How to align sequence of events in an Hybrid template of PFMEA and ISO 14971?

Quality Engineer

Starting to get Involved
In our PFMEA template we have Process step, funciton, failure mode and failure mode cause column. I am confused on how to clearly and correctly input every field.

Example 1:
Process step: Adjust the water flow meter to 0.3-0.4 gal/min and monitor the water flow, argon pressure and laser performance (using camera) throughout the cutting process
Function: To set and maintain the appropriate water flow rate and argon pressure while continuously monitoring laser performance to ensure consistent and high-quality cutting results
Failure mode: Water flow out of spec - thermal damage/shock, burn marks (compromised structural integrity)
Failure mode cause:
1. Incorrect adjustment.
2. Defective flow meter.
3. Incorrect set-up of equipment.

Example 2:
Process step: Once the laser is at the welding location, select the weld start and stop point using A and B commands on laser unit
Function: To achieve correct weld alignment
Failure mode: Incorrect weld start and/or stop points - misaligned weld (weld strength compromised)
Failure mode cause: Operator didn't follow the process instructions

According to some team members, water flow out of spec and incorrect weld start and/or stop points is a cause of failure.
What is the opinion of you people here that how the failure mode and casue should be written here?
Also, process excursion and failure mode cause are same thing?

The template guidance on failure mode and failure mode cause is given below:
"A potential Failure Mode represents any manner in which the process step identified previously could fail to meet the process requirements and/or design intent as described in the “Process Step Function / Requirement” column."

"Failure mode cause categories include, but are not limited to:
Machine
Material
Man
Measurement
Method
Environment"
 
Last edited:

Tidge

Trusted Information Resource
Perhaps this will help?

When I was confronted with (let's call them) "general manufacturing processes", examples include punching, welding, the approach I took was as follows.

1) I mapped (with the help of the operators) the general process flow, starting with set-up and ending with break-down. I took note of any ancillary processes, particularly those that may not be specific to any individual piece. Each process step became a section of the FMEA.

2) I conferred with operators asking simple questions like "why do you do this?" and "what could go wrong?". This helped me to figure out where to best put certain lines of analysis. For example: a failure in a setup step could result in a non-conforming part in a later step, but the analysis was much clearer if the risk controls implemented for the setup step are documented in the setup step, and cross-referenced in other steps as necessary.

3) In something like a cutting processes, I think it is legitimate to analyze the effects(*1) only at the step in the process where the cutting actually occurs. In other words: don't feel obligated explore all the effects of "parts don't match print" as failure modes in setup steps when you can leverage cross-references between FMEA sections.

(*1) Failure Effects of a machining process are going to be dominated by "part does not conform to specification". The specific ways ("failure modes") a part can be non-conforming may need to be spelled out... think of the classic "cut too much" and "cut too little".... depending on the failure effects. An example of different effects from a deburring process could be "too little -> sharp edges (because parts are not deburred)" "too much -> functional failure (because parts wont fit)".

It is also possible to have some other effects from machining processes that go beyond "outputs don't match the print", such as manufacturing materials (cutting fluids, chips) being present on the parts.

-----

Some foundation explanation of my approach follows.

Typically in the field of medical device manufacturing, the manufacturing process is NOT where the devices are "guaranteed to be safe and effective". The devices are supposed to be "designed to be safe and effective." It is far more common that a manufacturing process can result in individual devices that do not conform to the safe design, rather than being the process that guarantees a safe device (there are exceptions, such as sterilization) so the risk controls in manufacturing are almost entirely about avoiding the failure effects of "non-conformance to design".

I like to see all elements of manufacturing process (including setup steps for equipment) listed in Manufacturing Process FMEA because it makes it easier for inexperienced people to understand why certain things are done, as well as making it more obvious where risk controls/validation studies/control plans will be required (or offer the most bang-for-the-buck).
 

AndrewK

Involved In Discussions
How to align sequence of events in an Hybrid template of PFMEA and ISO 14971?
How to align sequence of events in an Hybrid template of PFMEA and ISO 14971?
How to align sequence of events in an Hybrid template of PFMEA and ISO 14971?
here are some hints form latest VDA-AIAG FMEA handbook for automotive industry. Maybe would be helpful to clarify what is cause and failure base on definitions.Color of colums is representing relevant linkage of information
 

d_addams

Involved In Discussions
Perhaps this will help?

When I was confronted with (let's call them) "general manufacturing processes", examples include punching, welding, the approach I took was as follows.

1) I mapped (with the help of the operators) the general process flow, starting with set-up and ending with break-down. I took note of any ancillary processes, particularly those that may not be specific to any individual piece. Each process step became a section of the FMEA.

2) I conferred with operators asking simple questions like "why do you do this?" and "what could go wrong?". This helped me to figure out where to best put certain lines of analysis. For example: a failure in a setup step could result in a non-conforming part in a later step, but the analysis was much clearer if the risk controls implemented for the setup step are documented in the setup step, and cross-referenced in other steps as necessary.

3) In something like a cutting processes, I think it is legitimate to analyze the effects(*1) only at the step in the process where the cutting actually occurs. In other words: don't feel obligated explore all the effects of "parts don't match print" as failure modes in setup steps when you can leverage cross-references between FMEA sections.

(*1) Failure Effects of a machining process are going to be dominated by "part does not conform to specification". The specific ways ("failure modes") a part can be non-conforming may need to be spelled out... think of the classic "cut too much" and "cut too little".... depending on the failure effects. An example of different effects from a deburring process could be "too little -> sharp edges (because parts are not deburred)" "too much -> functional failure (because parts wont fit)".

It is also possible to have some other effects from machining processes that go beyond "outputs don't match the print", such as manufacturing materials (cutting fluids, chips) being present on the parts.

-----

Some foundation explanation of my approach follows.

Typically in the field of medical device manufacturing, the manufacturing process is NOT where the devices are "guaranteed to be safe and effective". The devices are supposed to be "designed to be safe and effective." It is far more common that a manufacturing process can result in individual devices that do not conform to the safe design, rather than being the process that guarantees a safe device (there are exceptions, such as sterilization) so the risk controls in manufacturing are almost entirely about avoiding the failure effects of "non-conformance to design".

I like to see all elements of manufacturing process (including setup steps for equipment) listed in Manufacturing Process FMEA because it makes it easier for inexperienced people to understand why certain things are done, as well as making it more obvious where risk controls/validation studies/control plans will be required (or offer the most bang-for-the-buck).
This person manages risks!!

This is a masterful response.
 
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