To determine whether the laminated board needs to be replaced, it is necessary to consider multiple dimensions such as appearance, performance, environment, and economy. The specific criteria are as follows:
1. Critical value of appearance damage
Abnormal membrane layer
Lift up>3mm or bubble area ≥ 5%.
UV induced fading Δ E>3 (color difference is clearly visible to the naked eye).
Cracks penetrate the film layer (especially when the thickness of the metal plate film is less than 40 μ m).
substrate degradation
The corrosion area of the steel plate is greater than 5%.
Aluminum plate oxidation white spots or black spots diffuse.
Solid wood substrate moisture content>15% or cracking>2mm.
2. Performance Failure Criteria
Waterproof: If water leakage or seepage marks continue to appear, it is recommended to conduct a water splashing test with testing tools (contact angle<90 °).
Flexural strength: ＜ 5MPa, it is recommended to use a three-point bending tester for testing.
Thermal insulation performance: thermal conductivity>0.15W/m · K, it is recommended to use a thermal flow meter for testing.
Adhesive force: Peel strength<0.8N/mm, it is recommended to use a tensile tester (90 ° peel method) for testing.
Note: After more than 30 cycles of turnover, the damage rate of building templates suddenly increases by 67%, and metal plates need to be replaced if the salt spray test is less than 1000 hours.
3.Environmental adaptability failure
High humidity environment
The Cl ⁻ concentration on the surface of the magnesium plate is greater than 0.1mg/cm ² (the chloride ion test paper turns red).
After 5 years of use in the kitchen/bathroom, the toughness of PVC film decreases by 50%.
Extreme climates
The metal plate did not reserve a 0.5mm expansion joint, resulting in compression deformation.
ASA coating failure in high UV zone (annual fading rate>23%).
4.Economic replacement principle
Maintenance cost>35% of new material price: replace immediately (such as repairing glass magnesium board with halogen return exceeding 120 yuan/㎡).
Local damage to the membrane layer<20%: can be professionally repaired (extending lifespan by 20%).
Industrial plants used for over 10 years: preventive replacement (to avoid structural risks).
5.Emergency signal replacement (immediately stop)
The hanging amount of the ceiling is greater than 1/200 of the span.
The metal plate fasteners are corroded and loose.
Burning of laminated boards releases irritating gases (risk of poor quality PVC film).
Tip: Regularly using an infrared thermal imaging device to detect areas with a temperature difference greater than 2 ℃ can provide a 30% advance warning of failure.
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