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.

Each point in the graph corresponds to the normalized power in a circle one frequency pixel wide in the squared FFT image the Power Spectrum Image. The spatial properties are described by five parameters. Shw corresponds to the radius r 0. The Roughness Average, S ais defined as:.

MIL-STD A NOTICE-2 SURFACE ROUGHNESS WAVINESS LAY

Values numerically greater than 1. The relative amplitudes for the different angles are found by summation of the amplitudes along M equiangularly separated radial lines, as shown in the figure below. The Reduced Summit Height, Spkis the height of the upper left triangle.

These parameters reflect slope gradients and their calculations are based on local z-slopes. The amplitude sum, b ralong a semicircle with the radius, ris.

The Projected Area, S2Aexpresses the area of the flat x,y plane as given in the denominator of R Large S bi indicates a good bearing property.

This may be the case for image containing well organized ansl structures. If the surface is fractal the Log Log graph should be highly linear, with at negative slope.

ANSI-ASME B46.1-1985.pdf

Mean HeightS mean is the mathematical mean height of all pixels. 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:. Znsi Surface Area, S3Aexpresses the area of the surface area taking the z height into account as given in the numerator of R The Dominating Radial Wavelength, Srwcorresponds to the semicircle with radius, r maxhaving the highest amplitude sum, b max: For images consisting of parallel ridges, the texture direction is parallel to the direction of the ridges.

Here, a local minimum is defined as a pixel where all eight neighboring pixels are b6.1 and a local maximum as a b46. where all eight neighboring pixels are lower. They are defined as the height difference between ans highest and lowest pixel in the image. The angular spectrum is calculated by the following formula:.

The fractal dimension can also be evaluated from 2D Fourier spectra by application of the Log Log function. Some of the parameters depend on the definition of a local minimum and a local maximum.

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. 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:.

As there are no pixels outside the borders of the image there are no local minimums or local maximums on the borders. Dominant Radial Wave Length. For a Gaussian height distribution S vi approaches 0.

Having found r 0. Parameters associated with the two-dimensional DIN standard are also calculated based on the bearing area ratio curve. If there is a very dominating wavelength, Srwi is close to 0, and if there is no dominating wavelength, it is close to 1. Valley Fluid Retention Index. Root Mean Square Gradient. Smaller values indicate broader height distributions and visa versa for values greater than 3. There are three hybrid parameters.

The amplitude sum, A aat a line with the angle, ais defined as:. The Density of SummitsSdsis the number of local maximums per area:. All the parameters are based on two-dimensional standards that are extended to three dimensions.

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. In principle, the texture aspect ratio has a value between 0 and 1. Fourier spectrum and the angular and radial spectra.

N46.1 these parameters we require the images to be quadratic. The Mean Half Wavelength, Shwis based on the integrated radial spectrum:.

Area Root Mean Square Slope. Three parameters are calculated based on this figure.

When there are less than five valid maximums or five valid minimums, the parameter is not defined.