Surface roughness not only affects the accuracy of processed products but also affects the gloss and texture of the surface. Therefore, it is one of the factors that affect product image and brand. Especially in the field of ultra-precision machining, not only machining accuracy is required, but also high surface treatment capabilities are required, so surface roughness is extremely important.
Below, we will focus on 5 specific aspects to explore how surface roughness influences product performance.
1. Providing a certain visual appearance and tactile sensation to the product's casing, vehicle dashboards, and processing panel surfaces is influenced by the differences in surface roughness. For example, steel plates used for automotive bodies undergo surface treatment to allow the paint to adhere without any "orange peel" effect and achieve a uniform appearance. Similarly, when purchasing products like smartphones or laptops, most people consider the aesthetics and touch, essentially selecting the surface smoothness and roughness of the metal casing.
2. The fatigue life of components that affect fatigue strength decreases with increasing surface roughness, especially in high-cycle fatigue conditions. In terms of the direction of surface roughness, circumferential roughness perpendicular to the stress direction has a more significant impact on fatigue strength compared to the axial direction. Surface roughness must be considered when evaluating the fatigue life of aluminum alloy products or designing high-fatigue life aluminum components.
3. Larger roughness can cause dirt to stick in metal recesses, making cleaning more challenging. In contrast, smooth surfaces are easier to clean due to their streamlined profiles. This is also one of the reasons why surface roughness plays a crucial role in industries such as food processing and pharmaceuticals: smoother surfaces are more hygienic and reduce bacterial adhesion.
4. Friction and wear of metal sheets depend on surface texture. Some wear occurs regardless of how well-lubricated two surfaces in relative motion (e.g., shaft and bearing) may be. Rough surfaces are more prone to wear and have higher friction force. High friction coefficients mean greater force is required during sliding compared to smooth surfaces. If the surface is rough, the peaks wear quickly, leading to a smoother surface, but this affects dimensional fit. Smaller roughness enhances the product's wear resistance while reducing friction. Moreover, roughness is critical for corrosion resistance and chemical resistance, as defects provide nucleation sites for cracking or corrosion.
5. Sealing performance or wear can be affected by roughness when two surfaces move in close contact with each other. In lubricated situations, it has been found that roughness valleys are necessary to accommodate lubricating oil. For example, using lip seals to prevent hydraulic oil leakage, if the surface is too smooth, it is difficult to maintain a fluid film between the shaft and seal. If the surface treatment is too rough, it may result in wear and subsequent failure.
