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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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. With this definition the Stdi value is always between 0 and 1. The fractal dimension can also be evaluated from 2D Fourier spectra by application of the Log Absi function.

The Dominating Radial Wavelength, Srwcorresponds to the semicircle with radius, r maxhaving the highest amplitude sum, b max: Maximum Valley Depth Sv: We calculate Std from the Fourier spectrum. For Gaussian height distributions S ku approaches 3.

The Radial Wave IndexSrwiis a measure of how dominant the amsi radial wavelength is, and is defined as the average amplitude sum divided by the amplitude sum of the dominating wavelength:. Root Mean Square Gradient. The Surface Bearing Index, S biis defined as:. For all surfaces S ci is between 0 and 0. 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 of the frequency and amplitude coordinates calculated.

The line having the angle, awith the highest amplitude sum, Amaxis the dominating direction in the Fourier transformed image and is perpendicular to the h46.1 direction on the image. All the parameters are based on two-dimensional standards that are extended to three dimensions.


Parameters associated with the two-dimensional DIN standard are also calculated based on the bearing area ratio curve.

The first parameter is calculated directly from the image, while the remaining are based on the Fourier spectrum. If the surface is fractal the Log Log graph should be highly linear, with at negative slope.

ANSI-ASME B46.1-1985.pdf

Large S bi indicates a good bearing property. The functional parameters for characterizing bearing and fluid retention properties are described by six parameters.

The spatial properties are described by five parameters. The angular spectrum is calculated by the following formula:.

With this definition Srwi is always between 0 and 1. The reported fractal dimension is the average for all directions. If the angle of the ridges is turned clockwise, the angle is positive and if the angle of the ridges is turned anti-clockwise, the angle becomes negative.

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

The hybrid parameters can be described graphically by the above figure. The Mean Summit Curvature, S scis the average of the principal curvature of the local maximums on the surface, and is defined as:.

These lines are marked Z 0. Note, that since SPIP version 4. 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:. For a Gaussian height distribution S vi approaches 0. This parameter is only meaningful if there is a dominating direction on the sample.

For a surface with a dominant lay, the parameters will tend towards 0.

The Texture Direction IndexStdiis a measure of how dominant the dominating direction is, and is defined as the average amplitude sum divided by the amplitude sum of the dominating direction:.


Area Root Mean Square Slope.

Dominant Radial Wave Length. The Surfaces Area Ratio, S drexpresses the increment of the interfacial surface area relative to the area of the projected flat x,y plane:. These parameters reflect slope gradients and their calculations are based on local z-slopes.

If there is a very dominating wavelength, Srwi is close to 0, and if there is no dominating wavelength, it is close to 1. The amplitude sum, b ralong a semicircle with the radius, ris.

It is therefore important to include the measurement conditions when reporting roughness data. They are defined as the height difference between the highest and lowest pixel in the image. As there are no pixels outside the borders of the image there are no local minimums or local maximums on the borders. The table lists the roughness parameters by their symbol, name, corresponding 2D standard and unit.

Values numerically greater than 1. The Area Root Mean Square Slope, S dq6is similar to the Sdq but includes more neighbor pixels in the calculation of the slope for each pixel.

Wnsi result is called the angular spectrum. The Reduced Summit Height, Spkis the height of the upper left triangle. The Surface Area, S3Aexpresses the area of the surface area taking the z height into account as given in the numerator of R The Core Roughness Depth, Skis the height difference between the intersection points of the found least mean square line.

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.