The recent crisis of environmental pollution and resource depletion has become a major global issue, resulting in an increasing interest in remanufacturing in many countries. However, manufacturing for environmental protection is considered an additional cost factor by most companies. Therefore, governments worldwide have actively implemented remanufacturing policies to encourage the participation of numerous companies in the remanufacturing industry. As an eco-friendly technology, remanufacturing has impacted the environmental improvement and resource savings by reducing raw materials and production processes. In particular, the effect of machine tool and automobile part remanufacturing is very remarkable, since most parts are reusable. In this study, the standardization technology for remanufacturing process of machine tools is developed by remanufacturing of used vertical machining center. Based on the work operation sheet for establishing the process, the remanufacturing process chart and program were developed. The performance evaluation of machining centers before and after remanufacturing was also executed, to check the performance improvement of the remanufactured product. The performance evaluation criteria were established to improve reliability.

Bearings having a small clearance during normal operation are selected. In some cases, bearings having a negative clearance when mounted are selected, to generate internal stress which enables achieving various effects. This so-called preload can be applied only to rolling bearings and not sliding ones. The performance of bearings is greatly affected by the applied preload. Application of a heavy preload to enhance the stiffness at the spindle undermines the high-speed rotation performance. In contrast, when a light preload is applied for high speed rotation, the stiffness is undermined. Therefore, a variable preload method is required. This study aims to develop a variable preload device using a linear actuator of the ball screw type, and to perform the performance evaluation of the developed device. Our studies verified that the proposed device worked satisfactorily.

Recently, the problem of the accumulation of fine sludge from the cutting oil generated during machining processes has become a major threat to the environment. The fine sludge has adverse affects on the human body and the environment, and significantly contributes to marine pollution. However, a microfiltration technique that can process the sludge still needs to be studied and developed on a global scale. Therefore, it is necessary to develop eco-friendly equipment such as an ECO vacuum filter system and eco-friendly technologies for processing cutting oil. In this study, a structural analysis was carried out using a finite element method (FEM). Improved models of the suction chamber for the ECO vacuum filter system were proposed based on the analysis of the displacement and stress of the system. The model with the best result was then optimized using the commercial software, ANSYS. It was confirmed that, in the optimized model, displacement and stress were reduced in comparison with the initial model. Finally, the structural stability of the optimized model was verified through analysis.