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Reference for Surface Roughness Grades and Applications in Metals

Reference for Surface Roughness Grades and Applications in Metals

Reference for Surface Roughness Grades and Applications in Metals

Surface roughness is a critical parameter in metal manufacturing, directly influencing product functionality, durability, and aesthetic appeal. Understanding roughness grades and their applications helps engineers select optimal surface finishes for various industries. This article provides a comprehensive guide to metal surface roughness grades, supported by detailed tables and practical application scenarios.

What Is Surface Roughness?

Surface roughness refers to the microscopic irregularities of a metal surface, measured by parameters like Ra (arithmetic mean roughness) and Rz (average peak-to-valley height). These irregularities result from manufacturing processes (e.g., machining, casting, polishing) and affect:

The most widely used parameter is Ra, measured in micrometers (μm), which quantifies the average height deviation from the ideal smooth surface.

Surface Roughness Grades and Measurement Standards

Below is a table outlining the main surface roughness grades (by Ra value), corresponding Rz ranges, typical manufacturing methods, and visual characteristics:

Roughness GradeRa (μm)Rz (μm)Manufacturing MethodsSurface Appearance
Ultra-Fine<0.1<0.5Lapping, superfinishing, electropolishingMirror-like, no visible defects
Fine0.1–0.80.5–5.0Grinding, honing, electrolytic polishingSmooth, no visible scratches
Medium0.8–6.35.0–40.0Milling, turning, boringVisible tool marks, no major imperfections
Coarse6.3–2540.0–160.0Sawing, planning, sandcastingRough texture, obvious machining marks
Very Coarse>25>160.0Flame cutting, rough forgingHighly irregular, porous surface

International Measurement Standards

Applications of Surface Roughness Grades in Metals

1. Ultra-Fine Surface (Ra < 0.1μm)

2. Fine Surface (Ra 0.1–0.8μm)

3. Medium Surface (Ra 0.8–6.3μm)

4. Coarse Surface (Ra 6.3–25μm)

5. Very Coarse Surface (Ra >25μm)

How to Choose the Right Surface Roughness

1. Functional Requirements

2. Corrosion Resistance

3. Cost Considerations

4. Industry Standards

Measurement Tools for Surface Roughness

Conclusion

Surface roughness is a fundamental factor in metal manufacturing, influencing both form and function. By matching roughness grades to application needs—from ultra-fine finishes for medical implants to coarse textures for heavy machinery—engineers can optimize performance and cost. For custom surface finishing solutions or equipment recommendations, consult our team of manufacturing experts.

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