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Chemical Film Conversion Coating for Sheet Metal


Every week, Team Protocase is bringing you a Proto Tech Tip video, where we’ll give an informative look at a particular aspect of sheet metal fabrication and CNC Machining. This week, Cody from our Engineering & Design Services team covers chemical film conversion coating for sheet metal, and how it’s useful for aluminum parts and enclosures.

Watch the full video below – or, if you’d prefer to read Cody’s Proto Tech Tip, we’ve got the full transcription below.

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Hey everybody, Cody here from Protocase with another Proto Tech Tip. Today we’re going to talk about another one of our in-house finishes: chemical conversion coating for aluminum only.
Chemical conversion coating is often referred to as chem film chromate coating or yellow chromate coating. This is a coating process that applies chromate to the metal. It creates a
surface that is corrosion resistant durable and exhibits stable electrical conductivity.

Our chem film process is done using five different tanks. Parts are hung using a soft stainless steel wire and dipped into these tanks containing solutions for a specified amount of time. The first stage is a 15 to 16 minute dip into a tank containing a cleaning and degreasing solution. The second and third stage is a rinse cycle using reverse osmosis water. The fourth
stage is a 20 to 21 minute dip into a tank containing metal asked EC PN P chem film solution. The fifth and final stage is another rinse cycle. So designers and engineers will opt for chemical conversion coating when they have enclosures or parts that are not painted and they want to protect them from corroding.

Chem film is also really useful for creating reliable electrical connections between aluminum chassis and components. Protocase’s chemical conversion coating process meets a number of specifications and qualifies as type 2 class 1a and 3 under military standard 5 5 4 1f. In simple terms, type 2 means that the process does not utilize toxic or dangerous hexavalent chromium, while class 3 refers to its ability to provide reliable electrical conductivity.

Protocase uses Chemeon TCP-NP which meets the most widely used military specifications for chromate conversion. Applications including military standards 5 5 4 1 F type 2 class 1a and
3 as well as military standard 8 1 7 0 6b. As you can see from the samples in front of me, the coating subtly changes the appearance of the surface, which exhibits nearly clear iridescent with a subtle gold to violet tint. Keep in mind if you are looking to get your parts chem film that we are restricted by the size of our tanks. They are 43.5 inches long, 34 inches wide and 30 inches high.

In conclusion, chem film is an excellent process to add to your enclosure or parts if you’re looking to get great corrosion resistance or to provide a good reliable electrical connection between parts. For more additional information, make sure to check out our chem film page on Protocase.com.

Thanks for watching this week’s video, I hope you found it useful and make sure to check us out next week for another tech tip.

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