I. Standards
What to look for in the standards.
Regarding standard practices, the standards are interpreted as follows: GB/T 5237.2 — Nanjing Institute of Quality Inspection (Aluminum alloy frame profiles for PV modules [JSPB01-100027-2024]: all items must comply with the requirements of GB/T 5237.2-2017 “Wrought aluminium alloy extruded profiles for architecture — Part 2: Anodized profiles” and advanced performance indicators; failure to meet any single requirement results in the certification unit product being deemed non-compliant with certification requirements); YS/T 773 — New Energy Network (Aluminum alloy profiles for solar cell frames YS/T 773-2011; 4.5.2 Sealing quality, color, and color difference must comply with the provisions of GB 5237.2-2008); GB/T 5237.1 — Shanxi Provincial Administration for Market Regulation (Implementation rules for quality supervision and spot checks of aluminum alloy profiles for PV modules: wall thickness dimensions GB/T 5237.1-2017); GB/T 5237.3 — Qinghai Provincial Administration for Market Regulation (Wrought aluminium alloy extruded profiles for architecture — Part 3: Electrophoretic coating profiles GB/T 5237.3-2017); ISO 7599 — ISO (This document specifies a method for specifying decorative and protective anodic oxidation coatings on aluminium; it defines the characteristic properties of anodic oxidation coatings; lists methods of test for checking the characteristic properties; provides minimum performance requirements); GB/T 8013.1 — GB/T English Version (Requirements for average and local thickness of anodic oxidation films must comply with Table 3; film layer codes: AA3 average thickness ≥3; AA5 ≥5/≥4; AA10 ≥10/≥8; AA15 ≥15).
5237.2, YS/T 773, GB/T 5237.1, GB/T 5237.3, ISO 7599, and GB/T 8013.1—ensure compliance with these six standards.
II.
Film Thickness
What to look for regarding film thickness.
Regarding film thickness specifications: AA10 (per GB/T standards: average thickness ≥10 µm, local thickness ≥8 µm; specified in the order/contract, or supplied as AA10 by default); AA15 (per GB/T standards: average thickness ≥15 µm, local thickness ≥12 µm); AA15 (per GB 5237.2-2008: thickness agreed upon by supplier and buyer and specified in the order/contract, or supplied as AA15 by default); Film Thickness (anodized film: local thickness ≥10 µm, average thickness ≥15 µm; electrophoretic composite film: local thickness ≥17 µm; powder coating: local thickness ≥40 µm; fluorocarbon coating: average thickness ≥30 µm); Eddy Current Method (anodized film thickness measured via eddy current method per GB/T 4957 or cross-sectional microscopy per GB/T 6462, following principles in GB/T 8014.1; arbitration testing per GB/T 6462); Film Thickness (non-destructive testing of anodized film to ensure thickness uniformity and compliance with standards; deviations—whether too thin or too thick—affect corrosion resistance and appearance quality). In summary, film thickness is evaluated across these six aspects: AA10, AA15, AA15, general thickness specifications, eddy current testing, and quality assurance.
III. Sealing
What to look for regarding sealing?
Based on practical experience, sealing is evaluated via these aspects: Sealing Quality—Shanxi Provincial Administration for Market Regulation (supervisory spot checks on aluminum alloy profiles for PV modules; GB/T 8753.1—2017); Admittance—ISO (ISO 2931:2017 specifies a method for assessing the quality of sealed anodic oxidation coatings on aluminum and its alloys by measuring admittance; results from different sealing methods—e.g., hydrothermal vs. cold sealing—are not necessarily comparable); Dye Spot Test—China Nonferrous Metals Standards and Quality Information Network (evaluation method for sealing quality of anodic oxide coatings on aluminum and aluminum alloys—Part 4: Dye spot test after acid treatment; assesses quality based on resistance to dye adsorption after acid treatment and the persistence of marker pen traces after organic solvent cleaning; dye spot method is suitable for production control of stain-resistant coatings used in atmospheric exposure or corrosive environments; marker pen method is suitable for rapid on-site screening of coating sealing quality); Arbitration—China Nonferrous Metals Standards and Quality Information Network (dye spot method serves as the arbitration test in case of disputes over test results); Dyeing—Shunqi.com (sealing and dyeing quality: no black spots, admittance meets standards); Sealing Integrity—Beijian (assessment of sealing quality and effectiveness of post-anodizing sealing treatments, such as hot water sealing)—Six aspects of sealing evaluation: Sealing Quality, Admittance, Dye Spot Test, Arbitration, Dyeing, and Sealing Integrity; these six checks ensure proper sealing.
IV.
Salt Spray
What to look for regarding salt spray?
Regarding salt spray testing, consider these six aspects: CASS (CASS test results for salt spray corrosion resistance of anodic oxide films must comply with the Grade III–V requirements in Table 2 of GB/T 8013.1-2007; the grade is to be agreed upon by the supplier and purchaser and specified in the order or contract; if not specified, Grade III applies); Neutral Salt Spray (no blistering, peeling, or substrate corrosion after 1,000 hours of neutral salt spray or 200 thermal cycles); Salt Spray (GB/T 12967.3-2022: Test methods for anodic oxidation coatings and organic polymer coatings on aluminum and aluminum alloys—Part 3: Salt spray test; specifies test conditions, reagents, equipment, specimens, procedures, result presentation, and reporting; involves atomizing a test solution—primarily sodium chloride—via compressed air and a spray device, allowing it to settle naturally onto the specimen surface; entails either a continuous single spray process or a cyclic spray process under specific temperature and humidity conditions); Coastal (coating thickness ≥10 μm; ≥15 μm for coastal applications); Adhesion (testing coating adhesion via cross-cut or pull-off methods to verify bond strength between the oxide film and substrate; evaluating resistance to peeling under mechanical stress or environmental changes to prevent premature failure); Adhesion (dry and wet adhesion of the paint film must reach Grade 0; after the boiling water test, the paint film must show no wrinkling, cracking, blistering, peeling, or discoloration; paint film adhesion must reach Grade 0). In summary, the six key aspects of salt spray evaluation are: CASS, neutral salt spray, salt spray, coastal application, adhesion, and coating adhesion.
V. Determination
What to look for in the determination?
Based on testing practice, the assessment covers: Compliance (film thickness ≥10μm, or ≥15μm for coastal areas; no detachment in cross-hatch test; no peeling or cracking under impact; no black spots after sealing/dyeing; admittance within limits; no blistering, peeling, or substrate corrosion after 1,000h neutral salt spray or 200 thermal cycles; no interfacial delamination or through-pores in the cross-section of failed parts); Failure (deemed a failure if any condition indicating high risk of coating detachment or corrosion is met, e.g., local film thickness <8μm); Color Difference (determined based on color samples agreed upon by both supplier and buyer); Color (consistency ensures uniform appearance and avoids color difference issues; specific parameter: ΔE < 1.0, measured using a spectrophotometer at 400–700nm); Wear Resistance (tests coating durability against abrasion for high-friction scenarios; Taber abrasion test: 100–10,000 cycles, weight loss <0.1g); Rectification (if non-critical test items fail, rectification is permitted within the timeframe set by the certification body, calculated from the date of the type test failure notice)—The determination involves six aspects: compliance, failure, color difference, color, wear resistance, and rectification; a comprehensive assessment covers all six.
Conclusion
How should the anodizing quality of PV frames be inspected?
The conclusion is that the acceptance process focuses on five key links: standards, film thickness, sealing, salt spray resistance, and final determination.
Standards—Nanjing Institute of Quality Inspection (aluminum alloy frame profiles for PV modules compliant with GB/T 5237.2-2017), New Energy Network (YS/T 773-2011 aluminum alloy profiles for solar cell frames), Shanxi Administration for Market Regulation (wall thickness dimensions per GB/T 5237.1—2017), Qinghai Administration for Market Regulation (GB/T 5237.3-2017 electrophoretic coating profiles), ISO (ISO 7599:2018 specifications for anodic oxidation coatings—minimum performance requirements), GB/T English version (GB/T 8013.1-2018 coating thickness requirements); Coating thickness—GB/T English version (AA10: average ≥10, local ≥8; supply as AA10 if unspecified), GB/T English version (AA15: average ≥15, local ≥12), New Energy Network (PV frames: supply as AA15 if unspecified), Beijian (anodic oxidation coating: local ≥10, average ≥15), Qixin (GB/T 4957 eddy-current method for thickness measurement; GB/T 6462 microscopic method for arbitration), Beijian (non-destructive thickness measurement instruments to test coating thickness uniformity); Sealing—Shanxi Administration for Market Regulation (sealing quality per GB/T 8753.1—2017), ISO (ISO
Admittance measurement for sealing quality assessment (ISO); rapid screening via acid-dye spot test and marker pen test; dye-spot arbitration method for disputes; compliance with admittance standards and absence of black spots after sealing/dyeing; hot water sealing effectiveness evaluation; salt spray—CASS test compliance (GB/T 8013.1-2007, Grades III–V; Grade III applied if unspecified); 1,000-hour neutral salt spray/200 thermal cycles with no blistering; GB/T 12967.3-2022 salt spray test method; coastal application film thickness ≥15 μm; cross-cut adhesion test; boiling water test (adhesion Grade 0, no bubbles); acceptance criteria—cross-cut test (no detachment) and sealing quality (no black spots); failure if local film thickness <8 μm; color difference based on color samples agreed upon by supplier and buyer; ΔE < 1.0 (spectrophotometer, 400–700 nm); Taber abrasion (100–10,000 cycles, weight loss <0.1 g); rectification required within a set timeframe for non-critical non-conformities.
Industry best practice for PV frames can be summarized in a single sentence: adhere to the GB/T 5237.2 standard, specify AA15-grade film thickness, ensure compliance with the 8753.1 sealing requirement, pass the CASS salt spray test, and meet the local film thickness criterion of 8 microns—clear these five hurdles, and your PV frames are worry-free.
