At SYSTEEL VINA, product quality is paramount. Our stringent quality control processes ensure that each coated steel sheet meets the highest standards before reaching our customers. Below are the detailed steps in this process:

1. Overall Visual Inspection

  • Method: Inspect the surface appearance of the steel sheet.
  • Result: Ensure there are no deformations, dents, scratches, black or white streaks, rust, and that the paint surface is glossy and smooth.
  • Standard: SY STANDARD.

2. Dimensional Inspection

  • Method: Measure thickness and width using micrometers, calipers, and tape measures.
  • Result: Thickness includes raw material thickness (8%) and coating thickness, with width in the range of 0/+5.
  • Standard: SY STANDARD.

3. Flatness Inspection

  • Method: Use measuring tools to check the height of the expansion and wavelength ratio.
  • Result: Product meets requirements if H ≤ 6mm, Z ≤ 1% (Z = H/L * 100).
  • Standard: SY STANDARD.

4. Gloss and Color Inspection

Gloss:

  • Method: Measure 60-degree gloss with a gloss meter.
  • Result: Compare with a limit sample (±5%).
  • Standard: ASTM D523-89.

Color Difference:

  • Method: Measure color difference with a colorimeter.
  • Result: Compare with a limit sample (????E < 1.0).
  • Standard: ASTM D2244-93.

5. Coating Thickness Inspection

  • Method: Measure with a coating thickness gauge (Elcometer 355).
  • Result: Ensure it meets BOM requirements (tolerance ±5μm).
  • Standard: ASTM D4138-94c.

6. Pencil Hardness Test

  • Method: Use a HB pencil (Mitsubishi UNI) at a 45-degree angle to draw five lines on the surface with a 750g force, then erase horizontally.
  • Result: If more than three lines show indents or scratches, the product fails.
  • Standard: ASTM D3362-22.

7. Impact Test

  • Method: Drop a 1000g steel ball from a height of 500mm onto the back surface of the sheet.
  • Result: The coating should not peel off.
  • Standard: ASTM D2794.

8. Cross Cut Test (Erichsen)

  • Method: Cut horizontally and vertically to create 1mm² x 100 squares, then test coating adhesion by applying and pulling off tape.
  • Result: The coating should not peel off.
  • Standard: ASTM D3359 and ASTM E643.

9. T-Bend Test

  • Method: Bend the steel sheet to a 180-degree angle, apply and pull off tape.
  • Result: The coating should not peel off.
  • Standard: ASTM D522-93a.

10. MEK Rub Test

  • Method: Apply Methyl Ethyl Ketone to the painted surface and rub with gloves 50 times.
  • Result: If the raw material is exposed, the product fails.
  • Standard: ASTM D5402-93.

11. Alkaline and Acid Resistance Test

Resistance to Alkalies:

  • Method: Soak the sample in 5% NaOH solution at room temperature for 48 hours.
  • Result: The surface should not peel, crack, blister, warp, or change color.
  • Standard: SY STANDARD.

Resistance to Acids:

  • Method: Soak the sample in 5% CH3COOH solution at room temperature for 48 hours.
  • Result: The surface should not peel, crack, blister, or warp.
  • Standard: ASTM D543-06.

12. Boiling Water Resistance Test

  • Method: Soak the sample in boiling water (90°C or higher) for 1 hour.
  • Result: The surface should not peel, crack, blister, warp, or change color.
  • Standard: SY STANDARD.

13. Salt Spray Test

For Home Appliances:

  • Method: Score an "X" on the painted surface, spray with 5% NaCl in an SST machine for 240 hours.
  • Result: The surface should not blister or rust.
  • Standard: JIS Z2371.

For Construction:

  • Method: Continuously spray with 5% NaCl in an SST machine for 500 hours.
  • Result: The surface should not blister or rust.
  • Standard: JIS Z2371.

14. Heat Resistance Test

  • Method: Place the sample in a chamber at 70°C ± 2 for 1 hour.
  • Result: The surface should not peel, crack, blister, warp, or change color.
  • Standard: SY STANDARD.

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Conclusion

This rigorous inspection process ensures that SYSTEEL VINA delivers high-quality products that meet customer requirements and international standards. Adherence to ASTM and JIS standards not only enhances SYSTEEL VINA's reputation but also contributes to the sustainable development of Vietnam's steel industry. These stringent quality control procedures enable SYSTEEL VINA to be a reliable partner, providing the best-coated steel products to customers worldwide.