The surface roughness

Surface roughness: refers to the machining surface with small spacing and small peak valley roughness. The distance between the two peaks or two troughs ( Wave from) Is small ( Below 1 mm) , with the naked eye is hard to distinguish, so it belongs to the micro geometry shape error. The smaller the surface roughness, surface more smooth. The size of the surface roughness, the use of mechanical parts performance has a great influence, mainly displays in the following aspects: (1) the surface roughness affect the abrasion resistance parts. Surface is rough, cooperate with the surface area of effective contact between the smaller, the greater the pressure, the faster the wear. (2) the surface roughness affect the stability of the nature. For clearance fit, the surface is rough, the more easy to wear and clearance in the working process of the gradually increase; Across full cooperation, due to the micro convex peak when assembling crowded flat, reduced the actual interference effectively, reduces the connection strength. (3) the surface roughness affect the fatigue strength of parts. Rough parts surface larger trough, they like horns gaps and cracks, is sensitive to stress concentration, which affect the fatigue strength of parts. (4) the surface roughness affect the corrosion resistance of parts. Rough surface, easy to make the corrosive gas or liquid by micro grooves on the surface of the valley into the metal lining, causing surface corrosion. (5) the surface roughness affect the sealing parts. Cannot fit closely between rough surface, the leakage of gas or liquid through the gap between the surfaces. In addition, the appearance of the surface roughness of parts, also has effect on the accuracy of measurement. The surface roughness Ra value the application scope of note: 1. Roughness codes I for the first transition style. It is the most close to, which is corresponding to the new national standard under a 1 of the series of values, such as the original finish ( The old gb) For del 5, Ra the maximum allowed from 6. 3. Therefore, without affecting the original surface roughness requirements, take the value for processing. 2. Roughness codes Ⅱ for 2 kinds of transitional way. It is the most close to, which is corresponding to the new national standard on a 1 of the series of values, such as the original finish for del 5, Ra maximum allowable values of the three. 2. Therefore, take the value improves the original surface roughness requirements and processing cost.