Failure Mode help for Assembly Processes

I

iandb

#1
Hi All,

I work for a re-manufacturing company in the uk & we are in the process of putting value in to FMEA's that have been poorly written. Having under gone external training our group are struggling to identify the failure modes that you can have during assembly. We are hoping that you kind people can guide us, maybe provide an example FMEA covering an assembly process? The basic flow is ...... receive core (transmissions / engines), strip, wash, reclamation, rinse, inspection, kitting, assembly, test, pack & despatch.
We are okay with modes for wash i.e dirty, damaged.
We would really appreciate some help on this.
Thank you all in advance for your assistance.
 
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Jim Wynne

Staff member
Admin
#2
Hi All,

I work for a re-manufacturing company in the uk & we are in the process of putting value in to FMEA's that have been poorly written. Having under gone external training our group are struggling to identify the failure modes that you can have during assembly. We are hoping that you kind people can guide us, maybe provide an example FMEA covering an assembly process? The basic flow is ...... receive core (transmissions / engines), strip, wash, reclamation, rinse, inspection, kitting, assembly, test, pack & despatch.
We are okay with modes for wash i.e dirty, damaged.
We would really appreciate some help on this.
Thank you all in advance for your assistance.
Think in terms of process failures, not product defects. If you understand the process, then you also understand how it might fail.
 
H

Howard Lee

#3
Just like Jim says, make a list of ALL of the things that could go wrong in your process. When you have finished the list, know in your heart that there is something that you have overlooked.

Here's a personal tip: There will be something in your list with which everyone will agree, "No one would ever be stupid enough to do that!"
Put this at the top of the list.
 
I

iandb

#4
Thank you Howard & Jim.The difficulty we have is most of the products have been designed to only be fitted in one orientation (thank goodness for design engineers!) so the only thing we generally can do is miss putting in the component & even that either stops us from continuing to build or we pick it up on test. Can you have failure modes as "cannot fit bearing" or cannot fit clutch case etc?
Our plan is to make a comprehensive failure mode list but things do not flow in our thought patterns!
 

Stijloor

Staff member
Super Moderator
#5
Can you have failure modes as "cannot fit bearing" or cannot fit clutch case etc? Our plan is to make a comprehensive failure mode list but things do not flow in our thought patterns!
Hello iandb,

In an assembly process, "cannot fit bearing" or "cannot fit clutch case" are indeed failure modes. If the process step is: "Fit (or install) bearing", one of the failure modes associated with this process step is: "cannot fit bearing."

I assume that your focus is the assembly process? Because a failure mode observed in the assembly process can be the effect of a machining process failure. Here is where people get confused.

Here is a good technique to avoid confusion:
  1. What can possibly go wrong? The answer is the failure mode.
  2. If this failure mode occurs, who or what will be affected? The answer is the effect or effects.
  3. What is causing the failure mode to occur? The answer are the causes.
Keep focused on the process step under review. (Let historical product and process information be your guide.)

I'll look for additional information.

Stijloor.
 
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I

iandb

#6
Hi Stijloor

Thank you very much for your comments. They are very helpful. It is indeed confusing to us all when we are deciding the failure mode & the causes. We do get them the wrong way round but are gradually understanding the differences.The effects of our assembly are quite generic such as "test failure, rework, production delay etc.
Any further comments will greatly be appreciated.
 

Stijloor

Staff member
Super Moderator
#7
Hi Stijloor

Thank you very much for your comments. They are very helpful. It is indeed confusing to us all when we are deciding the failure mode & the causes. We do get them the wrong way round but are gradually understanding the differences.The effects of our assembly are quite generic such as "test failure, rework, production delay etc.
Any further comments will greatly be appreciated.
Hello iandb,

You are very welcome! Attached is a tool that may help. Post it on the wall or on a flipchart to remind Core Team members and keep their creative FMEA thoughts straight.

Stijloor.
 

Attachments

Jim Wynne

Staff member
Admin
#8
I assume that your focus is the assembly process? Because a failure mode observed in the assembly process can be the effect of a machining process failure.
With the exception of inspection processes, it should be assumed that material is entering the current operation in conforming condition. The focus shouldn't be on what might have gone wrong upstream (that's another PFMEA), but what might go wrong in this process.
 
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