A way to better assess process risk? – enhanced PFMEA

The typical approach to a process FMEA analysis limits us to looking only at causes that relate only to product quality, and it may be worth looking at causes in a broader context. How can this be done and what can be the benefits?

A basic approach to working with PFMEA

Standard PFMEA analysis refers to the risks associated with the appearance of nonconformity (defect or failure). By nonconformity, we mean the failure to achieve the intended characteristics of the product.

Examples of non-compliance in PFMEA:

• for cutting – length not in accordance with specifications;
• for hardening – hardness below specifications;
• for injection molding – product geometry not in accordance with specifications;
• for paint shops – inclusions on the surface of the product.

Then, for these nonconformities, we must find all possible causes to minimize the associated risks.

What does it look like in practice?

Below is an example of a basic PFMEA analysis:

Fig. 1. Example of a basic approach to process FMEA analysis. Source: own development in PQ-FMEA+ software

Let’s focus on the above phase of the process. The important task of the worker is to turn off the dust collection system (while not performing the task will not affect the quality of the product), so we do not analyze it. For the external customer for whom we supply the product, this is not a problem either, because the quality of the product is not at risk, so, again, we will not analyze this.

It is worth noting here that this approach focuses only on the reasons relating to the quality of the product. Here we do not take into account the many activities necessary in the process (e.g., those related to ensuring safety).

Expanded approach to working with PFMEA

The risk analysis should take into account safeguarding our interests (and not just guaranteeing passage of the audit). So it would be worthwhile for the PFMEA to cover all the risks the company might encounter. Especially since it doesn’t require a lot of time, since we are already dissecting and analyzing each phase of the process anyway.

Below is what the same example would look like in a broader context (just expand the green structure a bit).

Figure 2: Example of extended process analysis. Source: own development in PQ-FMEA+ software.

We have added a function to the process phase called “Ensure process safety”, which will force the indication of an action to shut down the dust collection system.

The nonconformity that will appear in the next step is “Failure to ensure the safety of the process” and its cause will be “The operator did not turn off the dust collection system”.

Then all you have to do is analyze:

• what can be done so that the operator does not skip this step (maybe automation)?
• would we detect such a situation and how?

An analogy can be made with process efficiency analysis (e.g., maintaining productivity at the analyzed position). Here, too, we can begin to analyze those activities of the employee that will not impair the quality of the product, but will slow down the analyzed process.

And how to do it in practice?

Often the analysis we do is also presented to external clients, so how do we conduct an extended PFMEA without showing our internal security topics to clients, and not creating multiple documents.

Here it is worth using the column added to the AIAG & VDA form “Codes for filtering”. All you need to do is set the appropriate designation, e.g. “B” is safety problems that are not related to product quality and then with one click you can filter only those risks you want to show to an external customer.

Summary

PFMEA can prove effective in improving quality as well as safety (EHS) and efficiency (Lean/Kaizen context). You just need to know how to use them.

For more on building tree structures in PFMEA, see the article: https://pq-fmea.pl/podsumowanie-podejscia-7-krokow-w-analizie-fmea-wg-aiag-vda/ or our training courses, among others.