Metal Surface Finishing Guide: Sandblasting, Anodizing, PVD Coating, Passivation & Electroplating
Created on 05.21
Meta Description: A comprehensive guide to metal surface finishing processes including sandblasting, anodizing, PVD coating, passivation and electroplating, compare parameters, application scenarios and advantages to select the optimal solution for industrial metal parts. #metal surface finishing #sandblasting vs anodizing #PVD coating metal #metal passivation electroplating
Metal parts (stainless steel, aluminum alloy, titanium alloy, copper alloy) are widely used in automotive, new-energy, medical, and industrial equipment fields. Surface finishing is not only to improve appearance but also to enhance corrosion resistance, wear resistance, electrical conductivity, and biocompatibility—critical for part service life and industrial compliance. However, many customers struggle to select the right finishing process due to unclear process characteristics and mismatched material requirements. Based on years of industrial OEM experience, we systematically analyze five core metal surface finishing processes, including their technical parameters, application scenarios, advantages, and limitations.
1. Sandblasting (Dry/Wet)
Technical Parameters: Sand type (white corundum, glass beads, alumina); particle size 50-200 mesh; pressure 0.2-0.5MPa; surface roughness after processing: Ra 1.6-6.3μm (fine sandblasting: Ra 1.6-3.2μm).
Applicable Materials: All metal materials (316L stainless steel, AlSi10Mg, Ti-6Al-4V, copper alloy).
Core Application: Pre-treatment before coating/anodizing; matte surface finishing for functional metal parts; removing oxide layers and burrs from die-casting and CNC parts.
Advantages: High efficiency, low cost, uniform surface effect; no dimensional loss; improves coating adhesion.
Limitations: Cannot achieve high-gloss surface; sand residue may remain in small holes (needs ultrasonic cleaning).
2. Anodizing (Aluminum Alloy Special Process)
Technical Parameters: Anodizing voltage 10-25V; temperature 15-25℃; film thickness 5-20μm; surface roughness Ra 0.8-3.2μm.
Applicable Materials: Aluminum alloy (6061, 7075, AlSi10Mg) and its composites.
Core Application: Automotive interior/exterior parts, new-energy battery casings, consumer electronics shells; color customization (black, silver, red).
Advantages: Excellent corrosion resistance and wear resistance; customizable color; lightweight (no additional weight gain).
Limitations: Only applicable to aluminum alloy; film is brittle (avoid violent impact); cannot be used for high-temperature environments (>200℃).
3. PVD Coating (Physical Vapor Deposition)
Technical Parameters: Coating thickness 0.5-5μm; hardness 800-2000HV; temperature 150-300℃; surface roughness Ra ≤0.8μm.
Applicable Materials: Stainless steel, titanium alloy, aluminum alloy, die-cast zinc alloy.
Core Application: High-end automotive parts (gear, bearing), medical implants, precision electronic components; requires high wear resistance and decorative effect.
Advantages: Ultra-high wear resistance and corrosion resistance; thin coating (no dimensional impact); environmentally friendly (no harmful substances).
Limitations: High cost; small batch processing efficiency is low; not suitable for large-size parts.
4. Passivation
Technical Parameters: Passivation solution (chromate-free for environmental protection); temperature 20-40℃; processing time 5-15min; corrosion resistance ≥48h (salt spray test).
Applicable Materials: Stainless steel (316L, 17-4PH), titanium alloy, copper alloy.
Core Application: Medical implants, new-energy components, food-grade equipment; requires corrosion resistance without changing part dimensions.
Advantages: Low cost, fast processing; no dimensional change; environmentally friendly (chromate-free passivation complies with RoHS standards).
Limitations: No obvious improvement in appearance; cannot enhance wear resistance.
5. Electroplating
Technical Parameters: Plating layer (nickel, chrome, copper, gold); thickness 1-10μm; surface roughness Ra ≤0.4μm; adhesion (cross-cut test ≥4B).
Applicable Materials: Stainless steel, copper alloy, die-cast zinc alloy, iron-based materials.
Core Application: Decorative parts (automotive logos, electronic connectors), conductive parts, corrosion-resistant components.
Advantages: High-gloss decorative effect; good electrical conductivity; customizable plating layer thickness.
Limitations: Environmental pollution (needs wastewater treatment); plating layer may peel off if pre-treatment is improper.
Quick Selection Guide:
① Oxide layer removal/pre-treatment: Sandblasting;
② Aluminum alloy color customization: Anodizing;
③ High wear resistance/high-end decoration: PVD coating;
④ Medical/stainless steel corrosion resistance: Passivation;
⑤ Decorative/conductive requirements: Electroplating.
Our technical team provides customized metal surface finishing solutions based on material and part requirements.
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Email: selina@marigold-rapid.com
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