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How to solve surface roughness issues during steel grating production?

Time:2021-11-23

Hot-Dip Galvanized Steel Grating: Surface Roughness & Solutions

 

Steel grating is often referred to as Hot-Dip Galvanized Grating. This coating is obtained by immersing steel components into a molten zinc bath. In recent years, with the development of high-voltage power transmission, transportation, and communications, the demand for steel component protection has increased, leading to higher demand for hot-dip galvanizing.

 

Galvanized steel grating is widely used in alloys, building materials, power plants, boilers, shipbuilding, chemical industries, general industrial plants, and municipal construction. Applications include platforms, handrails, flooring, road surfaces, overhead tower platforms, trench covers, railway bridge side covers, parking lots, schools, factories, playgrounds, villa fencing, window guards, balcony railings, and highway/railway barriers. Given this wide usage, how do we solve the issue of surface roughness during production?

 

Reasons of Roughness at the Tail End

 

The rough surface at the tail end of hot-dip galvanized steel grating typically occurs in processes where external blowing is performed before internal blowing. This roughness is short but thick and severe, often appearing as droplet-shaped stalactites.

 

This phenomenon primarily occurs because the grating is held at an incline during internal steam blowing. After blowing, the un-solidified zinc liquid continues to flow outward. Some zinc flows away, while some forms droplet-shaped stalactites around the tube/punching holes. As the temperature decreases, it solidifies.

 

The main reason is that the steam jet, when suddenly exiting the hole, diffuses outward. This diffusion forces the molten zinc inside the grating to splash and flow. Due to the viscosity of the zinc liquid, part of it flows down along the outer edge of the hole opening. Upon cooling, it solidifies into a short, thick zinc run-down (zinc dross).

 

Solution

 

To resolve this issue, the following adjustments should be implemented:

 

Eliminate the Incline: Remove the tilting angle during the blowing process.

 

Rotation on Cooling Bed: Elevate the tail end of the grating and rotate it while it moves along the cooling bed to allow the zinc to solidify evenly.

 

Additional Blowing Facilities: Increase the blowing equipment around the peripheral holes at the tail end to ensure a smoother finish.