外文翻譯---新工具使新機(jī)器設(shè)計(jì)-wenkub
2023-05-19 09:32:29 本頁(yè)面
【正文】 t concentration to achieve the fine grain structure and the material’s strength properties. Cobalt reacts with aluminum at elevated temperatures, which causes the aluminum to chemically bond to the exposed cobalt of the tool material. Once the aluminum starts to adhere to the tool, it quickly forms a builtup edge on the tool rendering it ineffective. The secret is to find the right balance of cobalt to provide adequate material strength, while minimizing the exposed cobalt in the tools for aluminum adherence during the cutting process. This balance is achieved using coarsegrained carbide that provides a tool of sufficient hardness so as to not dull quickly when machining aluminum while minimizing adherence. Tool coatings The second tool design element that must be considered when trying to minimize the builtup edge is the tool coating. Tool coating choices include TiN, TiAIN, AITiN, chrome nitrides, zirconium nitrides, diamond, and diamondlike coatings(DLC). With so many choices, aerospace milling shops need to know which one works best in an aluminum highspeed machining application. The Physical Vapor Deposition (PVD) coating application process on TiN, TiCN, TiAIN, and AITiN tools makes them unsuitable for an aluminum application. The PVD coating process creates two modes for aluminum to bond to the tools――the surface roughness and the chemical reactivity between the aluminum and the tool coating. The PVD process results in surface that is rougher that the substrate material to which it is app lied. The surface”peaks and valleys” created by this process causes aluminum to rapidly collect in the valleys on the tool. In addition, the PVD coating is chemically reactive to the aluminum due to its meta
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