26.11.2015 um 7:54 AM #15069
I am unable to see a difference between a process element and a system element.
I try to build a process FMEA. I have only used process elements so far for all three levels.
When should I use a process element and when a system element?26.11.2015 um 11:58 AM #17172
System elements and process elements have different icons. In addition the name is different which will be shown in some views as a label.
Conversion from system element to process element is possible via the context menue (= right mouse).
Process engineers have pointed out that a three level structure for PFMEA looks like this:
System element – Process element – System element
(effect level) – (failure level) – (cause level)
The element on the second level, the failure level can be seen as a process step in a production line which will become a member of processs flow diagrams (PFD), FMEA and control plans (CP).26.11.2015 um 4:34 PM #17173
Thank you Jürgen.
I have tried different approaches and am still a bit unsure what the best structure for a Process FMEA is. It is great to hear from an authority.
Recently I have tried something weird like this:
Production line > Station > System element
And so that the individual process steps are actually functions inside the station.
Everything looks good so far and the FMEA also looks good. Converting some of the process steps to product characteristics will add them to the Control Plan. Then I have to rename the process step a little for it to make sense in the Control plan.
„Add bolt to hole“ in FMEA becomes „Bolt length“ for example.
PS! I think there is no correct place in the forums to ask „how to“ questions.27.11.2015 um 9:59 AM #17174
Using functions as process is not a good idea.
„Add bolt to hole“ is rather a function of a process step „Assembly“ / „Assembly bolt“.
Sorry if you now have to spend some time to input additonal objects but it may not be so problematic because moving object via Drag&Drop is pretty simple.
From the viewpoint of FMEA it is possible to convert functions to product characteristic so that it is visible in the CP.
Although it can make sense for easier differntiation to use both, functions and product characteristics. E.g. if you want to discuss dirt on bolt surface due to dirty hands of the operator then this can hardly be seen as something in correlation with bolt length.
You are welcome to discuss with us and the other experts from our user group whatever will solve your questions.27.11.2015 um 2:32 PM #17175
What would than be a good idea how to include stations in the structure? Like this?
Line > Station > Process step > System element for causes
Because I had the following
Line > „ST10 Bolt assembly“ > System element for causes
And the structure in the station:
(Function) Take bolt and place into hole
(Product characteristic) Bolt type
(Product characteristic) Bolt length
(Function) Do something else now
(Product character) Length of something
So kind of a mix between the tasks you have to do in this station as (Function) and also a specific characteristic.
I kind of understand that you say that I will run into trouble later if I use this method but I don’t see it being any different than having all the tasks as process elements. Can you clarify?30.11.2015 um 8:25 AM #17176
You have written “And so that the individual process steps are actually functions inside the station.” I have interpreted these functions as IQ objects functions (= process step).
BTW Some users of Excel forms for PFMEA do not know what to input into the function column and/or the column is titled “Process/Function”.
Your example shows it more clearly and I do not see anything which has to be changed. My suggestion is to stay with the approach you have chosen.
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