AERHEAD2

Re: MIL-DTL-5541-F use or not use type I

MIL-DTL-5541-F

I am a new bee.

I need to know when to use type I and not to use type I finish.

Is there a 'white paper' or guide out there that when and why type I really needs to be used.

I have a person at work that thinks that type II is colorless and is using type I with out really being needed to provide color

I think he is confused with class 1A.

aerhead2  sad

Southern Metal Finishing

Re: MIL-DTL-5541-F use or not use type I

"3"

Southern Metal Finishing's Website

AERHEAD2

Re: MIL-DTL-5541-F use or not use type I

I posted the MIL-DTL-5541-F use or not use type I Chemical Conversion Coating and the person I work with says the answer from southern is incorrect that it has to do with Anodizing and not Chemical Coversion Coating.

HELP!!!!

Ira Donovan

Re: MIL-DTL-5541-F use or not use type I

Dear AERHEAD2,

The major differences between the Class 1A and 3 have to do with the electrical resitace properties of the coating.  The Class 3 may appear slightly lighter in color due to the difference in film thickness.  Both coatings shall meet the overall corrosion resistance qualities, however the class 3 will have a lower electrical resistance, thus is frequently used in mating applications for conductivity.

Ira Donovan's Website

Labrat

Re: MIL-DTL-5541-F use or not use type I

MIL-DTL-5541F is a detailed spec for a chemical conversion coating over aluminum. In a Type I coating, the chemical composition contains hexavalent chrome. Type II contains no hexavalent chrome. Class 1A is for maximum corrosion protection, Class 3 is for corrosion protection where low electrical resistance is required. Class 3 will result in a thinner deposit, thus less resistant to corrosion than Class 1A.
In response to your question of when each type and class should be used, I would assume that since the customer is using a detail spec, they would also specify the class and type. If the class is not specified, I would go with Class 1A.
Southern Metal Finishing was correct about the different types, just for a different spec. I am sure he was referring to an anodizing spec, such as MIL-A-8625. Sometimes the types and classes for aluminum finishing can be a bit confusing.