Hot Dip Spinning Galvanizing

They are the same process. Hot dip galvanizing means immersing cleaned steel in a bath of molten zinc at around 450 °C, where the zinc reacts with the steel to form a series of zinc-iron alloy layers that are metallurgically bonded to the substrate rather than sitting on top of it. Spin galvanizing — also called centrifuge galvanizing — is that same hot dip process with one extra step for small components.

When bolts, nuts, washers and fittings come out of the kettle, molten zinc pools in threads, recesses and internal profiles. Spinning the basket at high speed the moment it leaves the zinc throws that excess off before it solidifies, so threads still assemble, holes stay clear and coverage stays even across every face. That is why spin galvanizing is the standard route for hardware, while large fabrications, structural steel and long sections are dipped and drained without spinning.

Coating thickness follows the hot dip norms — typically in the 40–85 µm range on fasteners, in line with what SANS 121 / ISO 1461 expects for components of that size — and because the layer is thick and alloy-bonded, service life outdoors is routinely measured in decades rather than years. The coating is sacrificial too: exposed steel at a cut edge or scratch is still protected by the surrounding zinc.

Suitable substrates are carbon and low-alloy steels and cast iron. If your parts are too large for our spinning baskets, are high-strength fasteners where hydrogen embrittlement is a concern, or need a tighter dimensional tolerance than a hot dip layer allows, tell us — zinc thermal diffusion or zinc electroplating is often the better call, and we will say so before you commit.