Corrosion Protection SAEJ2334 - HELP

[chadwick1875]

I am investigating corrosion protection on an extruded component. We have steel end fittings that are extruded onto wire. This component is under the vehicle and must meet SAE J2334 test requirements as follows


1 year Appearance Requirement – 15 Cycles SAE J2334 – Immersion Method (1 rating max)

5 year Appearance Requirement – 60 Cycles SAE J2334 – Immersion Method (2 rating max)

10 year Appearance Requirement – 120 Cycles SAE J2334 – Immersion Method (4 rating max)


I currently coat with a phosphate and wax coating, which is easy to extrude on the dies. In the past, when I evaluated any type of zinc coating it gummed up the extruding dies and scraped off during extruding process. Can ant suggest any alternatives that would be easily manufacturable that wouldn’t gum up the dies or scrape off that would still be economical and meet my corrosion requirements? What are the advantages/disadvantages of using a phosphate and wax coating for corrosion protection. I need any information you would have on this as soon as you can. I appreciate any and all help.

Regards,

Chad

Product Engineer

 

[TVP]

First, a phosphate + wax coating is totally insufficient to meet the stated requirements. In order to comply with this the parts will need a very good coating such as zinc phosphate + epoxy electrocoat or a lamellar/multilayer coating such as Magni 565. Second, why can't the parts be extruded and then coated? The answer to your specific question of "What are the advantages/disadvantages of using a phosphate and wax coating for corrosion protection?" are as follows:

Advantages: low cost
Disadvantages: poor corrosion resistance in environments containing chloride ions

 

[chadwick1875]

I can not have a secondary process to coat these parts after they are extruded due to the fact that this in done on the assembly line when the complete assembly is built. What type of plating could withstand the extruding process without scraping off or damaging the dies? The Phosphate plating with wax allows for an easy process. I do use Magni 565 on other components but am afraid this will just scrape off during the extruding process.

My next step I guess would be to evaluate have the steel end fittings plated in some alternative coatings and running them through the extruder and testing to the specifications. Then evaluate the manufacturing process to see if there are any concerns with gumming up the dies.

Any thoughts???

 

[TVP]

I agree that Magni 565 and similar coatings will likely be heavily damaged if they are subjected to deformation. I don't think that there is an easy, drop-in replacement coating that will meet the customer corrosion requirements. I think you would need to change to a stainless steel or aluminum piece in order to keep the manufacturing process the same. You may be able to implement a spray process after the extrusion operation where either a paint-type coating (epoxy, polyester powder, etc.) or a metal-filled organic (Magni, etc.) can be selectively applied to the desired area. Obviously not the solution you want, but automotive underhood/chassis environments require very good coatings in order to resist corrosion.

 

[CoryPad]

I agree, there doesn't seem to be a "standard" coating that would work for this application. I cannot think of any automotive parts that are manufactured in the way you describe, and if there were, they would have to be coated after extrusion.

You might be able to use a thick metallic layer (aluminium, nickel, copper) that will flow during extrusion, but that likely will abrade and cause contamination like the thin zinc layer did.

Is your extrusion process crucial? There are many ways to attach parts (staking, fasteners, welding, press fit, etc.). I don't see any way to meet the customer's requirements and keep your current process.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[rheo565]

i would definitely recommend trying the magni 565 coating. this coating seems to handle environmental testing very well.