Surface Texture Analysis  Standards

Surface Texture Analysis Standards PowerPoint PPT Presentation


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Outline. Introduction- Measurement TechniquesSession 1 Preprocessing

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Surface Texture Analysis Standards

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1. Surface Texture Analysis & Standards Bala Muralikrishnan1 & Jay Raja2 Dept of ME&ES University of North Carolina at Charlotte 1 [email protected], [email protected], 301-975-3789 2 [email protected], 704-687-4390 ASPE Tutorial 2004

3. Introduction Measurement Techniques

4. Classification of Surface Texture Measurement Methods

5. Contacting Stylus Method(2D) Principle It is a surface topography measurement method where the probe is a contacting stylus whose vertical motion is converted into an electrical signal as a function of lateral position.

8. Contacting Stylus Method(3D) Principle It is a surface topography measurement method where the probe is a contacting stylus whose vertical motion is converted into an electrical signal as a function of lateral position.

9. Principle An optical microscope with illumination of a known wavelength integrated with an interferometry attachment produces multiple optical images with interferometric fringes from which the profile or topography image is obtained Phase Shifting Interferometry

10. Vertical Scanning Interferometry (Scanning white light interferometry) Principle An optical microscope with broad band illumination integrated with an interferometry attachment is scanned in Z-direction w.r.t the surface to produce an equal interferometric path condition for each point in the image, from which the surface topography is calculated.

11. Focus Sensing Confocal Microscopy Principle The surface height at each point is determined by sensing its vertical position w.r.t optimum focus in an optical microscope and an areal topography image is then obtained by imaging multiple points.

12. Chromatic Length Aberration (CLA) Confocal Microscopy Principle The height at a point is determined by integrating a spectrometer into an optical microscope and sensing the chromatic dispersion of white light reflected from the surface.

13. Structured Light and Triangulation Methods Principle A light image of known structure or pattern is cast on a surface and the pattern of reflected light together with knowledge of the incident structured light allows one to determine the surface topography.

14. Angle Resolved Scanning Electron Microscopy (SEM) Principle Local gradients of a surface are determined by angular distributions of secondary electron emission intensity and an areal topography image is obtained by integration of these local gradients.

15. SEM Stereoscopy Principle Two SEM images are taken of a surface oriented at slightly different angles and the comparison of the two images yields a stereo effect from which surface topography can be determined.

16. Scanning Tunneling Microscopy (STM) Principle The determination of surface arises from the height-related variations in electrical tunneling current produced between a conducting surface and a conducting tip placed very close to it, with a constant voltage maintained between them.

17. Atomic Force Microscope (AFM), Scanning Force Microscope (SFM) Principle The surface height is sensed from the mechanical force of attraction or repulsion between a probe tip and a surface.

19. Area-Integrating Method Surface measurement method that measures a representative area of a surface and produces numerical results that depends on area-integrated properties of the surface texture.

20. Angle Resolved Scatter Principle The light scattered from the surface is collected as a function of incident angle or scattered angle or both and the measured function may be used to calculate rms roughness, power spectral density and other roughness parameters.

21. Lasercheck – Tropel Metrology instruments

22. Amplitude – Wavelength (A-W) Characteristics of a Surface and A-W Maps

23. Why Measure Surface Texture Functionally Important Process Control Quality Control Research and Development Contractual Obligation

24. Amplitude-Wavelength

25. A-W Maps A-W Map is a pictorial description of relevant amplitudes and wavelengths for A surface (think PSD) For an instrument (its work volume) For processes (in terms of tolerances) For function (think specification)

26. A-W Maps for Instruments Vertical range (Rv) and resolution (rv) Horizontal range (Rh) and resolution (rh) Horizontal datum (maximum slope Smax) Probe geometry (minimum radius of curvature Rmin)

27. Limits of surface measurement by stylus instruments & log AW space Vertical range (Rv) and resolution (rv) Rv and rv restrict amplitude. ie., Rv > 2A > rv Horizontal range (Rh) and resolution (rh) Rh and rh restrict wavelength. Ie., Rh > W > rh Horizontal datum Slope of flanks of the stylus (Ss) and maximum slope error of the datum (Sd) restrict surface slope that can be measured. ie., Ss > Smax > Sd Probe geometry Tip of radius of the stylus (Rs) and curvature error of the datum (Rd) restrict radius of curvature that can be measured. ie., Rd > Rmin > Rs

28. AW maps for Stylus instruments

29. Vertical range (Rv) and resolution (rv) Rv and rv restrict amplitude. Horizontal range (Rh) and resolution (rh) Rh and rh restrict wavelength. Wavelength is direct limiting factor in the case of optical probes. rh = 0.61?/NA for focused beam. rh = 1/e2 for unfocused beam. Horizontal datum Numerical aperture (NA) of an objective lens and maximum density of tilt fringes restricts maximum slope. ie., Smax < NA/2 Probe geometry Limits of surface measurement by optical probe instruments

30. AW maps for optical probe instruments

31. A-W maps

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