The latest method for inspecting the cleanliness of metal surfaces through electroplating of electric heating tubes - Spray pattern method

The latest method for inspecting the cleanliness of metal surfaces through electroplating of electric heating tubes - Spray pattern method

3 Painting method

Drop the degreaser onto the metal surface and evaporate to dryness. If there are no traces, the surface metal surface is clean. If a circular ring appears, it indicates the presence of oil stains.

4 Moisturizing method

A clean metal surface is hydrophilic, so it can be completely wetted by water. When the metal surface contains oil stains, there will be a water cut area that is not wetted by water. Based on the principle of hydrophilicity, in addition to the most simple and commonly used exhalation method and atomizer spray method, there are several detection methods as follows. Due to the fact that the oxide film of metals is also hydrophilic, most of these methods cannot detect whether the oxide film on the metal surface has been removed.

4.1 Spray pattern method

Spray distilled water containing 0.1% dye onto the wetted metal surface using a spray gun and observe the pattern of the spray surface. Places with oil stains will not show dye color as they are not soaked in water. The operating conditions of the spray gun are: air pressure 5.9 × 10-4～9.8 × 10-4Pa, distance 60cm, time 30-50s.

4.2 Water cut-off method

Immerse the sample in water, then remove it from the water surface and tilt it 45 ° to observe if there are any water droplets or areas without water on the surface. If there are any, it indicates the presence of oil stains on the metal surface.

4.3 Mercury drop method

This method is particularly suitable for detecting oil stains and oxide films on metal surfaces. When mercury droplets fall on a metal surface, they will spread out in a clean place and form a small ball at the oxide film and oil stains. Mercury is highly toxic and should be used with caution.

www.superbheater.com