Key Engineering Materials Vol. 649

Abstract: The objective of this paper is to construct a CAD model and to determine the optimal geometric features of a 0.1 mm diameter of microdrill. The CAD model was constructed using Pro/Engineer software by determining the flute of a microdrill mathematically. The cross section comparison between the model and fabricated microdrill was carried out by cutting at different lengths, and the results of the web thickness of the model and the fabricated microdrill were approximately the same. Hence, the CAD Modeling of a microdrill based on determining the flute mathematically by considering both setting angle and profile of a grinding wheel was feasible. The optimal geometric features of a microdrill have been determined by carrying out optimization of the stress/displacement analysis using Pro/Mechanica software so that the maximum stress Von Mises of the microdrill was minimal.

Abstract: Optical film is an important component for LCDs, cell phones and other mobile devices. It is crucial to ensure an optical films is defect-free. However, derive from the inherent translucent characteristic, many images of defects of optical films are low contrast. Low-contrast defects are notorious for their difficult to be detected. As some low-contrast defects are barely visible to human being without special training, it is indeed a challenging task to capture low-contrast defect images. To overcome the difficulty, we thoroughly investigated various of imaging and lighting technologies. After images have been captured successfully, we devided the captured defects, based on their sizes, into two categories, i.e. macro defects and micro defects. To detect both large and small defects, we set up a macro inspection system and a micro inspection system, respectively. In the study, we provide an easy to understand approach to reveal low-contrast defects. The experimental results showed that the proposed inspection system and method is capable of detecting low-contrast defects such as uneven coatings, streaks, white spots and foreign particles.

Abstract: This study discussed abrasive machining of aspheric glass lens, with the aim to increase the aspheric lens machining efficiency and reduce the back-end polishing process. The discussions covered "optical lens design", "Taguchi method optimization", "grinding force measurement", and "on-line real-time inspection". A window interface was designed by using Borland C⁺⁺ Builder for optical glass design. The aspheric design parameters were substituted in it to obtain the machining path. In terms of Taguchi method optimization, the performance of electroformed grinding rod was compared with that of resin grinding rod. Taguchi method was used to look for optimization, and the quality characteristic was surface roughness. After experimental analysis, the optimization results were: using a resin binder grinding rod, the optimum parameter of 50,000 (rpm), forward grinding, feeding at 10 mm/min, grinding depth at 0.02mm, and aspheric lens surface roughness of 0.03μm. In terms of grinding force measurement, an eight-ring strain gage dynamometer was designed to measure the optimum grinding force. The measurement result showed that the grinding force in vertical direction was 3.2kg, and that in horizontal direction is 4kg. In terms of visual inspection, a CCD camera was mounted on the machine, which takes the image of workpiece immediately after it is machined. The form was inspected, and the dismounting error was reduced.

Abstract: The Primary Rockwell Hardness Standard System was set up in the Center for Measurement Standards since July 1996 till June 1997. During the period, a compact laser interferometer, HP10737R 3-axis interferometer system was used to measure the effect of pitch and yaw of the Rockwell Hardness standard machine. Considering to increase the performance of hardness measurement, the geometry of the diamond tip has to be determined. In this paper, we will present the results of indenter geometry by μ-CMM (Coordinate Measuring Machine) in CMS.

Abstract: We employed a gold coated glass cover plate to fabricate the dual compact free running fiber laser combs. It had been used for a difference of repetition rates tunable LIDAR (light detection and ranging) system. Our study shows that the ranging precision is 0.4 μm and the non-ambiguity range is 2.1 m with averaging time of 0.4 s for the distance of 1.09 m. The system with 1 kHz-high update rate and the large non-ambiguity range is potentially useful for manufacturing application applied in absolute distance measurement.

Abstract: The purpose of this paper is to study the multiple performance optimizations of printed circuit board (PCB) drilling parameters. The major characteristics indexes for performance selected to evaluate the processes are flank wear area of microdrill and diameter of the PCB through-hole, and the corresponding drilling parameters are spindle speed, infeed, and backfeed rate. Thus, the grey relational analysis based Taguchi method has been employed to determine the optimal combination of drilling parameters. The results of confirmation experiments reveal that the average values of grey relational grade fall within the 95% confidence interval, hence the multiple performance optimizations of PCB drilling parameters using grey relational analysis based Taguchi method is proven to be reliable and effective.

Abstract: This study aims to optimize the small ball-burnishing process parameters in order to simultaneously improve the surface roughness and superficial surface hardness of the STAVAX material. A newly developed load cell embedded double spring mechanism burnishing tool was designed and fabricated. By utilizing the hybrid grey-based Taguchi method with principal component analysis (PCA) and entropy measurement the optimal process condition was the combination of the burnishing force at 10 N, the step-over at 6 μm, the number of passes at 3 times, the grease for lubricant, and the burnishing speed at 500 mm/min. The burnishing force, step-over, and the number of passes were found to have the main effects on the burnished surfaces among the five chosen control factors. The burnished surface of STAVAX material under the optimal condition was improved from R_a 0.85 to R_a 0.079 for average surface roughness, and from 67.3 HR30N to 72.7 HR30N in term of superficial hardness.

Abstract: Polymer materials have been utilized in microfluidic devices because of their properties and competitive cost for single-use devices. However, most microfabrication processes can not produce true three dimensional features in polymers. In this study, a new method with lost-wax casting was proposed to fabricate three dimensional microstructures in polymer-based microchannels. A feasibility study was conducted with epoxy and paraffin wax sacrifice. The microchannel with both-end fixed horizontal rods was produced with precise dimension. This structure is not possible to be fabricated by other replicating methods such as hot embossing or casting. The proposed lost-wax casting process is expected to advance the development of three dimensional polymer-based microchips for both the experimental research in laboratory and the mass production in industry.