Fig. 6 shows a mild steel garden gate that needs to be protected from corrosion. The metal has been selected for its specific properties that make it suitab...
Question 1 Report
Fig. 6 shows a mild steel garden gate that needs to be protected from corrosion. The metal has been selected for its specific properties that make it suitable for this application. Different metals have different properties that affect how they can be worked and used. The choice of metal depends on the functional requirements of the product.
It can be fixed if it breaks. It is held in place. All the bits are smooth.
The beech can be shaped using cutting or planing.
(a) Name one suitable finish to protect the gate from corrosion. [1]
(b) Describe the preparation steps needed before the finish is applied to the gate. [2]
Answer Details
(a) A suitable finish to protect the mild steel gate from corrosion is galvanising (hot-dip galvanising) [1]. Other acceptable finishes include powder coating, paint, or zinc plating. Each of these creates a barrier between the steel surface and moisture in the air, preventing the oxidation reaction (rusting) that would otherwise degrade the metal.
(b) The preparation steps before applying the finish are:
- Remove any existing rust or mill scale using a wire brush, sandpaper, or an angle grinder with a flap disc [1]. Rust is loose, flaky iron oxide that prevents the finish from adhering properly; if left in place, it continues to spread underneath the coating.
- Clean the surface to remove grease, oil, and dirt using a degreaser or solvent wipe [1]. Contaminants on the metal surface prevent the finish from bonding, leading to peeling and early failure of the protective coating.
Applying a primer or undercoat before the top coat, and filling any dents or imperfections with a suitable filler, are also valid preparation steps.
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