Microinjection molding (µIM) appears to be one of the most efficient processes for the large-scale production of thermoplastic polymer microparts. The microinjection molding process is not just a scaling down of the conventional injection process; it requires a rethinking of each part of the process. This review proposes a comparative description of each step of the microinjection molding process (µIM) with conventional injection molding (IM). Micromolding machines have been developed since the 1990s and a comparison between the existing ones is made. The techniques used for the realization of mold inserts are presented, such as lithography process (LIGA), laser micromachining and micro electrical discharge machining (µEDM). Regarding the molding step, the variotherm equipment used for the temperature variation is presented and the problems to solve for each molding phase are listed. Throughout this review, the differences existing between µIM and conventional molding are highlighted.

https://iopscience.iop.org/article/10.1088/0960-1317/17/6/R02/pdf

Microinjection molding of thermoplastic polymers: a review

Calcium orthophosphate deposits: Preparation, properties and biomedical applications.

Multi-objective optimization using Taguchi based grey relational analysis for micro-milling of Al 7075 material with ball nose end mill

Quality and productivity methods for evaluating quality parameter design methods for specifying tolerance quality management for production processes

Taguchi on robust technology development : bringing quality engineering upstream

Micro hot embossing of thermoplastic polymers is a promising process to fabricate high precision and high quality features in micro/nano scale. This technology has experienced more than 40 years development and has been partially applied in industrial production. Three modes of micro hot embossing including plate-to-plate, roll-to-plate and roll-to-roll have been successively developed to meet the increasing demand for large-area patterned polymeric films. This review surveys recent progress of micro hot embossing in terms of polymeric material behavior, embossing process and corresponding apparatus. Besides, challenges and innovations in mold fabrication techniques are comprehensively summarized and industrial applications are systematically cataloged as well. Finally, technical challenges and future trends are presented for micro hot embossing of thermoplastic polymers.

https://iopscience.iop.org/article/10.1088/0960-1317/24/1/013001/pdf

Micro hot embossing of thermoplastic polymers: a review

This paper reviews the applications of focused ion beam (FIB) sputtering for micro/nano fabrication. Basic principles of FIB were briefly discussed, and then empirical and fundamental models for sputtering yield, material removal rate, and surface roughness were presented and compared. The empirical models were more useful for application compared to fundamental models. Fabrication of various micro and nano structures was discussed. Trimmed atomic force microscope (AFM) tips were tested in measurement and imaging of high aspect ratio nanopillars where higher accuracy and clarity were observed. Micromilling tool fabricated using FIB sputtering was used to machine microchannels. Slicing and dwell time control approaches on FIB sputtering were presented for the fabrication of three dimensional microcavities. The first approach is preferred for practical applications. The maximum aspect ratio of 13:1 of the microstructures was achieved. The minimum size of the nanopore was in the range of 2–10 μm. Cavities of microgear of 70 μm outside diameter were sputtered with submicrometer accuracy and 2–5 nm average surface roughness. The microcavities were then filled with polymer in a subsequent micromodling process. The replicated microcomponents were inspected with scanning electron microscope where faithful duplication of accuracy and surface texture of the cavity was observed.

A review of focused ion beam sputtering

Investigation of material removal characteristics in EDM of nonconductive ZrO2 ceramic

This article discusses the investigation and optimization of the process parameters of conventional wire electrical discharge machining (WEDM) of a copper substrate for microfabrication. The effect of discharge current, pulse-on time, and gap voltage on surface finish were studied. The average surface roughness (R a ) and peak-to-valley height (R t ) were measured with a surface profiler. The surface roughness increased with higher discharge current and gap voltage. With the increase of pulse-on time, the surface roughness decreased. Statistical models were established to predict the surface roughness R a and R t in terms of discharge current, pulse-on time, and gap voltage. Using the optimized parameters, miniaturized spur gears, and plate-shaped hot embossing microtools were fabricated where an average surface roughness of about 1 µ m and dimensional accuracy of 1–2% were achieved.

Experimental Study of Conventional Wire Electrical Discharge Machining for Microfabrication

Electro discharge machining (EDM) process is a non-conventional and non-contact machining operation which is used in industry for high precision products. EDM is known for machining hard and brittle conductivematerials since it can melt any electrically conductive material regardless of its hardness. The workpiece machined by EDM depends on thermal conductivity, electrical resistivity, and melting points of the materials. The tool and the workpiece are adequately both immersed in a dielectric medium, such as, kerosene, deionised water or any other suitable fluid. This paper is reviewed comprehensively on types of EDM operation. A brief discussion is also done on the machining responses and mathematical modelling.

/pdf/electrical-discharge-machining-edm-a-review-8sxoj3y7j2.pdf

Electrical Discharge Machining (EDM): A Review

This paper discusses the comparison of micro machining process using conventional and micro wire electrical discharge machining (WEDM) for fabrication of miniaturized components. Seventeen toothed miniaturized spur gear of 3.5 and 1.2 mm outside diameter were fabricated by conventional and micro WEDM respectively. The process parameters for both conventional and micro WEDM were optimized by preliminary experiments and analysis. The gears were investigated for the quality of surface finish and dimensional accuracy which were used as the criteria for the process evaluation. An average surface roughness (Ra) of 50 nm and dimensional accuracy of 0.1–1 µm were achieved in micro WEDM. Whenever applied conventional WEDM for meso/micro fabrication, a Ra surface roughness of 1.8 µm and dimensional accuracy of 2–3 µm were achieved. However, this level of surface roughness and dimensional accuracy are acceptable in many applications of micro engineering. A window of conventional WEDM consisting of low energy discharge parameters is identified for micromachining.

Mohammad Yeakub Ali

Papers

A review of focused ion beam sputtering

Investigation of material removal characteristics in EDM of nonconductive ZrO2 ceramic

Experimental Study of Conventional Wire Electrical Discharge Machining for Microfabrication

Electrical Discharge Machining (EDM): A Review

Comparative study of conventional and micro WEDM based on machining of meso/micro Sized Spur Gear