When you are buying fasteners, one of the things you will usually need to think about is the type of plating used for them, and whether or not it will suit your needs. Plating is a process where a thin film of another metal is placed on the surface of the fastener. The main goal […]

When you are buying fasteners, one of the things you will usually need to think about is the type of plating used for them, and whether or not it will suit your needs. Plating is a process where a thin film of another metal is placed on the surface of the fastener. The main goal of doing this is to ensure that the fastener ends up getting anti-corrosive properties. In order to do this, the metal used to coat the fastener needs to have such chemical properties.
In addition to that, the other main reason to get such a fastener is for aesthetic reasons. Some metals used to make fasteners tend to change color with time due to oxidation. By having them coated with a different metal that resists this, you can ensure that they last longer without losing their luster.
There are different ways in which this type of plating can be done, and each has its own pros and cons. Some of the most important of these include:

Hot dip galvanizing
Galvanizing is a process by which a layer of zinc is added to the surface of the fastener in order to reduce the chances of any corrosion on the fastener. This is one of the simplest methods of plating metals, since it simply means dipping them into a vat of molten zinc. As a result, a layer of zinc that is around 80 to 100 microns think is formed on the surface of the fastener. This method of plating is not recommended for when thread tolerances are strict, since some of the zinc may end up clogging some of the threads. In addition to that, it’s also not a preferred method to use when a strong fastener has to be obtained.

 
Electrolytic plating
The other common method of plating is through the use of electrolysis. Due to the fact that this is one of the cheapest methods of going about it, it has become one of the most commonly used. To use this method of plating, the fastener, such as a grade 8 steel hex tap bolt, is attached to an anode, and then placed in a solution of the metal. This way, the positively charged ions of the metal will detach from the solution, and then be attached to the fastener which acts as the cathode.
Mechanical plating
In this method of plating, the fastener is blasted with a thin film of the metal that is supposed to be used to plate the fastener. This is usually combined with a carrier that will enable the metal to attach to the fastener with ease. This is a method of plating most useful for fasteners that are likely to suffer from hydrogen embrittlement.
There are many other ways you can plate fasteners such as grade 5 steel hex head cap screws, but the above are the most common. All in all, using plated fasteners is always recommended since they are more resistant to corrosion, which means that you are less likely to have to witness them failing.

About the Author

Larry Melone
By Larry Melone
President

Started my career in the fastener world in 1969 at, Parker Kalon Corp. a NJ based screw manufacturer located in Clifton, NJ working in inventory control, scheduling secondary production and concluding there in purchasing. In 1971 I accepted a sales position at Star Stainless Screw Co., Totowa, NJ working in inside sales and later as an outside salesman, having a successful career at Star I had the desire with a friend to start our own fastener distribution company in 1980 named: Divspec, Kenilworth, NJ. This was a successful adventure but ended in 1985 with me starting Melfast in August 1985 and have stayed competitive and successful to date. Melfast serves the OEM market with approximately 400 accounts nationally.

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