Galvanising @ JPK – Whats involved…
Galvanising is a specialist process so JPK engage the services of professional Galvanising companies to ensure quality at each stage of the process.
so whats involved in the process
The galvanising process involves several key stages to ensure that the steel or iron is properly coated with a protective layer of zinc. Here’s a detailed overview of each stage:
1. Pre-Inspection
- Purpose: To check for surface conditions, cleanliness, and suitability for galvanising.
- Details: The steel or iron is inspected for defects, sharp edges, and contaminants. Any issues found are noted and rectified before proceeding to the next stage.
2. Degreasing/Caustic Cleaning
- Purpose: To remove grease, oil, and other organic residues from the surface.
- Details: The material is immersed in a hot, caustic solution (typically sodium hydroxide) to clean away contaminants like dirt and oil.
3. Rinsing
- Purpose: To remove any caustic solution residues.
- Details: The material is thoroughly rinsed with water to ensure no caustic solution remains on the surface.
4. Pickling/Acid Cleaning
- Purpose: To remove mill scale, rust, and oxides from the surface.
- Details: The material is immersed in an acidic solution (usually hydrochloric or sulfuric acid) to etch the steel surface and remove oxidation layers.
5. Rinsing
- Purpose: To remove any acid residues from the pickling stage.
- Details: The material is rinsed with water to prevent contamination of subsequent stages.
6. Fluxing
- Purpose: To prevent oxidation before the galvanizing process and to promote adhesion of zinc.
- Details: The material is dipped in a flux solution (typically zinc ammonium chloride) or sprayed with flux. This step prepares the surface for galvanising by preventing oxidation and improving zinc bonding.
7. Drying
- Purpose: To ensure the material is free of moisture before galvanising.
- Details: The material is allowed to air dry or is dried in an oven. This prevents any reaction of water with molten zinc, which can cause defects.
8. Galvanizing (Hot-Dip Process)
- Purpose: To apply a protective zinc coating.
- Details: The material is immersed in a bath of molten zinc, heated to around 450°C (842°F). The zinc bonds with the steel, forming a series of zinc-iron alloy layers and an outer zinc layer.
9. Cooling/Quenching
- Purpose: To cool the material and solidify the zinc coating.
- Details: After being removed from the zinc bath, the material is cooled by air or quenched in a water bath. Some galvanisers may add passivation chemicals during quenching to further protect the coating.
10. Inspection and Finishing
- Purpose: To check the quality of the coating and make any necessary finishing touches.
- Details: The coating thickness is measured to ensure compliance with standards. Visual inspection is conducted to check for defects, uniformity, and overall appearance. Excess zinc is removed if necessary.
- Edges: Some suppliers engage in a process where the remove any rough edges which may have appeared through the galvanising process.
11. Final Inspection and Packaging
- Purpose: To ensure the material is ready for dispatch and meets all specifications.
- Details: The final inspection ensures that the galvanised coating meets customer specifications and industry standards. The material is then packed and prepared for delivery.
JPK rely on our suppliers for this process and these relationships are paramount to our continued success.