ASME B / ANSI/ASME B – Surface Texture and Gaging for Screw Threads Package ASME B and ANSI/ASME B The ASME B46 1 ANSI ASME. Find the most up-to-date version of ANSI B at Engineering The American Standard for Surface Texture in ANSI B gives Ra as the standard surface finish designation. In most applications where RMS is called.

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Large S bi indicates a good bearing property. The Ten Point Height, S10 zis defined as the average height of the five highest local maximums plus the average height of the five lowest local minimums:. The calculated RMS roughness between cursors corresponds to the square root of the sum of all pixels in the 2D Power Spectrum Image between two concentric circles each with the radius of the inverse wavelength of the cursors in the IAPSD graph.


Some of the parameters depend on the definition of a local minimum and a local maximum. Three parameters are calculated based on this figure. For b446.1 surfaces S ci is b461. 0 and 0. This may be the case for image containing well organized linear structures. Fourier spectrum and the angular and radial spectra.

The angular spectrum is calculated by the following formula:. Dominant Radial Wave Length. For these parameters we require the images to be quadratic.

ASME B / ANSI/ASME B – Surface Texture and Gaging for Screw Threads Package

The radial spectrum is calculated by the following formula:. The Core Roughness Depth, Skis the height difference between the intersection points of the found least mean square line.


The Dominating Radial Wavelength, Srwcorresponds to the semicircle with radius, r maxhaving the highest amplitude sum, b anso With this definition the Stdi value is always between 0 and 1. The Surface Bearing Index, S biis defined as:. Area Root Mean Square Slope. anei

ANSI-ASME B46.1-1985.pdf

Note,that negative peak artifacts may cause this parameter to be underestimated and in such cases it might be appropriate to perform some noise filtering. The Fractal Dimension, Sfd is calculated for the different angles by analyzing the Fourier amplitude spectrum; for different angles the amplitude Fourier profile is extracted and the logarithm anei the ansii and amplitude coordinates calculated.

If the surface is fractal the Log Log graph should be highly linear, with at negative slope. All six parameters are defined from the surface bearing area ratio curve shown in the figures below. The line having the angle, awith the highest amplitude sum, Amaxis the dominating direction in the Fourier transformed image and is perpendicular to the texture direction on the image.

The advantage of this is that deviations from the absi plane can be quantified better when setting the bearing plane to zero see how this is done in the B461 Correction Dialog section. Here, a local minimum is defined as a pixel where all eight neighboring pixels are higher and a local maximum as a pixel where all eight neighboring pixels are lower. The fractal dimension, D, for each direction ans then calculated as. Parameters associated with the two-dimensional DIN standard are also calculated based on the bearing area ratio curve.


Having found r 0. For an anisotropic surface the correlation length is in the direction perpendicular to the surface lay.

Before the calculation of the roughness parameters we recommend carrying out a slope correction by a 2 nd or 3 rd order polynomial plane fit. The spatial properties are described by five parameters. If there is a very dominating wavelength, Srwi is close to 0, and if there is no dominating wavelength, it is close to 1. For all surfaces S vi is between 0 and 0.

As there are no pixels outside the borders of the image there are no local minimums or local maximums on the borders. With this definition Srwi is always between 0 and 1.

Note, that since SPIP version 4. The Cross Hatch AngleSch is the found angle of a cross hatch pattern typically created in seen in cylinder liners and created by a honing process used to ensure proper lubrication.

The Mean Half Wavelength, Shwis based on the integrated radial spectrum:. The amplitude sum, b ralong a semicircle with the radius, r ahsi, is.

These parameters are the density of summits, the texture direction, the dominating wavelength and two index parameters.