high thermal conductivity, and a high corrosion resistance [22]. Thus, the reliability of electronic devices can be improved if materials with low coefficient of thermal expansion, high thermal conductivity, and better corrosion resistance such as composite Cu-CNT structures are used. Figure 2 illustrates a simplified process flow to fabricate composite Cu-CNT mushroom-like micropillars. One of the crucial steps in the fabrication of a micropillar array is making a template. The photolithography process is the standard technique for pattern transfer in microfabrication. However, this method is very expensive and requires cleanroom environment and sophisticated equipment. In this study, a polystyrene mesh net with an opening size of 50 µm and a thickness of 112 µm was used as a micropillar array template. While these dimensions may not be the optimum geometry, this was the smallest mesh net that was commercially available. This method was found to be a very rapid and inexpensive way to make the micropillar pattern and was suitable to demonstrate the proof of concept. First, a copper substrate was polished using waterproof sandpapers with grit sizes of 600, 800 and 1000. Next, the polyester mesh template was bonded to the polished copper plate by applying heat and pressure. The template was sandwiched between the polished substrate and a backing plate of a similar size, and a uniform pressure was then applied on the template using a clamp. To prevent bonding of the template to the backing plate, a plastic sheet was placed between them. The entire fixture was placed in an oven for 1 hour at 140°C. After heat treatment, the specimen was removed from the oven and allowed to cool at room temperature. The clamp and the backing copper plate were then removed.
Experimental and numerical investigation of cutting forces in micro-milling of polycarbonate glass
Published in Machining Science and Technology, 2020
Muhammad Pervej Jahan, Jianfeng Ma, Craig Hanson, Xingbang Chen, Greg K. Arbuckle
In recent years, polycarbonates (PC) have been extensively used for optical lenses, and specially for cases where impact resistance is the most important requirements, such as safety glasses, bullet-proof glass and so on. Polycarbonates have found important applications in electronic, automotive, aerospace, construction, data storage, microfluidic discs and DNA detection devices (Rogers, 2015). Most of the applications of polycarbonates requires very high quality surface finish of the part to be used. In the application of microfluidic discs and DNA detection devices, high quality micro-channels are needed with smooth surface finish to ensure uninterrupted flow of drug or any other bio fluid used (Liu et al., 2001; Guckenberger et al., 2015). The laser based photolithography, and chemical etching based microfabrication processes are being used by the researchers over the decade to fabricate microfeatures on polymeric substances and glasses (Perveen et al., 2012). There have been many studies on the application of various laser sources for machining and ablation on the PC (Mutapcic et al. 2004; Zheng et al. 2006; Karazi and Brabazon, 2011; Gruescu et al. 2012; Rey-García et al. 2012; Chen and Hu, 2017). Although the laser and photolithography based microfabrication processes provides micro-features with high dimensional accuracy, the fabrication processes are very slow and costly, as well as involve various hazardous chemicals. For most of the cases, those processes are not suitable for mass fabrication of micro features and components, and are also limited to material types. Among other non-conventional machining of PC, abrasive water jet machining (AWJM) was found to be suitable for machining polycarbonates. There have been several research studies on investigating the feasibility of machining PC using AWJM (Mohaupt and Burns, 1974; Guo and Ramulu, 2001; Getu et al. 2008). Although AWJM can machine glass and polymeric materials without heat affected surface and yield minimal changes in the microstructures, it has limitations to miniaturization. The size of the micro-channels or micro features is limited by nozzle size of AWJM, which must be bigger than the abrasive particle size. There have been few research studies on other innovative non-conventional finishing and polishing processes, such as chemically assisted ultrasonic machining (USM) (Singh et al. 2017) and magnetic assisted polishing (Lee et al. 2013) for successfully machining polycarbonates. However, those finishing processes are mostly suited as post processing techniques, because of lower material removal rate compared to traditional machining processes.