How to detect the surface finish of equipment components

The relevant evaluation basis is baseline 1, and the sampling length l is used to determine a segment of baseline length with surface roughness characteristics. The sampling length should be selected based on the actual surface condition and texture characteristics of the part, choosing a length that can reflect the features of surface roughness. When measuring the sampling length, it is necessary to consider the overall direction of the actual surface contour. The sampling length and evaluation length show that this contour line has surface roughness and shape errors; different height values are obtained when different sampling lengths are used. The sampling length is specified and selected in order to limit and reduce the influence of surface waviness on the measurement results of surface roughness. 2. Evaluation length Gp: A length necessary for evaluating the profile, which may include one or several sampling lengths. Since the surface roughness of different areas on a part’s surface is not necessarily uniform, a single sampling length often fails to adequately reflect a particular roughness characteristic; therefore, several sampling lengths must be taken across the surface in order to assess it. Generally, 2 or 3 sampling lengths are used. The reference line is the line specified for evaluating surface roughness parameters, and it serves as the basis for two-dimensional assessment of surface roughness. There are two types of baseline: (1) the least squares median line of the contour: a baseline that has the shape of the geometric contour and divides it, such that the sum of the squares of the deviations of the points on the contour from this baseline is minimized over the sampling length (see Figure 4-2). (2) The arithmetic mean median line of the contour: a baseline that has the shape of the geometric contour and follows the direction of the contour over the sampling length. Within the sampling length, the contour is defined by this line, so that the areas on the upper and lower sides are equal. That is: F, plus F: +F3+… plus all F’s = F, }+Fz’ plus F3’ plus… + just ‘. Theoretically, the least squares median line is the only ideal reference line, but it is difficult to obtain in practical applications; therefore, the arithmetic mean median line of the contour is generally used as a substitute, and a straight line with an approximately correct position can be used during measurement. Figure 4-2: Least squares median line of the profile. Figure 4-3: Arithmetic mean median line of the profile. Single peaks and single valleys of the profile: A single peak of a profile refers to the portion of the profile between the two lowest points adjacent to each other. The single valley of a contour refers to the part of the contour between the highest points of two adjacent contours. A single peak together with the adjacent valley forms a micro-irregularity, known as a single micro-irregularity. Single peak of the profile, single valley of the profile, single peak of the profile, single valley of the profile. 5. Profile peaks and profile valleys: A profile peak refers to the part of the profile that intersects the midline within the sampling length; it is the section of the profile that extends outward from the two adjacent intersection points. In other words, a profile peak is the part of the profile located on the side of the midline. A contour valley refers to the part of the contour that intersects the midline within the sampling length, and extends inward by connecting the two adjacent intersection points

Surface finish has been redefined as roughness; there are no precise instruments available on site (and those that do exist are complex and cumbersome). Generally, one can rely on experience, by observing the texture and brightness of the machined surface, etc. For less precise applications, it is possible to feel the surface by hand.