DFMEA, Drawings and PFMEA of an Assembly Process

[nitros1]

Hi all !!


Im currently assigned to complete a PFMEA of an assembly process, for starters I know to look for info, in the DFMEA, component drawings, similar processes, other PFMEAS, and probably some others that I am omiting.

Anyways when I look in the component drawings I find some dimensions denoted as HI, and SC, but I find none of them mentioned in the DFMEA, ( the DFMEA has no classifications whatsoever), when I asked the product engineer responsible, he replied that the order was, DFMEA-drawing- PFMEA, but isn{t the drawing a depository of all DFMEA findings ?? how can I link these 2 documents so I can transfer all that I should to my PFMEA??


Thanks in advance.

 

[GStough]

Hi all !!


Im currently assigned to complete a PFMEA of an assembly process, for starters I know to look for info, in the DFMEA, component drawings, similar processes, other PFMEAS, and probably some others that I am omiting.

Anyways when I look in the component drawings I find some dimensions denoted as HI, and SC, but I find none of them mentioned in the DFMEA, ( the DFMEA has no classifications whatsoever), when I asked the product engineer responsible, he replied that the order was, DFMEA-drawing- PFMEA, but isn{t the drawing a depository of all DFMEA findings ?? how can I link these 2 documents so I can transfer all that I should to my PFMEA??


Thanks in advance.

BUMP......

Can anyone help?

Thanks!

 

[Antyp]

Hi

DFMEA in fact is used to asses design of the product and to define special characteristics (risks within the design of product).
Link between DFMEA and the Drawing should be obvious by product characteristics / functions. However when you work over DFMEA there is no final drawing yet.

PFMEA is a process analysis, its starting point is Flow Chart, not the drawing nor even DFMEA.
In PFMEA you analyse all requirements for the process not product.
Connection can be found by so called characteristics matrix, which shows in which process step (operation) particular product characteristics are created / used controlled etc.

 

[nitros1]

Hi

DFMEA in fact is used to asses design of the product and to define special characteristics (risks within the design of product).
Link between DFMEA and the Drawing should be obvious by product characteristics / functions. However when you work over DFMEA there is no final drawing yet.

PFMEA is a process analysis, its starting point is Flow Chart, not the drawing nor even DFMEA.
In PFMEA you analyse all requirements for the process not product.
Connection can be found by so called characteristics matrix, which shows in which process step (operation) particular product characteristics are created / used controlled etc.

Ok thanks for taking the time to help me, well that{s pretty much what I ve heard , but in this case I lack the characteristics matrix, and I dont want to miss any important or critical characteristic mentioned in the DFMEA nor I want to include it all, all I have is a DFMEA with severities no biggger than 8, no classifications for any failure mode at all, and a drawing with a bunch of SCs and HIs, and I have to complete the PFMEA. Advice?

 

[yodon]

As Antyp noted, the pFMEA is intended to focus on the process. Set the dFMEA aside and look at the manufacturing process. There are likely individual steps in the process. The pFMEA looks at what can go wrong at each step. Your controls are then activities that reduce the likelihood of such failures (maybe in-process test, maybe QC inspection, etc.).

Do you have a System Hazard Analysis? If so, that should be the place to look to determine the types of hazards that can arise through use and you should be able to relate process failures to those.

 

[nitros1]

No I dont have that, or either I know it by another name, could you explain please?

 

[yodon]

Sure. I tend to think in terms of medical devices so I probably jumped too far.

The system hazard analysis just defines the hazards associated with the product and the possible harms. We use that information to frame up the pFMEA. If the result of a process could result in a defect that could result in harm then that gets more attention than a defect that wouldn't cause harm.

But if you don't have one, you can still drive the pFMEA. One way would be to flowchart the assembly process. Look at each step in the process and ask what could go wrong and what kind of impact that would have. Where conditions exist that would have adverse impact to the product, define actions (mitigations or controls) to eliminate or reduce the likelihood of the defect escaping.

 

[noorain]

I have been assigned to initiate, DFMEA in our company. We are designing and developing a medical product. There has been an initial BOM. My production manager feels FMEA should start only after PCB design is completed. IM a bit lost as im new to this process, I dono when it should be started. Any help would be very much appreciated.

 

[noorain]

I need help in starting DFMEA. Should i initiate it once the design is completed or while its being done. Please do suggest. from when to start

 

[yodon]

An FMEA (as Risk Management in general) is not a static, one-time document. Start now with what you know and updated it throughout the process. By starting now, you may be able to better evolve the design towards a safer product.

If you haven't done so already, you should do the System Hazard Analysis work to fully characterize the device and to get a baseline understanding of the associated hazards. That will help set the foundation for the dFMEA.