In November 2017, the yellow print on FMEA alignment between AIAG (Automotive Industry Action Group) and the VDA (German Association of the Automotive Industry) was released after a three-year work phase. In the subsequent 90-day commenting phase, the VDA received 3,692 comments and objections, says Hans-Joachim Pfeufer, head of the working group. These were way beyond the working group’s original, tight schedule. The yellow print is scheduled for publication in the third quarter of 2019. Currently it is not known which consequences the objec- tions to its contents will entail. The following statements therefore refer to the yellow print in its current version as well as the VDA status report of February 2019.
Let’s start with the positive: For companies that create their FMEAs using a professional software solution in accordance with the existing VDA standard from 2006/2012, not much is expected to change. FMEA software providers are in contact with the FMEA consortium and for the most part have already prepared for the changes. They will bring their software updates to market shortly after the final standard has been released.
Discarding the risk priority number (RPN) and exchanging it for the task priority (TP) can certainly be considered one of the greater positive changes. Here, the aligned FMEA standard defines fields for Occurrence (O) and Detection (D) in dependence on Severity (S), in which further tasks can be categorized by “must”, “should” and “can”. Even if the definitions of the field are not directly comprehensible in individual cases, this is still a step in the right direction, a step some forward-thinking companies have already taken in similar ways.
Another positive item is the standardization of risk assessments and the applied tables. This was one of the reasons for starting the working group to standardize both standards in accordance with AIAG and VDA.
Last but not least, we must mention scoping, which has expanded the previous five steps required to create an FMEA in addition to a conclusive result documentation to a total of now seven steps. In the first step, scoping now allows companies to focus their FMEA application on developments and/or processes within which they expect effective correction measures. In this context, companies are currently developing risk filters that divide upcoming developments and/or process planning into “FMEA necessary”, “FMEA recommended” or “no FMEA”, based on self-defined logic.
A further big change is the way “Special Characteristics” are handled within the FMEA. Now, “Special Characteristics” no longer need to be mapped on the FMEA form during development. This item of the yellow print caused a lot of discussion. An inquiry with the head of the working group finally clarified the point: of course users can continue to use the De- sign FMEA to analyze “Special Characteristics” – but they don’t have to. Other systematic procedures are permitted as well. For Process FMEAs, on the other hand, the yellow print still has a small weak point. Here, the “Special Characteristics” in the FMEA form cannot be clear- ly allocated to the product or process characteristics. This, however, is an issue that will only affect software users to a small extent.
However, these positive items are opposed by an item that affects companies that still create their FMEAs in EXCEL. According to the current yellow print, in future these companies will have to depict the system’s structure as well as the function and failure analysis in the FMEA form. An FMEA form that contains these steps would then have 28 columns. Besides its elaborate and complex creation, these form-oriented FMEAs would have poor legibility.
Will companies now have to change all their FMEAs? No – once the new, aligned FMEA standards have been released, the following rules will apply: FMEAs that have already been started may be carried out using the old standard, whilst new FMEAs should use the new standard. If existing FMEAs have only marginal changes, the old standard can still be used in future. For greater changes, on the other hand, transitioning to the new standard is recommended.
For Design FMEAs, previously known as Product FMEAs, there are no severe changes compared to the previous VDA proce- dures. In many respects, the changes only refer to clarifica- tions and additions. Besides the known terms of function and the product characteristic, for example, the term purpose (e.g., bonding, sealing) has been introduced and the requirements have been divided into requirements that can be functional- ly influenced (e.g., switching time) and those that cannot be functionally influenced (e.g., resistance to vibration). Further- more, the interfaces have been divided into physical, material, energetic and information technological interfaces.
One important clarification affects the risk assessment catalogs and concepts. In addition to the end customer, Se- verity now also takes the fields of production and assembly into account with their own assessment table. When assessing the end customer, the graduation of the S value is based on the criteria Safety (S=10), Laws (S=9), Main Function (S=8- 7), Convenience Function (S=6-5) and the appearance, haptics and optics (S=4-2). Especially the latter should enable users to obtain realistic S-assessments once more.
A differentiated view has also been taken with regard to the Occurrence assessment table. Here, in addition to prob- abilities on occurrence across the life cycle, assessments can now be evaluated by experience and the presence of suitable preventive actions. When evaluating Detection, a new concept has additionally been introduced that allows improved allocation between preventive actions and controls detection. All actions carried out up to sample status (e.g., simulation, FEM calculation) are seen as preventive actions. Actions that describe a test with an existing sample are evaluated as controls detection. This now clarifies that design reviews do not depict controls detection. Now, only the table for evaluating Occurrence contains a slightly more general wording, which does not allow clear classifications.
When it comes to Process FMEAs, the changes are predominantly positive. Once again, in many respects these refer to clari- fications and additions. Compared to VDA’s previous focus on all process steps within the work plan, the yellow print now provides a decisive clarification by focusing on the value-added process steps. Going forward, this focus intends to prevent meaningless root causes such as “Worker error” with the ineffective actions “Worker train- ing” and “Worker self-inspection” from appearing in Process FMEAs. A further clarification concerns the product characteristic (Error Level), which is created in the process step, as well as the process characteristic (Cause Level), which is necessary to create the former. This clarification allows the control plan to be better and logically connected to the Process FMEA.
In future, the Severity evaluation can be differentiated via three assessment categories by end customer, supplied plants and own plant. Here again, a new concept has been introduced that allows improved allocation between preventive actions and controls detection. Here, any action that prevents faulty manufacture of a product characteristic is defined as a pre- ventive action (e.g., operator inductions, machine capability). Any action that enables the detection of product characteris- tics that have been defectively manufactured (e.g. via sensory inspection, dimensional inspection or visual inspection) is defined as a detection action. This also takes the time of detection into account (in manufacturing processes or subsequent processes). Unfortunately, the new assessment tables for Occurrence and Detection in the yellow print contradict the well comprehensive concept in a couple of places.
The assessment tables for Occurrence O and Detection D in the Process FMEA are rather general, which gives cause for further discussion. Their global description no longer allows us to make a precise assessments of errors, such as: ”This error will occur once for every 500 actions and of 1,000 faulty units, only 3 will not be detected.” Here it is recommended to integrate an additional column with ppm values and % values into those assessment tables that orient themselves on the previous VDA assessment tables (1996 and 2006). This allows users to determine a more precise evaluation of the average outgoing quality (NOK parts “slipping through”) to the customer.
In future, reducing the scope of the document would be preferable. With 223 pages as of this moment, the current yellow print has two to three times as many pages as the ground- breaking FMEA volume published in 1996. This makes it challenging to incorporate the information for the increasing number of persons interested in FMEA. It may have made more sense to publish the additions for Mon- itoring and System Reactions (FMEA-MSR) in a separate volume on FMEA within the scope of Functional Safety. As a whole, the positive aspects of the new FMEA standard in accordance with AIAG/VDA outweigh the negative. For EXCEL users, however, these changes mean greater adaptations, which will surely cause the question of whether to purchase an alternative software solution to resurface. It remains to be hoped that small inconsistencies within the yellow print will be resolved by the time the final edition is released.
As the Senior Expert at the Fraunhofer Institute for Manufacturing Engineering and Automation IPA in Stuttgart, Dr. Alexander Schloske is responsible for methodical product and process optimization using FMEA as well as securing mechatronic systems under the aspect of functional safety.
The wait is almost over: The final approval of a uniform standard by the two large automotive associations AIAG and VDA is imminent, a fact we very much welcome. Especially for those of you that deliver to American as well as German manufacturers, this will be sure to simplify your FMEA process. What can we do for you in this process?
For some years, Babtec FMEA has been aligned with the VDA’s systematic approach model, meaning we can use this as the base on which to build the relevant expansions to depict the aligned guidelines. Based on the yellow print, we have already identified which changes and upgrades we will need to make to our FMEA module – and we have already designed the necessary work packages. As soon as the new guideline has been approved and released, we will check these designs for possible modifications and start the implementation in our software.
As usual, we will create the new, standardized risk assessment catalogs for S, O and D for you and deliver them in a new version of BabtecQ. This will give you the additional op- tion of adding your own, product-specific examples that aim to support your FMEA users in selecting the right assessment in individual cases, as requested. The new task priority (TP) is determined on the basis of the known assessments for S, O and D and will help you prioritize identified risks. This is based on an extensive matrix with every possible com- bination and explanations that have been structured logically. Naturally, you will find this matrix within the software in future. Once you have determined the Task Priority, this will indicate which of the identified risks you absolutely must or should reduce by introducing suitable actions.
For us, it is important to ensure that your previously released FMEA versions remain unchanged. In addition, you will be allowed some practicable leeway for the transition to the new guideline. That is why we will pro- vide the new assessment based on the Task Priority in addition to the previously available assessment options (RPN, GYR Factor and Risk Matrices). This will enable you to use both RPN and TP for your decisions in existing FMEAs. Of course, you will still be able to store your own specifications for risk assessments that have been aligned with your products and manufacturing processes. This means that the Babtec FMEA will still be your FMEA tool if you are active in a sector outside of the automotive industry.
Once the guideline has been released, we will make the final decision on how to handle the labeling of special characteristics based on our characteristics class. To ensure that information on a product characteristic is consistent within the Babtec software, it will certainly make sense to maintain the existing marking in the Design FMEA. It will be chal- lenging to create the FMEA form defined in the guideline (yellow print) with its multitude of additional columns in such a manner that the content of your FMEAs can be displayed legibly. We continue to wait in suspense for the release and what it may bring. How about you?