Why do hot-dip galvanized fan flanges need to be punched first and then galvanized?

The hot-dip galvanized fan flange adopts the process of punching first and then galvanizing, mainly to ensure the integrity of the flange structure, improve the quality of the galvanized layer, optimize sealing, control costs, and improve production efficiency. The specific analysis is as follows:

1. Ensure the integrity of the flange structure

Punching process requirements: The bolt holes and connection parts of the flange need to be accurately formed. If galvanized first and punched later, the high-temperature zinc layer may make the steel brittle, causing edge cracking or deformation during punching, affecting the mechanical performance and sealing of the flange.

Advantage of first punching: Punching is completed before the steel is galvanized, which can avoid the influence of zinc layer on the punching process, ensure the accuracy of hole position and edge quality, and meet the requirements of high-strength and precision connection for fan flanges.

2. Improve the quality of galvanized layer

Uniformity of galvanized layer: For hot-dip galvanizing, the flange needs to be immersed in a molten zinc solution at around 500 ℃. If the flange has been punched, the zinc solution may not be able to evenly cover the inner wall or edge of the hole, resulting in local zinc coating being too thin or missing, which reduces the anti-corrosion performance.

Punching first and then galvanizing: Ensure that the zinc solution can fully penetrate all surfaces of the flange, including the inner walls of the holes, forming a complete and uniform galvanized layer, and extending the service life of the flange.

3. Optimize sealing and connection reliability

Sealing surface protection: The sealing surface of the fan flange should be flat and defect free. Punching first can avoid the accumulation of zinc liquid on the sealing surface during the galvanizing process, which may cause poor sealing or leakage.

Bolt connection stability: Accurate punching can ensure a tight fit between the bolt hole and the gasket, improve connection reliability, and reduce vibration and loosening risks during operation.