Tham khảo tài liệu 'volume 18 - friction, lubrication, and wear technology part 9', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Stylus Load and Surface Deformation. The logical parameters that determine whether surface damage will be caused by stylus load are the surface hardness the stylus force the stylus tip width and to a lesser extent the stylus speed. A stylus tip width of 1 m 40 in. should not produce detectable damage on metal surfaces as soft as gold as long as the stylus force is smaller than about mN. Many types of stylus instruments use stylus forces of mN and higher but these are normally used with stylus tip sizes on the order of 10 m 400 in. . Because the pressure is inversely proportional to the area of contact the pressure on the surface caused by stylus loading is smaller for a 10 m 400 in. stylus with a mN force than it is for a 1 m 40 in. stylus with a mN force. Even if the stylus leaves a visible track the resulting profile is likely to be accurate because the variation in the depth of the track over the surface should be significantly smaller than the depth itself. However if a skid is used for stylus profiling the measured surface can be seriously damaged by the skid whose loading is hundreds of times larger than the stylus loading. The above discussion pertains only to plastic or irreversible deformation of the surface by stylus loading. Characterizing the elastic or reversible deformation Ref 6 is much more difficult but the elastic deformation is expected to be very small Ref 42 . In a study of plastic damage Song and Vorburger Ref 39 measured a 2160 lines mm gold grating with a m 20 in. stylus tip width. When the stylus loading increased from to 100 N the grating profile in the same position was attenuated Fig. 14a-d . When the stylus loading was reduced again to N Fig. 14e most of the periodic structure of the profile in Fig. 14 a had been plastically eliminated by the previous loading conditions and did not reappear. However a few of the fine peaks did reappear and the difference between the profiles in Fig. 14 d and 14 e suggests .
