The purpose of this study is to fabricate a multi-stage, variable-section and high-speed of the cutting device for recycling carbon fiber from waste hydrogen storage tanks. In this study, a high precision cutting device is fabricated utilizes (i.e., multi-stage, variable-section, high-speed cutting function and a diamond wire tool) to cut various waste hydrogen storage tank carbon fibers into scrap in a short period of time. The fabricated items include the development of diamond wire tools and wheels, cutting feed systems, structural frames, cooling system applications, and hydrogen tank fixing systems. The rotational speed of multi-stage wheel is in range of 0~600 rpm, and feed speed of diamond wire cutting tools is in range of 10–80 mm/min. The results showed that a new precision cutting device is able to cut the waste hydrogen storage tanks more than 400 pieces of performance indicator scrap (200×200 mm) within 8 hours of the cutting time. This confirmed that a new fabricated cutting device is a high speed cutting machine that is feasible for application in waste hydrogen storage tanks recycling in stead of conventional cutting device.

This research investigates into using a highly efficient magnetic abrasive finishing (MAF) method to refine the surface of an Inconel 625 bar intended for use as a stem in a hydrogen solenoid valve. In contrast to the previous choice of STS 316 material, Inconel 625 was selected due to its superior properties. The cylindrical surface of Inconel 625 bars underwent polishing using the super-fast MAF process, employing varying rotational speeds ranging from 1000 to 25,000 RPM and a potent magnetic field of 550 mT. The study evaluated the polishing outcomes concerning abrasive type, rotational speeds, and processing duration. The results demonstrated the achievement of an exceptionally smooth surface on the Inconel 625 bar, with the surface roughness (Ra) reduced significantly, reaching 0.03 μm under optimal conditions. These conditions included employing carbon nanotube (CNT) particles of 0.04g, PCD diamond abrasive of 1g, Fe of 9g, 0.5g of light oil, and a processing time of 16 minutes at 15,000 RPM. Furthermore, Ansys analysis confirmed the mechanical integrity of the polished Inconel 625 bar, exhibiting suitable strain, equivalent stress, and safety factors. This substantiates the feasibility of employing Inconel 625 bars in hydrogen tanks, surpassing the conventional STS 316L bars.