How to Understand Gloss and Roughness?
1. The difference between gloss and roughness
Surface gloss refers to the intensity of the light reflection on the object surface. Seeing with the naked eye, the surface diffuse reflection is strong, the closer to the mirror effect, the gloss is high. Otherwise the surface diffuse reflection is weak, the gloss is low. Therefore, gloss is also called specular gloss. The influencing factors of surface glossiness are related to the physical properties of the surface and the chemical properties of the materials used on the surface. The method of detecting the specular gloss of the surface of an object requires the use of a surface gloss meter.
Surface roughness refers to the smaller pitch and unevenness of micro peaks and valleys that the processed surface has. The distance between two peaks or two valleys (wave distance) is very small (below 1mm) and it belongs to micro-geometry error. The smaller the surface roughness, the smoother the surface.
Surface roughness is generally formed by the processing method used and other factors, such as friction between the tool and the part surface during processing. Due to the different processing methods and workpiece materials, the depth, density, shape and texture of the marks left on the processed surface are different.
Surface roughness is closely related to the matching properties, wear resistance, fatigue strength, contact stiffness, vibration and noise of mechanical parts. It has an important impact on the service life and reliability of mechanical products. The general label is Ra.
2. The relationship between gloss and roughness
The object surface is not an absolutely smooth surface. Its specular reflectivity (that is, gloss) depends not only on the refractive index of the object, but also on the surface roughness. When the surface roughness is greater than the incident light wavelength, in addition to specular reflection, the surface also has diffuse reflection. The rougher the surface, the more diffuse reflection, the corresponding amount of specular reflection decreases and the gloss becomes weaker. The surface roughness of the measured surface will directly affect the accuracy of the measurement.
In addition, the surface roughness will have varying degrees of influence on the coating of parts, thermal conductivity and contact resistance, reflection ability and radiation performance, resistance to the flow of liquids and gases.
3. How to detect the object surface gloss?
A surface gloss meter can be used to detect the specific gloss of the object surface. The Linshang LS192 surface gloss meter is a high-precision glossiness measurement device manufactured in accordance with the ISO-2813 standard. The surface gloss meter is suitable for the measurement of specular gloss of paint, ink, plastic, stone, floor, wooden furniture surface, etc. It is a surface gloss meter produced in accordance with the National Verification Regulation JJG 696-2002 "Specular Glossmeters and Gloss Plates", and all indicators meet the requirements of the first-class working machine in the measurement verification regulations.