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What is the difference between MIL-C-5541E and MIL-DTL-5541F? What about QPL-81706 / MIL-DTL-81706?

March 18, 2008

Q. I need to determine the difference between a reference to Mil-C-5541 [link is to spec at TechStreet] E and Mil-DTL-5541 [link is to free spec at Defense Logistics Agency, dla.mil]F as the certification that I receive with material contains a reference to MIL-C-5541E. That certification recently changed to MIL-DTL-5541F. Can anyone shed light on this?

Debbie Kidder
regulatory affairs - Minnetonka, Minnesota, USA


March 28, 2008

A. The actual change, I believe, is that TCP (trivalent chromate product) is now permitted under Mil-DTL-5541 [link is to spec at TechStreet]F.

Why the "style" of the spec went from "C" to "DTL", I don't know and I hope that someone can help us out. My understanding is that DTL is an abbreviation for 'detail' and is used when a spec requires that certain details, as opposed to a performance spec, but I'm not in the loop.

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


April 8, 2008

A. Hey, at least they upped the revision letter!

I agree, Ted -- the biggest difference between MIL-C-5541E and MIL-DTL-5541F is that the buyer can ask for a "Type II" coating which will contain no hexavalent chromium. Currently, only the trivalent chromate formulation developed by NAVAIR is listed in the Mil-DTL-81706 [link is to spec at TechStreet] spec, which governs the materials one can use for a proper MIL-DTL-5541 coating.

We consider a cert with "MIL-DTL-5541F" to be acceptable for parts requiring chemical conversion coating per MIL-C-5541.

The "DTL" is indeed short for "detail", and was done to reflect the move away from 'how-to' type specifications, to one that merely lists the important details of the requirements. I have to say I'm not certain of the difference between a 'detail' specification and a 'performance' specification such as MIL-PRF-46010 [link is to spec at TechStreet], which lists the performance criteria the coating is supposed to withstand.

By the way, the letter in the Mil and Fed specs is merely the first letter in the title of the specification. So here "C" is for "Chemical", and in QQ-P-35 [link is to free spec at Defense Logistics Agency, dla.mil], the "P" was for "Passivation".

It doesn't have to make sense.

Lee Gearhart
metallurgist
East Aurora, New York


April 28, 2011appended

Q. We use AL 6061-T6 parts finished with Chromate Conversion Coating per MIL-C-5441 Class 3.
Is this coating RoHS compliant? I was not able to find MIL-C-5441 spec on the net, is it still active?

Alex Sidorovsky
Component Engineer - San Jose, California

January 10, 2012

A. Mr. Sidorovsky, I hope you've got the answer to your question by now but my two cents after poring over the specs for a couple hours:

If the drawing doesn't specify Type II (non-hexavalent chromium), then it shouldn't be RoHS compliant. 5541 says to default to hex chrome material (Type I) if a material type isn't specified in the contract. For a copy of 5541 (it's now MIL-DTL-5541) and other mil specs, go to  assist.daps.dla.mil/quicksearch/  or www.landandmaritime.dla.mil/Programs/MilSpec/DocSearch.aspx

Jason Mansfield
- Milwaukee, Wisconsin, USA

----
Ed. note, April 2014: the URL for the 'assist' site is presently quicksearch.dla.mil/



January 10, 2012

Q. This looks like a good place to post the related question:

What are the differences between MIL-DTL-5541 and '81706?

The only thing I can discern is the performance of the coating; 5541 test samples are allowed corrosion after testing and 81706 samples aren't? All the chemicals used are identical.

Thanks for your comments!

Jason Mansfield
- Milwaukee, Wisconsin, USA


January 12, 2012

A. Through conversations with others, I was able to grasp the difference between MIL-DTL-81706 and MIL-DTL-5541 and wanted to post for anyone else who may have questions about it:

81706 is the spec to which the conversion coatings themselves are qualified. Suppliers develop materials and processes that are approved for use after much testing. This is the "theoretical standard" to be met under ideal conditions.

5541 is the spec against which the manufacturer measures their coating _process_ to ensure that the process is being performed properly. Allowance is made for manufacturing tolerances and consumption of the chemical after processing several lots, hence an allowance for slight corrosion. This is the "practical standard" to be met under real life conditions of manufacturing.

Jason Mansfield
- Milwaukee, Wisconsin, USA



Chromating Specifications

April 30, 2014appended

Q. What is the difference between MIL-C-5541F and MIL-DTL-81706B. My customer is asking for parts to certified to both specifications, I have never run into MIL-C-81706B.

R Webb
Quality Assurance - Bloomingdale, Illinois USA
  ^- Privately contact this inquirer -^


April 2014

A. Hi R. We appended your question to a thread which hopefully answers it for you. Supplier companies like Henkel, MacDermid, Chemetall, etc., get their products qualified to be listed in MIL-DTL-81706 (used to be QPL-81706 for 'Qualified Products List'), then you as the applicator follow the instructions in MIL-DTL-5541, but you must use one of the products listed in MIL-DTL-81706 when doing so.

Regards,

pic of Ted Mooney Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey

May 1, 2014

thumbsup2Thanks for your help and linking my question to a previous thread. Nothing like a conversation that spans a few years!

R. Webb [returning]
- Bloomingdale, Illinois USA

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