Common methods for measuring surface roughness

The measurement of surface roughness generally has the following common methods:

1. Comparative method

Compare the surface roughness comparison sample with the measured surface based on vision and touch to determine which value the measured surface roughness is equivalent to, or measure the change in reflected light intensity to evaluate the surface roughness (see laser length measurement technology).

2. Stylus method

A diamond stylus with a tip radius of curvature of about 2 microns is used to slowly slide along the measured surface. The up and down displacement of the diamond stylus is converted into an electrical signal by an electrical length sensor. After amplification, filtering, and calculation, the surface roughness is indicated by a display instrument. Degree value, a recorder can also be used to record the profile curve of the measured section.

3. Light sectioning method

The light strip formed after the light passes through the slit is projected onto the measured surface, and the surface roughness is measured based on the contour curve formed by the intersection line with the measured surface. After the light emitted from the light source passes through the condenser, slit, and objective lens, the slit is projected onto the measured surface at an inclination angle of 45° to form a cross-sectional profile figure of the measured surface. This figure is then amplified through the objective lens 2 and projected onto the measuring surface. On the paddle board. Use the micrometer eyepiece and reading drum to first read the h value, and then calculate the H value. The surface roughness measurement tool that applies this method is called a light-section microscope. It is suitable for measuring surface roughness of RZ and Ry between 0.8 and 100 microns. It requires manual point selection and has low measurement efficiency.

4. Intervention method

The principle of light wave interference is used to display the shape error of the measured surface as an interference fringe pattern, and a high-magnification microscope is used to amplify the microscopic parts of these interference fringes and measure them to obtain the roughness of the measured surface. The surface roughness measurement tool that applies this method is called an interference microscope. This method is suitable for measuring surface roughness with Rz and Ry of 0.025 to 0.8 microns.

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