3D printing has been becoming increasingly helpful and economical for the rapid fabrication of microstructures recently. In this study, we have employed a low-cost stereolithography 3D printer to fabricate a polymeric microfluidic device consisting of a flow-focusing droplet generator (orifice size, 210 μm) and periodical arrays of square micro-posts (210 μm x 210 μm) with the height of 420 μm for the sorting of the droplets based on their sizes. Using a photocurable acrylate monomer as the dispersed phase and aqueous polyvinyl alcohol solution as the continuous phase, we observed the formation of primary droplets with an average diameter of 240 μm together with the satellite droplets. Subsequently, the produced main and satellite droplets were continuously separated through the periodical micro-post arrays based on their sizes.

Step emulsification is widely studied to generate uniform droplets because the droplet size is insensitive to flow fluctuations and mainly influenced by the nozzle geometry. Although various step-emulsification devices have been developed, the accumulation of droplets near the nozzle exit has been a common issue. Here, we propose a novel step-emulsification device consisting of parallel nozzle channels crossing a vertical slit. We fabricated parallel nozzle channels of 20-um height in PDMS (dimethylpolysiloxane) by soft lithography. The vertical slit of 500-um width was machined in a stainless-steel block. The dispersed and continuous phases were an acrylate monomer and an aqueous polyvinyl alcohol solution. When the dispersed and continuous phases were infused from two opposed ends of the parallel channels at appropriate flow rates, droplets were pinched-off in the dripping regime at the nozzles facing the vertical slit. The produced droplets flowed out along the slit in time, which could avoid their aggregation and coalescence. The obtained droplets had an average diameter of 78 µm with a coefficient of variation of ~5%.

Step emulsification is widely used for microfluidic droplet generation. In step emulsification, however, the accumulation of droplets near the nozzles can cause their coalescence, deteriorating the monodispersity of the product. Here, we propose a method for inhibiting droplet clustering near the step-emulsification nozzles by arranging deterministic lateral displacement (DLD) microposts. The opening width and the height of the nozzles were 124 um and 14 um, respectively. The diameter, the gaps, and the height of the posts were 52 um, 48 um, and 109 um, respectively. Critical diameter of the post array was 40 um. Corn oil and 2 wt% polyvinyl alcohol (PVA) solution were used as the disperse phase and the continuous phase, respectively. The main droplets having diameters of ~ 53 um and satellite droplets having diameters of ~ 4 um were generated at the edges near the nozzles. Then, the main droplets migrated across the DLD micropillar array with a small angle away from the nozzles, while the satellite droplets flowed along the flow direction.

This study deals with how to develop big data analytics for smart manufacturing. The analytics consists of five integrated systems: big data preparation system, big data exploration system, data visualization system, data analysis system, and knowledge extraction system. The functional requirements of the systems are elucidated. In addition, a JAVA-based system is developed to materialize the proposed analytics. Moreover, the analytics is applied to electrical discharge machining. It is found that the analytics can find out rules to optimize electrical discharge machining. Furthermore, the analytics can be used for other machining operations. Since it is free from big-data inequality, not only large enterprises but also small and medium enterprises can use it to benefit from big data.

In ultra-precision grinding, it is necessary to consider the effect of grinding conditions on form error. However, even if the set value is an ideal value, in reality there will be an error from the ideal grinding conditions due to various reasons. Therefore, the purpose of this research is to construct a system that measures the error of grinding conditions and carry out compensation grinding. In this report, the grinding condition is estimated from the state of the ground surface using a machine learning technique.

We have developed an etching technique of diamond substrates using a Ni mold, which has high-temperature solid solubility limit of carbon. The diamond etching speed was approximately 1 µm/h. High-speed etching of diamond will contribute to the fabrication of diamond heatsink.

Recently, requirement of miniaturization has gradually increased for some devices operating in a vacuum. We have developed a chip-scale Penning vacuum gauge that can measure the ultra-high vacuum pressure inside the cavity of the device cell. In this report, we evaluated discharge currents depending on vacuum pressure of the Penning vacuum gauge with miniature high-efficiency plasma source.

When measuring a geometric profile of workpiece on a machine tool by using a touch-trigger probe, geometric errors of linear axes can be a major measurement uncertainty contributor. The self-calibration schemes, well established for circularity or straightness measurement, cannot be applied to a free-form geometry. This paper proposes a novel self-calibration scheme for on-machine measurement of arbitrary two-dimensional geometry, based on the five-axis machine tool kinematic model. As an experimental verification, a cross-shaped workpiece is measured in accordance with the proposed self-calibration scheme. As a result, the proposed scheme successfully separated the geometric error of the workpiece from the geometric errors of linear and rotary axes.

In the previous paper, we reported that, when Tool Center Point(TCP) control is turned off, high-speed and high-precision 5-axis machining was achieved by commanding CNC programs created by setting the block length based on CNC block processing time. In this paper, even in the case of Tool Center Point(TCP) control, which is often used in 5-axis machining, high-speed, high-precision 5-axis machining can be achieved by commanding CNC programs created by setting the block length based on CNC block processing time. Using the created programs, planes were machined by simultaneously driving X, Y, Z, B and C axes with a ball end mill, the speed and accuracy were measured, and it was confirmed that high-speed and high-precision machining was achieved.

As one of the accuracy evaluation methods for 5-axis machining centers, we have proposed cube machining, in which a cubic surface is divided into nine planes and machined with different tool postures and paths. However, a size of cube machining and tool posture and path are still under investigation and have not been clearly defined. In this study, the size of the cube that can be machined at any tool posture was quantitatively determined as machining area.