Study On The Typical Advanced Plastics Mold Steel And Investigation Of Technology In Polishing

Plastic products have been widely used in fields of light cars, electronic products and precision optical lens within decades, high precision demanding for plastic molds have been increasing consequently. The surface quality of polished molds is closely bound up with the appearance quality of plastic products. Therefore, the high-precision mirror polishing has been becoming the focus in the research field of molds, increasing by high demands for precision in modern industry. However, the polishing quality is not only determined by polishing equipment and technics, it is also largely affected by mold materials. This paper investigated the employment of one advanced plastics mold steel used commonly in the market, in order to further develop and apply this steel. The application of electrochemical polishing and its composite polishing technology on the mold polishing were summarized, and the development for the new environment friendly electrolyte was also primarily investigated.The quality on several similar grade mold steels of the typical advanced plastic mould steel 1.2083 in present market was synthetically analyzed, including chemical composition, micro-hardness, nonmetallic inclusions, surface roughness and micro-structure, etc. The results indicated that in terms of clean quality and uniform fine structure, the corrosion-proof mirror mould steel has excellent mirror polishing performance and corrosion-proof ability after electro-slag remelting and heat treatment.The macroscopic protuberance defects, the cavity and pit flaws on the surface of one typical 1.2083 mold were also analyzed. The morphology, structure and composition of the defects and the relationship with nonmetal inclusions were observed by Optical Microscopy and Scanning Field Emission Microscopy. The results show that the defects on the surface of the failure mould product were caused by kinds of nonmetal inclusions and inhomogeneous chemical composition in some area of this mold steel, which destroyed the matrix continuity during the polishing process. Multiphase nitride inclusions in the interior of the steels were firstly discovered that they directly affected the polishing quality of molds, and the desquamation mechanism of the inclusions and the formation mechanism of defects were discussed. The control measures of the metallurgy defect were also proposed.Combining the latest development of electrochemical polishing technology both here and abroad in recent years, the application of new-style electrochemistry and its composite polishing technology in the mold finishing field were also summarized. The mechanism of electrochemical polishing was introduced and it was pointed out that core question of electrochemical polishing are anode passivation and the property of the passive film. Contrasting by neutral electrolyte and acid electrolyte in existing conditions, the feasibility and reality of the development for less-acid electrolyte and the suggestions for further study were discussed.