Zinc plating or more specifically Zinc electroplating is one of the most popular coatings used for common finishes within industry.
It is a very cost-effective process, and is mostly used to provide a protective coating to metallic substances such as nuts, bolts, brackets, automotive parts, fabrications, precision and many other sheet metal items.
Besides this benefit, the use of zinc also improves the overall appearance of metals, by giving them, a clean look, brightness, and a nice glowing shine.
Advantages Of Zinc Electroplating
The main advantages of zinc electroplating is its cost-effectiveness and ease of application. It can also be used as an undercoat for paints, as it prevents the formation of white rust for a long period of time, and has excellent ductile and adhesive properties.
Visual aesthetics can be improved with the type of passivation used these would normally be a clear blue tinted finish,or sometimes known as silver zinc plating and Yellow iridescent or Yellow zinc plating.
The Zinc coating can be post treated utilising lacquers and varying types of silicate seals further to enhance corrosion value or improve handling properties. More information can be found under our heading post “ Treatments”. For useful technical information regarding the processes and chemicals we currently use see Zinc Corrosion Protection Values
Passivation Of Zinc Electroplating
There are 3 passivation systems used here at our Staffordshire headquarters as a top coat treatment to delay the onset of white corrosion products. These are Clear, Yellow, and Thick film trivalent passivation (Chrome VI replacement).
Generally Clear and yellow are the most prolific passivation systems used within industry due to aesthetics and service condition requirements.
Clear if controlled correctly shall be of a bright finish with silver to blue tint, whilst yellow may appear to be yellow or gold with red and green iridescence, the colours may vary due to temperature conditions and various other factors.
This variation would be classed as normal, however, if a uniform yellow or gold appearance is required then a clear water based lacquer could be used to unify the appearance.
Clear Passivation would normally be used for internal components including electronic metal fabrications and some fasteners etc. Whilst yellow would be commonly used on external parts which may be subject to wet, damp and salt exposure conditions used commonly on agricultural machinery and motor vehicles although many manufacturers are changing to alternatives.
Environmental legislation is dictating what passivation systems can be used .In the past Hexavalent chromium was used to enhance the corrosion value of Zinc plated products. However, over the last few years technological developments in finishing chemistry has allowed the Hexavalent Chrome6 (VI) to gradually be replaced with alternative Chrome 3(III) or Trivalent passivation systems .
There have been many variations in legislation changes , Rohs , WEEE and ELV directives to eventually ban or limit the use of hexavalent compounds. Here at Diamond Metal Finishing (Abb) we offer both processes to give the customer a choice .
However, over the next couple of years it is expected that new legislation will ban the use of the Hexavaent processes altogether.
Please visit our “Zinc corrosion value” table which also gives indications of which processes conform to the Rohs, WEEE and Elv directives together with performance criteria of white and red corrosion expectations.
Why use Diamond Metal Finishing?
Because you need a metal finisher who is reliable and can give you the customer the very best quality available by processing your parts to an unrivalled consistent, uniform, aesthetically pleasing quality, finished right first time to meet the relevant performance criteria.
All of our Zinc plating machinery is fully PLC controlled even down to auto chemical dosing for stable brightness and colour continuity. Add this together with full parts library and traceability inbuilt into our systems to give you full confidence and peace of mind.
Further technical advice is available by using our contact form.