Authoritative Answers, Fun, & Aloha -- no cost, no passwords, no popups
(as an eBay Partner & Amazon Affiliate we earn from qualifying purchases)

Home /
Site 🔍
pub     mobile?
Metal finishing Q&As since 1989


A-380 Finishing Options for L.E.D. Emergency Lighting


Hello to all,

My name is Greg Pederson and I am the Director of Engineering for a company that manufactures L.E.D. based emergency warning lights (like the kind found on police vehicles). All of our products are of an Aluminum (6063) extrusion based chassis design, and are always clear or black anodized. We have found this to be a happy marriage and to date; we have suffered no finish failures. We are currently developing a new 360-degree warning light and I am electing to use A-380 die cast alloy (due to the complex geometry). We are exploring the various finishes available and as I have had no experience with finishing A-380 I would be grateful for any assistance. This is an outdoor product operating on such vehicles as snow plows (salt!) trash trucks, and police motorcycles. Main concerns are

1) Corrosion from salt.
2) UV fading over time.
3) Pealing or delaminating.

Has anyone found a cost effective way to anodize this material? (Our part production is projected in the neighborhood of 10-15K units/yr). How well does e-coating or powder coat paint hold up?

Thank you for your considerations in regards to my plight :)

Greg Pederson
- Saint Cloud, Minnesota, USA

UV Additive for Epoxy
on Amazon

(affil links)

Sulfuric acid anodizing can be used successfully on die cast alloys like 380/A380. Chromic acid baths cannot. As always, surface preparation is important. Die lubricants must be removed from the as-cast surface. Subsequent sealing of the anodized layer provides enhanced corrosion protection.

Electrocoating and powder coating are both suitable for enhancing corrosion protection, especially over an anodized layer. Phosphates and other pre-treatments can also be used. Electrocoating almost always involves epoxy based resins, which have poor UV resistance. Powder coating is more common for exterior applications, with the added benefits of color choice, fade resistance, etc. Check out the websites of automotive paint vendors for more information.

Toby Padfield
- Troy, Michigan

The previous answer is best. Powder Coating is the way to go for maximum corrosion protection.

380 is very difficult to anodize because you anodize ALUMINUM. The silicon on the surface does not "anodize", it just turns ugly gray color. Thin walls in 380 casting have more silicon on the surface than thick walls. There are several "dips" recommended in our industry for removing "most" of the silicon from the surface, none are 100% effective. Your anodized 380 castings will never look as good as you are used to seeing on the wrought 6061.

Let us know if you still want more detail information on the surface preparation of 380 die castings.

robert probert
Robert H Probert
Robert H Probert Technical Services
supporting advertiser
Garner, North Carolina

(No "dead threads" here! If this page isn't currently on the Hotline your Q, A, or Comment will restore it)

Q, A, or Comment on THIS thread -or- Start a NEW Thread

Disclaimer: It's not possible to fully diagnose a finishing problem or the hazards of an operation via these pages. All information presented is for general reference and does not represent a professional opinion nor the policy of an author's employer. The internet is largely anonymous & unvetted; some names may be fictitious and some recommendations might be harmful.

If you are seeking a product or service related to metal finishing, please check these Directories:

Chemicals &
& Software

About/Contact  -  Privacy Policy  -  ©1995-2024, Pine Beach, New Jersey, USA  -  about "affil links"