Do I need to show fasteners in my BOM's/DMR etc?

[ccwerner55]

Hi
We are working toward submittal of a Class II medical device on a 510(k). I would like to know if I need to show and report the fasteners on my assembly dwgs, BOM's, DMR's, etc.

The same question applies to discretes on assembled PCB's. Am I required to report them or can I simply list the top-level assembled PCB on my sub-assembly BOM? I buy the assembled board complete as a top level p/n.

I think I know the answer but wanted to post this and obtain feedback.

Thanks
Chris

 

[Ronen E]

Hi
We are working toward submittal of a Class II medical device on a 510(k). I would like to know if I need to show and report the fasteners on my assembly dwgs, BOM's, DMR's, etc.

The same question applies to discretes on assembled PCB's. Am I required to report them or can I simply list the top-level assembled PCB on my sub-assembly BOM? I buy the assembled board complete as a top level p/n.

I think I know the answer but wanted to post this and obtain feedback.

Thanks
Chris

Hello and welcome to the Cove

The answer to the first question depends on what the device is and what's the fasteners' role in it. As a generic answer I would say "include everything" (for a host of reasons), but I guess some slack may be allowed depending on specifics.

2nd question - As long as that PCB is 100% BOMed somewhere (e.g. by its manufacturer), and you know you'll be able to access all details that bear on device safety and effectiveness, at will, in a timely manner and with confidence -- you may omit those details from your BOM. If you intend to rely on that route, better have it formally documented and signed off by your supplier. Further, if you intend to treat that PCB as a "black box" (in terms of materials etc.), your risk analysis should take into account possible worst-case consequences.

Cheers,
Ronen.

 

[ccwerner55]

Hello and welcome to the Cove

The answer to the first question depends on what the device is and what's the fasteners' role in it. As a generic answer I would say "include everything" (for a host of reasons), but I guess some slack may be allowed depending on specifics.

2nd question - As long as that PCB is 100% BOMed somewhere (e.g. by its manufacturer), and you know you'll be able to access all details that bear on device safety and effectiveness, at will, in a timely manner and with confidence -- you may omit those details from your BOM. If you intend to rely on that route, better have it formally documented and signed off by your supplier. Further, if you intend to treat that PCB as a "black box" (in terms of materials etc.), your risk analysis should take into account possible worst-case consequences.

Cheers,
Ronen.

Hi Ronen
Thanks for your reply. I have always tried to include all details including fasteners in my BOM's. The current thinking might have changed and I wanted to gain another opinion.
As to PCB's, since we do not do any value added activity and buy them complete, I think black boxing is OK, assuming I can get the schematic, netlist, artwork, etc from the manufacturer. I'll need to verify that before making a final decision.
Best
Chris

 

[Wes Bucey]

When my company made components for medical devices, the customers were extremely specific in the list of features and materials. Since we sometimes made components that would go two or three links up the supply chain before reaching the OEM, we saw that the requirements came down in such specificity from the top dog. If we made a fastener that was identical to one that could be bought off the shelf EXCEPT for material analysis, we certainly expected the material to be an intrinsic part of the design, not just a whim.

To illustrate in a small, prosaic way the consequences of NOT being specific, here's my "tea kettle" saga.

I bought a stainless steel tea kettle a few years back which had a really slick design that I admired and wanted for my kitchen. After two weeks of use, I noticed the bolt which held the heat proof knob on the lid was rusting away, dropping oxide flakes into the kettle. Being a geek with metallurgist friends and curious, I schlepped the lid to a friend's lab to discover, through spectroanalysis, that the bolt was plain carbon steel. Apparently, to save a fraction of a cent per kettle, one of the suppliers had used carbon steel for the bolt versus stainless. Was it fraud? ignorance? stupidity? a misunderstanding? Who cares? I not only wrote the manufacturer (brand name withheld) off my "supplier list," but I wrote the retail store chain off, too. The $20 or $30 I paid for the kettle didn't justify my time and effort to give unpaid consulting advice to either. Whatever happened to FMEA?​

 

[ccwerner55]

Thanks Wes
Great feedback. I feel your pain on the carbon steel fastener story.

 

[Wes Bucey]

Thanks Wes
Great feedback. I feel your pain on the carbon steel fastener story.

Yep. The main "moral" to that story is that neither the manufacturer nor the retail chain know WHY I stopped buying from them, but they also don't know how many others to whom I have told the story over the years may have been influenced by my story to also stop buying. [side note - both manufacturer and retail chain no longer exist! I don't think my kettle was the sole cause, just a symptom.]

If I were the medical device manufacturer who did NOT specify materials and other details on my product which subsequently caused problems for users down the line, how would I know how many were bad mouthing me and my product instead of raising the issue with me directly?

As a long time acquaintance, Dale Dauten, the Corporate Curmudgeon, describes it, WOMP (Word of Mouth Potential) can work for you or against you. Worse, people are usually quicker to tell others of a bad experience than a good one.

 

[Ronen E]

When my company made components for medical devices, the customers were extremely specific in the list of features and materials. Since we sometimes made components that would go two or three links up the supply chain before reaching the OEM, we saw that the requirements came down in such specificity from the top dog. If we made a fastener that was identical to one that could be bought off the shelf EXCEPT for material analysis, we certainly expected the material to be an intrinsic part of the design, not just a whim.

To illustrate in a small, prosaic way the consequences of NOT being specific, here's my "tea kettle" saga.

I bought a stainless steel tea kettle a few years back which had a really slick design that I admired and wanted for my kitchen. After two weeks of use, I noticed the bolt which held the heat proof knob on the lid was rusting away, dropping oxide flakes into the kettle. Being a geek with metallurgist friends and curious, I schlepped the lid to a friend's lab to discover, through spectroanalysis, that the bolt was plain carbon steel. Apparently, to save a fraction of a cent per kettle, one of the suppliers had used carbon steel for the bolt versus stainless. Was it fraud? ignorance? stupidity? a misunderstanding? Who cares? I not only wrote the manufacturer (brand name withheld) off my "supplier list," but I wrote the retail store chain off, too. The $20 or $30 I paid for the kettle didn't justify my time and effort to give unpaid consulting advice to either. Whatever happened to FMEA?
​

I'm not saying this was the case, but "Stainless Steel" is not an absolute term and even Stainless Steel corodes sometimes, not necessarily in harsh conditions.

Cheers,
Ronen.

 

[Wes Bucey]

I'm not saying this was the case, but "Stainless Steel" is not an absolute term and even Stainless Steel corodes sometimes, not necessarily in harsh conditions.

Cheers,
Ronen.

Spectroanalysis showed no detectable chromium - primary requirement to make steel "stainless"

I would have expected either 304 or 316 stainless grades - the body of the kettle was 304 stainless.

In my life in the contract machining business, we dealt with many different alloys and nonferrous metals. This was definitely a plain carbon steel bolt, thread rolled and not heat treated to any appreciable hardness.