A process where zinc is physically applied to metal substrates, usually steel. Mechanical plating provides a robust surface resistant to corrosion. It utilizes impact energy to cold weld fine metal particles to the substrate. The system uses an open-ended barrel with glass beads as the impact media. It provides a smooth, semi-bright finish with superior corrosion protection.
Advantages of mechanical galvanizing:
Eliminate re-tapping of nuts: In hot-dip galvanizing, threads must be cut or chased after galvanizing, robbing them of protection and requiring extra expense. Mechanical Galvanizing produces parts that are ready to use without any further processing steps. In heavy thickness application such as Class 50, nuts must be tapped prior to coating
No hydrogen embrittlement: Because Mechanical Galvanizing is an extension of mechanical plating technology; it does not produce hydrogen embrittlement, making it ideal for high strength fasteners. Special cleaning procedures may be required to minimize the possibility of hydrogen formation prior to coating.
Below is the most common specification for mechanical galvanizing.
ASTM B 695
Class Minimum Thickness, µm
Type I – As coated, without supplementary treatment
Type II – With colored chromate conversion treatment