機(jī)械外文翻譯材料的機(jī)械加工性-資料下載頁
2025-05-14 01:08本頁面
【正文】 y be achieved with a jet of air, vapor mist, or watersoluble oils. Residual stresses may develop during machining. To relieve these stresses, machined parts can be annealed for a period of time at temperatures ranging from to (to), and then cooled slowly and uniformly to room temperature.Thermosetting plastics are brittle and sensitive to thermal gradients during cutting. Their machinability is generally similar to that of thermoplastics.Because of the fibers present, reinforced plastics are very abrasive and are difficult to machine. Fiber tearing, pulling, and edge delamination are significant problems。 they can lead to severe reduction in the loadcarrying capacity of the ponent. Furthermore, machining of these materials requires careful removal of machining debris to avoid contact with and inhaling of the fibers.The machinability of ceramics has improved steadily with the development of nanoceramics and with the selection of appropriate processing parameters, such as ductileregime cutting .Metalmatrix and ceramicmatrix posites can be difficult to machine, depending on the properties of the individual ponents, ., reinforcing or whiskers, as well as the matrix material.4. Thermally Assisted MachiningMetals and alloys that are difficult to machine at room temperature can be machined more easily at elevated temperatures. In thermally assisted machining (hot machining), the source of heat—a torch, induction coil, highenergy beam (such as laser or electron beam), or plasma arc—has been focused on cutting tool before a piece of is: (a)low cuting force,(b) increased tool life, (c) use of inexpensive cuttingtool materials, (d) higher materialremoval rates, and (e) reduced tendency for vibration and chatter.It may be difficult to heat and maintain a uniform temperature distribution within the workpiece. Also, the original microstructure of the workpiece may be adversely affected by elevated temperatures. Most applications of hot machining are in the turning of highstrength metals and alloys, although experiments are in progress to machine ceramics such as silicon nitride. 5. SummaryMachinability is usually defined in terms of surface finish, tool life, force and power requirements, and chip control. Machinability of materials depends not only on their intrinsic properties and microstructure, but also on proper selection and control of process variables.6 / 6
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