Surface Texture SURFACE TEXTURE American National Standard Surface Texture (Surface Roughness, Waviness, and Lay) Machinery's Handbook, 31st Edition
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American National Standard ANSI/ASME B46.1-2009 is concerned with the geomet- ric irregularities of surfaces of solid materials, physical specimens for gaging roughness, and the characteristics of stylus instrumentation for measuring roughness. The standard defines surface texture and its constituents: roughness, waviness, lay, and flaws. A set of symbols for drawings, specifications, and reports is established. To ensure a uniform basis for measurements, the standard also provides specifications for Precision Refer - ence Specimens, and Roughness Comparison Specimens, and establishes requirements for stylus-type instruments. The standard is not concerned with luster, appearance, color, corrosion resistance, wear resistance, hardness, subsurface microstructure, sur- face integrity, or many other characteristics that may govern considerations in specific applications. The standard is expressed in SI metric units, but US customary units may be used with out prejudice. The standard does not define the degrees of surface roughness and waviness or type of lay suitable for specific purposes, nor does it specify the means by which any degree of such irregularities may be obtained or produced. However, criteria for selection of surface qualities and information on instrument techniques and methods of producing, controlling and inspecting surfaces are included in Appendixes attached to the standard. The Appendix sections are not considered a part of the standard: they are included for clarification or information purposes only. Surfaces, in general, are very complex in character. The standard deals only with the height, width, and direction of surface irregularities because these characteristics are of practical importance in specific applications. Surface texture designations as delineated in this standard may not be a sufficient index to performance. Other part characteristics such as dimensional and geometrical relationships, material, metallurgy, and stress must also be controlled. Definitions of Terms Relating to the Surfaces of Solid Materials.— The terms and ratings in the standard relate to surfaces produced by such means as abrading, casting, coating, cutting, etching, plastic deformation, sintering, wear, and erosion. Error of form is considered to be that deviation from the nominal surface caused by errors in machine tool ways, guides, insecure clamping or incorrect alignment of the workpiece or wear, none of which are included in surface texture. Out-of-roundness and out-of-flatness are examples of errors of form. See ANSI/ASME B89.3.1-1972 (R2003) for measurement of out-of-roundness. Flaws are unintentional, unexpected, and unwanted interruptions in the topography typical of a part surface and are defined as such only when agreed upon by buyer and seller. If flaws are defined, the surface should be inspected specifically to determine whether flaws are present, and rejected or accepted prior to performing final surface roughness measurements. If defined flaws are not present, or if flaws are not defined, then interruptions in the part surface may be included in roughness measurements. Lay is the direction of the predominant surface pattern, ordinarily determined by the production method used. Roughness consists of the finer irregularities of the surface texture, usually including those irregularities that result from the inherent action of the production process. These irregularities are considered to include traverse feed marks and other irregularities within the limits of the roughness sampling length. Surface is the boundary of an object that separates that object from another object, sub stance or space. Surface, measured is the real surface obtained by instrumental or other means.
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