Key Engineering Materials Vol. 1012

Abstract: This action research aims to reduce the setup time of a wire coating extruder machine. The case company performed about 6 setups per day, with an average setup time of 58.67 minutes per setup, resulting in a total setup time of approximately 352.02 minutes per day. The Single Minute Exchange of Dies (SMED) technique, based on the principles of Shigeo Shingo, was applied. The machine setup was divided into 7 stages to suit the needs of the case study company. After the improvements, the setup time was reduced to 31.97 minutes per setup, resulting in a 45.51% increase in machine operation efficiency. The tools and techniques used in this research can be applied to similar machines for continuous improvement.

Abstract: The purpose of this study is to explore the use of laser additive manufacturing of bamboo powder to produce items with fewer variations than the traditional heat press method using a die. Although metal and resin powders are commonly used in powder additive manufacturing, bamboo powder presents unique challenges owing to its lack of material uniformity, low carbonization temperature, and dependence on pressure for adhesion. To address these issues, the appropriate laser power and irradiation time were determined by irradiating the laser at several power levels and examining its effects on the powder temperature and chemical changes during molding. The results indicated that rapid heating occurred at approximately 150 °C, and carbonization began at approximately 190 °C. As the energy loss for carbonization decreases with increasing laser power, this method is expected to be effective for producing bamboo products with fewer variations. In addition, restriction of continuous oxygen inflow by the glass plate lid makes it feasible to prevent heat generation and carbonization. Furthermore, pressurization by the glass plate makes it feasible to improve adhesion. Future research will focus on the suppression of carbonization by inert gas and heating at low temperatures for long periods of time, as well as the effects of different magnitudes of pressure on the process.

Abstract: In recent years, as global environmental problems have become increasingly serious, the concept of sustainable development, such as the 3Rs, has gained importance. Against this backdrop, machinery and equipment are becoming smaller, lighter, more sophisticated, and multifunctional, with highly integrated products increasingly requiring the machining and assembly of minute mechanical parts. However, the relatively large amounts of servo standby power generated by small machine tools during operation highlight the need for machining methods that reduce power consumption. In this study, we developed a novel 5-axis controlled machine tool equipped with an idling-stop function in the feed-driving system to reduce the power consumption of machining processes. Since this function stops the servo lock of the feed axis, it was unclear whether the same machining accuracy could be maintained as with the original setup. Therefore, in the present study, we measured straight cutting and endpoint areas using a laser microscope and an acceleration sensor and examined the change in machining accuracy due to the idling-stop function. It was found that when the idling-stop was turned off, vibration occurred, resulting in excessive cutting.

Abstract: The purpose of this study is to clarify the effect of the sparsity of the glass cloth that makes up the printed wiring board (PWB) on the shape of the laser-processed holes. In addition, pyrolyzed resin and hot glass fibers are ejected during processing. We investigated how this phenomenon changes depending on the position of laser irradiation on the glass cloth. PWBs consist of copper foil and insulation layers, which are composite materials composed of a glass cloth and epoxy resin. Because materials with different physical properties are processed simultaneously, the processing phenomena become extremely complex. In this study, we removed the copper foil by etching and performed laser drilling only in the insulation layer to investigate the effect of glass fibers on the shape of the machined holes. Simultaneously, the relationship between the shape of the machined hole and the ejecta generated during machining was investigated using a high-speed camera to capture images of the ejecta generated during machining. As a result, it was found that the diameter and roundness of the machined hole changed depending on the sparseness and density of the glass cloth. In addition, it was found that there are two mechanisms for the removal of glass cloth and that these mechanisms change the shape of the machined hole. Finally, it was found that these changes in the shape of the machined hole could be inferred from the ejecta.