Manufacturers turn to metal finishing solutions to provide corrosion resistance, surface hardness, or other mechanical property improvements to their metal components.
Metal finishing may involve different coating techniques including electroplating, where the coating and the metal components are immersed in an electrolytic “bath.” An electric current is then applied to oxidize the metal atoms, depositing the coating onto the component and changing its surface properties.
Because many of ESI’s metal stamping customers ask questions about the best finishing options for their projects, we’ve teamed up with one of our finishing partners – Northeast Metal Works – to put together a short step-by-step guide on selecting the appropriate metal finishing for your project.
Step 1: Identify Corrosion Resistance Needs
Different finishes offer varying degrees of corrosion resistance. It’s essential that materials are matched to both the environment they’ll be operating in, as well as to the length of time they can resist corrosion.
ESI examined some of the most popular metal finishes, the applications using those finishes, and the hours each finish could withstand damage caused by oxidation or other chemical reactions. These finishes were then categorized by their salt spray test results — a standardized corrosion test method where salt spray is applied to coatings and appearance is evaluated over time. The longer the period of time before corrosion or rust appears, the higher the material’s corrosion resistance.
High corrosion resistance indicates that a finishing material can protect a component from salt spray for over 1,000 hours, while some finishes may only provide protection from water alone for up to 50 hours. For example, here are two finishes that feature significantly different results:
- Imitation chrome tends to be costly because of its aesthetic and corrosion-resistant properties. Offering a bright silver finish, excellent lubricity and corrosion resistance, imitation chrome is also environmentally friendly and is sought by manufacturers in the marine and medical industries.
- Zinc is not as resistant to corrosion as imitation chrome, making it lower in cost. That being said, it offers other notable properties like ductility and adhesion, making it an ideal finish for automotive and industrial manufacturers.
Step 2: Analyze Pricing
Pricing is a significant factor in the finishing selection process. The level of corrosion resistance and aesthetic qualities will impact price, but keep in mind that other factors can influence pricing, as well, including:
- Market conditions
- Finish availability
- Complexity of coating process
For example, barrel paint is widely considered to be an inexpensive finish. It is frequently utilized by the consumer product and construction industries due to its ready availability in many colors.
Barrel paint can be cheaper than powder coating options and offers full coverage. However, it is not nearly as durable as a powder coat. It can also only be applied to parts with simple shapes. This influences how pricing actually plays out over the lifetime of an item and what that means for your company’s budget.
Step 3: Consider Other Needs: Aesthetics, Thermal Conductivity, and More
Products that will be visible in their end use typically require aesthetic considerations. When selecting finishes by aesthetic appearance, factors include:
- Color availability
- Matte vs. gloss choices
Based on the application, electrical or thermal conductivity may come into play as well. The medical industry in particular often requires components that offer electrical or thermal conductivity. Furthermore it is essential that coatings for medical devices – such as pacemakers or artificial hips – do not pose any harm to human tissue. As such, the cytotoxicity potential and medical cleanliness of surfaces must be taken into account, and should play a part in the selection process for finishing materials.
If you aren’t sure which finishing option is best for you, work with an expert. ESI offers complete services from design to delivery so you can receive a finished metal component without having to worry about moving it between providers. For more information, download our Metal Finishing Selection Guide today.