Surface roughness is one of the important indicators for measuring the surface quality of workpieces, which directly affects the fitting performance, wear resistance, corrosion resistance, and appearance quality of the parts. Therefore, accurate detection of surface roughness is of great significance for ensuring product quality and improving production efficiency. This article will introduce several commonly used surface roughness detection methods and their principles and applications.



I. Basic concept of surface roughness



Surface roughness refers to the degree of height and depth of the smaller spacing and minor peaks and valleys on the surface of the workpiece. It is usually represented by parameters such as Ra (arithmetic mean deviation of profile), Rz (maximum height of profile), etc. Ra is the most commonly used roughness parameter, indicating the arithmetic mean of the absolute value of the deviation of the profile from the mean line within the sampling length.



II. Contact detection methods



1. Contact-type roughness meter

The contact-type roughness meter is the most widely used type of contact detection equipment at present. Its working principle is to use a diamond probe with high sensitivity to slide slowly along the surface to be measured, convert the change of the surface contour into an electrical signal through the sensor, and then amplify and process the signal to display the roughness value.



Advantages: High measurement accuracy; suitable for various metals and non-metallic materials.

Disadvantages: May cause surface damage to soft materials; not suitable for small or complex-shaped parts.



III. Non-contact detection methods



1. Optical interference method

This method utilizes the interference principle of light, obtaining surface topography information through the interference fringes of the reference light and the reflected light from the surface to be measured. It is suitable for nanometer-level precision roughness measurement.



Advantages: Non-contact, high precision; suitable for ultra-smooth surfaces.

Disadvantages: High instrument cost; strict environmental requirements.



2. Laser scanning method

The laser roughness meter uses a laser beam to illuminate the surface to be measured and analyzes the surface roughness by receiving the change of the reflected light. It is suitable for rapid detection of large surface areas.



Advantages: Non-contact, fast response, and easy operation.

Disadvantages: Poor measurement effect on high reflectivity or transparent materials.



3. White light confocal method

White light confocal technology is an advanced non-contact three-dimensional surface measurement method, suitable for surface roughness analysis of precision parts and optical components.



IV. Comparison and Selection



The selection of appropriate detection methods should be comprehensively considered based on factors such as the material, shape, roughness range, and measurement accuracy requirements of the object to be measured. For example, contact probe type instruments are commonly used for general mechanical parts; precision optical components are more suitable for using optical interference or white light confocal methods.



V. Conclusion



With the continuous improvement of quality requirements for products in modern manufacturing industry, surface roughness detection technology is also developing and improving. From traditional contact measurement to modern high-precision non-contact measurement, each method has its applicable scope and limitations. Rational selection of detection means can not only improve detection efficiency, but also provide a strong guarantee for product quality control.



In summary, mastering the technology and methods of surface roughness detection is one of the key factors to improve manufacturing process level and achieve precision processing.