Posted by in Manufacturing Capability, on March 1, 2017

Coatings

Depending on the use your fasteners and forgings you may require them to be coated. Coatings protect metal from corrosion and rust when they’re exposed to the atmosphere, freshwater or seawater.

Coatings can also serve aesthetic purposes, such as when the head of the bolts or parts of the fastener will be visible when in place. In this case coatings can help the bolts and fasteners to blend in with or complement the existing structure for a clean finish.

Types of coatings are mechanical galvanising and electroplating. Both processes preserve the steel by acting as a sacrificial or cathodic protection. Mechanical galvanising is performed at room-temperature without electricity, and components go through a mechanical process called ‘rumbling’. Electroplating requires the use of a current to make the coating adhere to the steel.

Zinc, as it’s more reactive than steel, is used in both types of coatings, and there are three options: black, clear (also known as blue) and gold zinc. Gold is the strongest at resisting corrosion.

We also provide hot dipped galvanizing, a process of coating iron and steel in a bath of molten zinc at around 450 C. When exposed to the atmosphere, the pure zinc reacts with oxygen to form zinc oxide which further reacts with carbon dioxide to form zinc carbonate, a usually dull, grey, strong material that protects the steel underneath from further corrosion.

PTFE coatings, or Polytetrafluoroethylene are non-stick fluoropolymer coatings that use a two-coat (primer/topcoat) system. This coating is normally used where a dry lubricant or low friction, or corrosion resistant coating is necessary.

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