Plating onto Aluminum
It's hard to imagine going through an entire day without seeing, using or coming into contact with an object that is made of aluminum. This soft, lightweight, durable metal can be found in everything from aircraft and vehicle parts and components to food and beverage containers, foil wrap, windows and doors, lighting poles and much more.
Aluminum is also big business: According to the Aluminum Association, aluminum's direct economic impact is greater than $75 billion per year. When considering the impact on suppliers and other related industries that use aluminum — metal finishing companies, for example — the total exceeds $186 billion.
The Need for an Aluminum Electroplating Process
In many manufacturing applications, it is helpful — and in some instances, necessary — to apply an additional coating onto an aluminum part for purposes such as increasing corrosion protection, providing greater wear resistance or enhancing the appearance of a product. Electroplating is a common metal finishing technique that can achieve each of these objectives. This process involves immersing the aluminum workpiece into an electrolytic solution and introducing an electric current to deposit dissolved ions of another metal onto the surface.
An alternative to the aluminum electroplating process is electroless plating, which does not require electricity to deposit the metal ions. Instead, deposition occurs via an autocatalytic reaction.
The Use of Aluminum Alloys in Manufacturing
It is rare to find industrial parts and components made of pure aluminum. Most manufacturers use an aluminum alloy consisting of aluminum as the base material and another metal such as zinc, tin, magnesium or silicon. The additional metal material enhances the properties of the aluminum and makes the part more amenable to electroplating and other metal finishing techniques. Many aircraft parts, for instance, feature an aluminum-magnesium alloy, as it provides the combination of lightweight construction and reduced flammability that meets the stringent manufacturing requirements of the aerospace industry.
There are two primary aluminum alloy classifications: wrought and cast. Wrought aluminum alloys are the most common type used in manufacturing applications for products such as foil, extrusions and rolled plate. Cast alloys offer less tensile strength than their wrought counterparts, but their lower melting point makes them a more cost-effective solution.
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Plating Onto Aluminum Alloys
The widespread use of aluminum alloys has led to the development of various electroplating and electroless plating techniques that are compatible with these materials. In addition to aerospace, plating on aluminum alloys meets the needs of companies in industries such as telecommunications, energy, medical and defense. It is possible to plate various metals onto aluminum alloys including nickel, tin, and precious metals such as silver and gold.
A common problem when working with aluminum and aluminum alloys is their tendency to form an oxide that can prevent proper adhesion of the coating. Applying a zinc immersion film as an undercoating before plating the workpiece with nickel can usually alleviate this issue.
A Closer Look at the Various Processes for Plating on Aluminum
Desired results and cost are two primary factors to consider when choosing the best aluminum electroplating process for your manufacturing operation:
- Tin: Tin is a relatively inexpensive metal that can minimize your aluminum alloy plating costs. Tin is often used for plating aluminum electronic components due to its ability to conduct electricity and resist corrosion. Plated tin finishes can range from matte to bright.
- Nickel: While aluminum features a high strength-to-weight ratio, it is softer than many other metals. A nickel-plated coating will increase the hardness of the aluminum alloy substrate and increase corrosion resistance.
- Silver: The energy and power distribution industries rely in silver electroplating of aluminum to improve corrosion protection and surface conductivity. Silver also provides good lubricity and solderability.
- Gold: Although plating gold onto aluminum is a somewhat expensive process, it will not form an oxide on the substrate surface in most cases. Gold's biocompatibility makes it an excellent choice for plating medical devices made from aluminum alloys.
- Electroless nickel: An electroless nickel coating provides exceptional corrosion resistance and will increase the lubricity, hardness and wear resistance of the aluminum substrate. Electroless nickel can also serve as an undercoating to strengthen and promote the adhesion of other plated metals.
SPC Offers Premium Aluminum Electroplating Services
With more than 90 years of metal finishing experience, you can count on SPC to provide superior aluminum electroplating services that will exceed your quality and performance expectations and meet your budget requirements. We also have the expertise to help you select the best aluminum alloy plating process for your manufacturing projects. Contact us for more information today!
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"I would like to thank you for the help you have provided us in developing an electroless nickel plating technique on an unusual substrate. The sample platings you provided show that we should be able to reach our goals. I especially appreciate your willingness to take on an unusual job, with the uncertainties that that entails...We are looking forward to working with you in the future on our plating needs."
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