Why Zinc Plating?

Most people you talk to about zinc electroplating, have very little knowledge of what  that process means, or why you would want to perform it. As you go a little deeper into the explanation of what zinc electroplating entails, they begin to see the picture.
Looking at a car, there are many parts that will corrode from exposure to water and salt from the roads. The corrosion leads to part failure if left unchecked. The next question that comes to mind is, how do you protect these parts? Answer: You add a coating on top of the parts to slow down or prevent corrosion. There are a variety of coatings available to perform this task with just as large a variety in costs. Some examples of coatings are powder coating, E-coating, wet paint, galvanizing, zinc flake, zinc plating, nickel-chrome plating, hard chrome and electroless nickel plating covers most of the coatings used today. Ranking them lowest to highest in cost per mil/ft2, they would be:
  • Galvanizing
  • Zinc plate
  • Wet paint
  • Zinc flake
  • Powder coating
  • E-coating
  • Hard chrome
  • Nickel-chrome
  • Electroless nickel
In recent years the zinc plate, zinc flake, powder coating and E-coating have become very similar in cost and are used on similar parts. Galvanizing parts will give you many years of serviceable life, however it can only be done on low strength steel parts and has a dull rough finish. Typical galvanized parts can go 30 years before rusting.
Consumers today look at a product and want something that is either very shiny or something that blends together in all the same color. While the chrome, nickel-chrome and electroless nickel plated parts provide a shiny finish, they also cost the most as much as 80% more than zinc plate. So depending on the service life you want out of the coated part, you are left with inorganic zinc plate, and s few organic coatings (zinc flake, E-coating, powder coating, and wet paint). Of course, cost is also an issue. Zinc plate is the lowest cost for most applications.
Next, you must look at part geometry. Can the entire part be coated effectively? Does the part have deep recesses? Do you need a shiny finish or blend-in type finish? Will the part get impacted in use? Parts with complex geometry, that will be impacted and have deep recesses, tend to not coat well with organic coatings. Organic coatings currently only can be used for blend-in type finishes; no shiny finish is available. Many advances recently in zinc plate have allowed for shiny and blend in finishes that is impact resistant.
So if you are looking to coat a complex part with a shiny finish or a blend in finish that will get impacted, the answer is zinc plate!