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Self-lubricanting cold forging tools

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In recent years, larger, more complex parts have been successfully cold forged due to improvements in forming equipment, die and workpiece materials, die coatings, and process design. In addition to the savings in energy costs, modern cold forging enables parts to be produced to near net shape [1]. Working conditions of forging tools have become severer with the years and it has been required for forging tools used to this end to increase the hardness, wear resistance and heat resistance. A typical shape of the tools exhibits an assembling in which a Cemented Carbides (CC) or High Speed Steel Insert (HSS) mounted into the casing. In these CC and HSS tools, the surface of the insert is ordinarily coated by CVD/PVD methods [2]. Many factors influence component accuracy in the form of systematic and random dimensional errors in the cold forming processes. There are four important factors that affect the component systematic errors, i.e.: imperfection of the material plastic flow, elastic deformation of the press system, elastic–plastic deformation and thermal behaviour of the tools and component [3]. The later two factors are most important and relevant to process and tool design of formed components. These effects become evident during different stages in the cold forming process, typically including forming, unloading, ejection and cooling. The repetitive production cycles in the industrial practice will bring further issues of dimensional changes due to tool wear and temperature increase developed over time. Thus, the tool wear resistance is one of the most important requirements.[...]

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