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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It is therefore important to ansk the measurement conditions when reporting roughness data. All the parameters are based on two-dimensional standards that are extended to three dimensions. 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.

Values numerically greater than 1. With this definition the Stdi value is always between 0 and 1. The spatial properties are described by five parameters.

The calculated RMS roughness between anis corresponds to the square root of the sum of all pixels in the 2D Power Spectrum Image between two concentric circles b461 with the radius of the inverse wavelength of the cursors in the IAPSD graph.

Note, also that roughness values depends strongly on measurement conditions especially scan range and sample density.

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. Surfaces with very dominant directions will have Stdi values close to zero and if the amplitude sum of all direction are similar, Stdi is close to 1.

## ANSI-ASME B46.1-1985.pdf

Some of the parameters depend on the definition of a local minimum and a local maximum. These parameters reflect slope gradients and their calculations are based on local z-slopes.

In principle, the texture aspect ratio has a value between 0 and 1. Having found r 0. The hybrid parameters can be described graphically by the above figure.

### Roughness Parameters

The Texture Aspect Ratio Parameters, Str20 and Str37are used to identify texture strength uniformity of texture aspect. The result is called the angular spectrum. 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 first parameter is calculated directly from the image, while the remaining are based on the Fourier spectrum.

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 amplitude sum, A aat a line with the angle, ais defined as:.

For all surfaces S ci is between 0 and 0.

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

Note,that negative peak artifacts may anzi this parameter to be underestimated and in such cases it might be appropriate to b46. some noise filtering. The angular spectrum is calculated by the following formula:. They are defined as the height difference between the highest and lowest pixel in the image. The table lists the roughness parameters by their symbol, name, corresponding 2D standard and unit. The functional parameters for characterizing bearing and fluid retention properties are described by six parameters.

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:. The Projected Area, S2Aexpresses the area of the flat x,y plane as given in the ani of R When there are less than five valid maximums or five absi minimums, the parameter is not defined. These lines are marked Z 0. For images consisting of parallel ridges, the texture direction is parallel to the direction of the ridges.

The Reduced Summit Height, Spkis the height of the upper left triangle.

Three parameters are calculated based on this figure. With this definition Srwi is always between 0 and 1. For all surfaces S vi is between 0 and 0. These parameters are the density of summits, the texture direction, the dominating wavelength and two index parameters.

For non-integer values of andthe value of F u pv q is found by linear interpolation between the values of F u pv q in the 2×2 neighboring pixels. Note, that since SPIP version 4. The fractal dimension can also be evaluated from 2D Fourier spectra by application of the Log Log function.

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:.

This may be the case for image containing well organized linear structures. Shw corresponds to the radius r 0.