PFMEA - CNC machining


It's a good start, but be careful you do not get repetitive.
In your machining section, you have failure modes "wrong dimension" and "wrong depth" for example. Is not the depth a dimension? I can see surface finish being different as that is very sensitive to speed/feed.
But from the snippet, I like it. It's addressing what the PROCESS can do wrong and how to detect/react to it.
You are of course right. Depth is also a dimension

My next problem will be the Control Plan.
As I wrote in my first post, my company used a “FMEA” with ALL dimensions on the drawing.
This was extremely time consuming for the FMEA team, but very convenient for the Control Plan team as they were served with which dimensions to check, with what measuring device/gauge how often and so on.

In this new and more correct PFMEA the input to the Control Plan will be how to measure/control the wear of the tools (life span), the cutting fluid temperature, feed etc.
Not “Measure this thread with an M16 gauge”.
(With the exception of the Special Characteristics?)

I can already hear them asking, "But how will we know what dimensions to measure!!?"


Quite Involved in Discussions
Design FMEA could be one of basic core of PFMEA & C plan ; the engineering drawings & Specific requirements will indicate the critical & the priority ; the severity &relevant function /safety could be focused on in DFMEA " -- the outputs of both will be inputs & refenced in the generated C plans & relevant inspection , test & work instructions


Involved In Discussions
Thank you all for your response and input. It really helps!

We will be using the AIAG-VDA take on PFMEA.

The FMEA software we are working with is somewhat adjusted to the new format of AIAG-VDA, but not fully and I think this confuses me sometimes.
In the software, the “Potential Causes” are split up in the 4Ms.

As for the Failure Mode in my draft the Failure Causes could be;
Man: Part incorrectly placed by the operator
Machine: The fixture’s guides/support surfaces are damaged
Material: Defect cast references
Environment: Bad lighting

Or do you mean a different breakdown? English is not my native language, so there is always a risk of misunderstanding
you are correct, yes. Basic draft is good, I was trying to say that by having 4m there will be a lots of causes depending to requierement for each 4m element.
For example Function/requierement for MAn element is - Place part acc. to Wor kinstruction/ FC might be -FC1: Not placedat all, FC2: Incorrectly placed, and so on.


Starting to get Involved
I can already hear them asking, "But how will we know what dimensions to measure!!?"
If you really want to go with a family control plan, you handle the dimensions by referring to a different document that contains the part specific measurements to make. You can call this a "Quality Plan" and "Inspection Map" whatever you like.
It MUST be controlled by your QMS so that it has a distinct document number.
It should also be part specific (obviously).
Thus, you family control plan has on it "Dimensional Check" and it is controlled by "Specific Part Quality Plan"

In this way, the Quality Plan becomes more of a map with images and specificiations of key measurements which is easier to post on the floor without a book. Simpler to train on, etc.



I´m handling a different process, but i think i´m in the same problem-state. We are currently migrating from ISO 9001 to IATF due to receiving a relocation of some plastic-molding parts from another site of my company.

Now we got their documents and they made a control-plan for every plastic part, but they are very repetetive except sc-characteristics. In the past we here didn´t use control-plans but we have an general Plastic-molding PFMEA. I already included in this pfmea an general control plan for single component plastic parts, for example incomming inspection of plastic material is always the same, even if the specific material differs from part to part. In the post before it was mentioned that there would be a possibility to do an additional "specific part quality plan".

Does anybody have an example for an family control-plan and one part specific appendix? That would reeeeeeally help me.



i have tried to build something like it was mentioned in this thread. I´m aware that this FMEA is not according to actual AIAG standard. I just used an old FMEA to try to do an discussion baseline example.

I´m not shure how it will be identifiable here but lets see

Process Flow first step:
1.0 Warehouse

1.1 Raw material incoming inspection
1.2 Silo filling – silo-train
1.3 Silo filling - bagged goods
1.4 Shelf provision - bagged material
1.5 Dryer filling - octabin

1.1 Raw material incoming inspection
1.1.1Comparisation Delivery Note with Order DocsWrong material deliveredMaterial not usable - unplanned production stop6Supplier-error1Order-process controlled via SAPComparisation Delivery Note with Order Docs636
1.1.2Optical inspection of the deliveryOptical deficiencys like broken/damaged bags, Material impurities etc.Material in parts not usable - unplanned production stop4Supplier-error2Optical inspection of every delivery and documentation on delivery note648
1.1.3Material quality - retention samplingSampling not doneSample not available in case of quality problems6Incorrect operation / inattention in manual process2Material specific quality plan mentions samplingOptical inspection of every delivery and documentation on delivery note672
1.1.4Material quality - check of material certifiquateParameter out of toleranceMaterial cannot be used6Supplier-error2Material specific quality plan mentions checkingCertifiquate is checked on every delivery and compared to the material specific Q-Plan672

PFMEA Reference NumberTeile / Prozess-step
Part / Process-Step
Name of process/
process definition
Machine, device, equipment
Production tool
No.Prozess-hauptmerkmale /
Hauptmerkmale /
Special Char. ClassProdukt / Prozessspezifikation, Toleranzen , Zielwerte /
Product-, Processspecification, Tolerances
Prüfmethode, Prüfequipment /
System of control and measuring
Anzahl /
Prüfintervall /
Test-InstructionReaktionsplan und Korrektivmaßnahmen
1.0 Warehouse
1.1 Raw material incoming inspection
1.1.1Comparisation Delivery Note with Order DocsWorkerDelivery Note / Purchasing OrderRaw material identityMaterial identity matching orderMaterial correct according to material specific Q-Plan1Every deliveryMaterial-specific Q-PlanQRQC-process, information to WEP-Dept. to create complaint report
1.1.2Optical inspection of the deliveryWorkerProduct label and packagingProduct-labeling, packaging undamaged and according to order documentCheck material and packaging for integrityMaterial undamaged according to material specific Q-Plan
(max. weight and container can be different, if defined accordingly in the order specification)
1Every deliveryRaw material-specific Q-Plan Goods income inspectionQRQC-process, information to WEP-Dept. to create complaint report
1.1.3Material quality - retention samplingWorkerRaw material qualityRaw material opticsMaterial without impuritiesoptical inspection1Every deliveryRaw material-specific Q-Plan Goods income inspectionQRQC-process, information to WEP-Dept. to create complaint report
1.1.4Material quality - check of material certifiquateWorkerRaw material qualityRaw material certifiquateMaterialcertifiquate according to material sepcific Q-PlanComparisation Q-Plan Material certifiquate1Every deliveryRaw material-specific Q-Plan Goods income inspectionQRQC-process, information to WEP-Dept. to create complaint report

Benennung:Sumikasuper E 4008 naturZeichnungsnr.:Lt 242.16.910
Manufacturer:BASF LudwigshafenME/LE:Silo-Train or Octabin
Q-Plan raw material goods income inspection:
Material Ident CheckSumikasuper E 4008 natur
Check material and packaging for integrityUndamaged
Retention samplingSample in storage area
Check material certificate
Specific Gravity 1.68 -1,72
Flexural Strength min.120 MPa
Flexural Modus min. 10 GPa
DTU2 (1.82 MPa) min.300 C°
Flow Temperature 345 – 360 C°


Registered Visitor
I am very well versed in your process and have reviewed at least 500 PPAPs that are exactly that: HPDC+Machining+Assembly in some form.
Some folks put EVERY dimension in the FMEA & Control Plan, some do not.

My preference is to NOT put every dimension in as a failure mode. Here are the reasons:
1) If you put every dimension in, your are burning too much time making sure every dimension is in there. And not enough time focusing on the actual failure modes.
2) You will be constantly redoing your PPAPs every time any dimension changes. Even if the dimension doesn't change, but you find statistically that at some point after SOP you change your guard bands, well, your control plan changes and you have to PPAP again.
3) You will hamstring yourself with executing proper read across / lessons learned. What I mean is if you learn through a corrective action that you had a PFMEA problem, you will have a mountain of work to change paperwork where a more generic PFMEA is easier to change. I'll honestly take a shop with a robust lessons learned program over a shop with fully detailed PFMEAs any day of the week as a customer.

I could go on, but those should be enough.

Take your machining center, any machining center, and the failure modes are generally:
1) Problems caused by clamping (deforming the part)
2) Problems caused by tool wear
3) Problems caused by tool breakage
4) Problems caused by misloading
5) Problems caused by debris on the fixture
6) Temperature problems (coolant temperature changing, changing the temp of the part)
7) Uncontrolled changes to program
8) Casting problem: bent / missing clamping points or datums
9) Casting problem: heat check / flash on the datums cocking the part
10) Casting problem: missing cast material resulting in non-cleanup
11) Improper tool loading
12) Improper setup

These are the failure modes. Not "this ID is out of spec" then "that ID is out of spec." If you sent me a part with "this ID" out of spec and your root cause was "I made the ID out of spec," I would reject your 8D. If your root cause was "The chiller went down for a shift and the coolant got to warm." THAT's a root cause.

Come up with your own list of how the machining operation fails, not the dimension, and PFMEA how you will check for and control THIS.
Will you need a job specific dimensional sheet with dimensions, limits and gaurd bands? Yes. Your PFMEA should refer to this being a thing that exists, but that's your process specific sheet which may be changed as you run your process. This is in order to protect MY print. Folks tend to forget that you CAN adjust your process to keep the dimensions centered and in control. Don't tie your hands to do this by specifically putting all this in the PFMEA.

On to the Key Characteristics: THESE should be specifically called out in your PFMEA because I have told you they are critical to my unit functioning.

The smart strategy is:
1) Make a generic master PFMEA and Control Plan "block" for your HPDC, your machining and your assembly.
2) Now you make a process for my part. Let's say it takes 3 machining operations. You point to your casting block once, then your machining block 3 times. (After all, your list of machining failure modes should be universal.)
3) You then add in where appropriate my Key Characteristics at the points where they are made AND checked.

Now, you make an error and in your corrective action you need to change your master FMEA. If it's a worthwhile change, you change your MASTER block, and it cascades down to all your other blocks.

A strategy like this will let you focus on what's different from the norm in any new job, instead of burning daylight doing repetitive paperwork on the things that are standard.
Would you happen to have a PFMEA & Control Plan structured that way that you could share? We generally addressed all characteristics on the print and how we were controlling them. Thanks for your help


Registered Visitor
Thank you! I could not agree more :)
My absolute goal is to create generic PFMEAs for our main processes.

I just wrote down a very quick draft in excel (not in any way complete) just to get your opinion if we are on the right course?
Or is it too simple?

View attachment 29612

And of course we will also discuss and find the preventive and detective process controls and a SOD assessment.
Julia would you share that PFMEA and Control Plan for machining
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