Research on micro-deep drawing process of concial part with ultra-thin copper foil using multi-layered DLC film-coated die

During the miniaturization of specimen size, lubrication plays a very important role in microforming process. Size effect of friction occurs clearly when a kind of liquid lubricant is applied, and the ultra-thin sheet is easily thinned and even broken in micro-deep drawing. Diamond-like carbon film (DLC film) gains more and more attention for its advantages such as low coefficient of friction and high wear resistance. In the investigation, functionally graded multi-layered DLC films were deposited on die surface by plasma ion implantation. The properties of DLC films were studied by atomic force microscopy, Raman spectroscopy, nano-indentation test, and ball-disc test. It was found the DLC film prepared at voltage of 13.5kV owns low friction coefficient and high wear resistance. Then, surfaces of punch for deep drawing and female die were modified by depositing functional-graded multi-layered DLC film with a voltage of 13.5kV. Micro-deep drawing tests were performed, and the distribution of thickness etc. was analyzed. As a result, micro-concial parts with good surface quality and uniform distribution of thickness were obtained. This means that multi-layer DLC film is helpful for improving the quality of ultra-thin sheet part.