Zinc Plating

Why choose zinc plating?

  • Excellent corrosion resistance
  • Sacrificial
  • Good base for paint or powder coating
  • Cost effective
  • 5 to 25μm coating thickness
  • RoHS compliant options

Specifications that we offer:

Why choose Metal Finishings Ltd?

  • Fast turnaround - as short as 24 hours
  • High quality
  • ISO 9001 and AS 9100 certified
  • Nationwide service with our trusted courier
  • No-obligation quotations
  • Free certificates of conformity

Zinc Plating Not Currently Offered

We are not currently offering zinc plating but we do plan to reinstate this service later in the year, along with several other new surface treatments. If you would like to be kept informed of developments in our new facility, please join our mailing list, or contact us with your specific query.

What is Zinc Plating?

Zinc plating involves zinc metal being electrodeposited on to components. Zinc plating is passivated to give it corrosion resistance and the zinc plating protects the underlying material further by being sacrificial. Zinc electroplating is a form of electrochemical galvanization. The passivation on zinc plating determines its final colour - we can offer clear (blue tinted, trivalent), colour (yellow iridescent, hexavalent) or black (black, trivalent). Thicknesses of 5µm, 8µm, 12µm and 25µm are common, but other thickness are available on request. We offer bright zinc plating on components made of steel (up to 1000 MPa ultimate tensile strength), copper, brass and bronze.

Specifications Offered

We can work to many other specifications, but the above are our most popular. Please contact us with your requirements.

Information for Designers

Thickness and Growth

Zinc Plating is deposited on the surface of the component. So the growth per surface will be equal to the thickness per surface. Thicknesses for zinc plating are generally specified as minima (ISO 2081 and ASTM B633), although control within a range is possible. We have written some guidance for zinc plating thickness.

Sacrificial Anode

A coating of zinc on steel acts as a sacrificial anode because of its position in the galvanic series. This is very useful because even if the coating is scratched or damaged, the zinc will provide protection to the base metal by sacrificing iteself.

Base Material Condition

The base material is very important to the quality of the plating. Best results will be obtained by using clean steel (as opposed to black steel). It is recommended that you ensure that material is not porous or pitted, because these will be corrosion sites despite the zinc plating. A common problem is when people use bar without mechanically abrading/machining the surface. ASTM B663-13 states:

Defects in the surface of the basis metal, such as scratches, porosity, pits, inclusions, cracks, roll marks, and die marks, may adversely affect the appearance and performance of coatings applied thereto despite the observance of the best electroplating practices.

Tensile Strength of Base Metal

Components with a tensile strength of over 1000 MPa are liable to hydrogen embrittlement and require de-embrittlement and stress relief. We do not offer this service and accordingly do not treat parts with a tensile strength in excess of 1000 MPa. Please do not send us parts that require the above.

Throwing

This is not a concern for the majority of parts. The geometry of parts may make it difficult for the zinc to "throw" into certain areas (usually insides of tubes and the corners of deep boxes). For situations like this we can usually have an internal anode manufactured (for all over coverage) or if that is not economic or not possible, we can dip the part in a corrosion inhibitor that helps to protect the bare areas.

Parts that have been zinc plated and colour passivated.
Parts that have been zinc plated and colour passivated.