If your manufacturing company creates products consisting of metals, you know how important metal finishing is. Metal finishing processes are used to protect, improve performance, and/or enhance the appearance of an enormous variety of products. There are many different types of metal finishing options, however. How do you know which option is best for your product?
What Is Metal Finishing?
Metal finishing can be a physical, chemical, or mechanical process. It involves applying a metal coating or other treatment to the surface of a part. We refer to that part as a substrate. The substrate does not have to be metal, so the term “metal finishing” is somewhat misleading. Many parts that when finished look like they are composed completely of metal are actually plastic with a thin layer of metal finishing.
Industries that often use metal finishing to make their products stronger, more damage resistant, and attractive include:
- Aerospace
- Automotive
- Electronics
- Medical
- Kitchen and Bath
- Musical Instruments
- Consumer Products
Additional benefits of metal finishing are: increased surface thickness, strength, and product durability. It can also provide greater resistance to corrosion or chemicals, greater wear resistance, increased electrical resistance and conductivity, surface hardness, torque tolerance, and adhesion.
Which Metal Finishing Option Is Best?
Metal finishing is the overall term that we use to describe the final phase of part manufacturing, but it’s not one process. Many different processes can be used to finish parts. The challenge is to find the best metal finishing option for your parts, the one that will make them most suited to their intended use. Here’s a short overview of the possibilities:
Plating
The most common type of industrial plating is electroplating, and it can be done on either plastic or metal parts.
Plating on Plastics — ABS (Acrylonitrile Butadiene Styrene) plastics have the highest volume usage for commercial plating applications. The chemistry of the resin lends itself favorably to the processing techniques used to obtain smooth, adherent metal deposits.
To plate on ABS and ABS/PC plastics, the substrate first undergoes a pre-plate process that essentially serves to metallize the plastic. First, the substrate is etched, creating bonding site for the metallic layer. The remaining etchant material is then neutralized, a film of palladium and tin is applied, and the tin is oxidized. Electroless nickel is then deposited on the part to metallize it and allow an electrical current to be introduced and maintained during electroplating. During the electroplating process, the component is plated first with acid copper, then various nickel composites, and finally chromium.
Metal Plating — When performing decorative plating on a metal substrate, the component first undergoes a process to condition and clean the surface. The component is then subjected to plating baths where the desired metals are deposited on the component. For functional finishes, a component is cleaned, then subjected to passivation baths, which maximize the component’s resistance to corrosion.
Gold Plating — ECF performs both decorative (hard) and reflective (pure) 24K gold plating for a variety of applications. We also offer high-performance, gold-look PVD finishes through our environmentally-friendly PVD process.
Electroless Nickel Plating — A popular plating option because of its uniformity, lubricity, solderability and highly corrosion resistance, electroless nickel plating is a process that uses a chemical reaction to co-deposit a nickel-phosphorus coating onto a desired substrate. Parts can be post hardened through baking to produce higher wear resistance than those that aren’t baked.
Electroless nickel plating differs from other electroplating processes because it does not require electricity.
ECF also has the capability to perform decorative plating on plastic, and both decorative and functional plating on metal substrates. We perform gold, chrome, tin, nickel, and electroless nickel plating on metal substrates, which include steel, stainless steel, brass, aluminum, and more.
Physical vapor deposition (PVD)
PVD represents a family of modern coating fabrication processes, all of which are performed in an artificially created vacuum, usually in a vacuum chamber. PVD coatings specifically designed for decorative applications in consumer-oriented industries such as plumbing and building hardware, automotive, and electronics are mostly ceramic coatings. Ceramic PVD coatings offer a unique combination of vivid aesthetic appeal, through a wide array of color finishes, and superb mechanical and chemical properties, which few metals and organic films can match.
ECF has in-house capability to produce ceramic and metallic alloy decorative PVD coatings through magnetron sputter and cathode arc evaporation processes. This allows us to customize coating color, specific gravity, microstructure, and compositional and structural gradient, continuous or multi-layered, to your specifications.
Trivalent Chrome
Trivalent chromium plating is an environmentally responsible technology with the performance and aesthetic benefits of traditional plating methods. ECF has the capability to produce a variety of bright and dark trivalent chrome finishes using both sulfate and chloride electrolyte systems, many of which are automotive OEM qualified finishes.
In Russia they use calcium chloride on roads to melt the salt, clay/mud roads hold the salt year-round. Trivalent chrome is a better choice for automobiles or vehicles exposed to calcium chloride salts because it has more corrosion resistant than hexavalent chrome
Paint over Chrome
Many new colors and finishes can be achieved by the paint over chrome process. It is common to see black translucent and opaque finishes in the kitchen and bath and automotive markets.
ECF has the capability to apply a number of performance based paints or coatings over hexavalent and trivalent chromes. These paints and coatings can be clear, translucent, or opaque as determined by our customer.
Making Your Metal Finishing Choice
Before you decide which metal finishing process would be best, it’s important to take certain factors into consideration. The first question to answer is: How do you want your part to be improved? If your focus is sharpening or improving the appearance of the product you will likely choose a different option than if your goal is a functional improvement.
Cost will be a factor too, of course. Some processes are more costly to do. On the other hand, they may offer better benefits to your parts.
If you need help determining which metal finishing process is best for your product, Electro Chemical Finishing would be glad to offer our assistance. We are capable, experienced, and knowledgeable about all of the above finishing processes. We will work with you to create customized metal finishing for your parts that will reduce your costs, meet your production goals, provide excellent products to your customers. If you’re looking for a reliable and affordable surface finishing company, look no further than ECF.