What Are The Functions of The Passivation Treatment for Trapezoidal Screws?

The main functions of trapezoidal screw passivation are as follows:

1. Enhance corrosion resistance

Passivation forms a dense oxide film on the surface of trapezoidal screws (such as the Cr₂O₃ film on the surface of stainless steel), effectively isolating the metal substrate from the external corrosive media (such as water, oxygen, acids, and bases), reducing or preventing electrochemical reactions of the metal, thereby significantly improving the corrosion resistance of the screws and extending their service life. This effect is particularly pronounced in humid, high-salt, or corrosive environments.

2. Maintain dimensional accuracy

The passivation film is extremely thin (usually 5-15 nanometers) and almost does not change the nominal size and thread accuracy of the screws. For trapezoidal screws that require high precision transmission, passivation treatment does not cause assembly jams or affect transmission accuracy, making it an important means to maintain dimensional stability in precision mechanical applications.

3. Reduce surface contamination and wear

The passivation film makes the screw surface smoother, reducing surface roughness and minor unevenness, lowering friction resistance when in contact with the nut, and reducing the adhesion of dust, oil, and other contaminants on the surface, indirectly helping to reduce wear and improving transmission efficiency.

4. Meet industry compliance requirements

In industries with strict requirements for hygiene and environmental protection, such as food, medicine, and electronics, passivation treatment (especially non-chrome passivation) ensures that the screw surface is free of oil stains and heavy metal residues, complying with relevant regulations and standards (such as FDA, GMP, RoHS, etc.), avoiding product quality issues or compliance risks due to surface contamination or excessive harmful substances.

It should be noted that passivation is not a universal protection method. In strong acid, strong alkali environments, or under long-term high-frequency friction, the passivation film may be damaged. At this time, it is necessary to combine other protective measures (such as coating anti-rust oil, selecting corrosion-resistant materials, etc.) to ensure the performance of the screws.

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