No matter how useful or well-written a standard, guideline, or instruction is, there are often shortcuts, or “tricks,” to its efficient utilization. In the case of the aligned AIAG/VDA Failure Modes and Effects Analysis method, one trick is to use visual Action Priority tables.
In this installment of the “FMEA” series, use of visual tables to assign an Action Priority (AP) to a failure chain is introduced. Visual aids are used in many pursuits to provide clarity and increase efficiency. Visual AP tables are not included in the AIAG/VDA FMEA Handbook, but are derived directly from it to provide these benefits to FMEA practitioners.
In Design and Process FMEA, Action Priority is comprised of three components: Severity (S), Occurrence (O), and Detection (D), as described previously in the series (“Vol. VI: DFMEA” and “Vol. VII: PFMEA”). Each Action Priority in DFMEA and PFMEA is assigned according to a single AP table, reproduced in Exhibit 1.
Severity, Occurrence, and Detection are each scored on a 1 – 10 scale. Every possible combination of S, O, and D scores can be viewed as a position within a cube of 10 units per side. The AP table of Exhibit 1 is presented in cube form in Exhibit 2.
In this form, information contained within the cube is not easily extracted. An interactive program could be developed to section the cube (or navigate the original AP table) based on S, O, and D inputs. The effort to do so may be excessive, however. Alternatively, a set of static section views can be created for quick reference. One such set is provided in the supplement shown in Exhibit 3.
The sections of the “AP Cube” presented in Exhibit 3 are taken along the Severity axis, following the logical sequence of FMEA development. Sections could also be taken along the Occurrence and Detection axes, should these be deemed useful.
To use the sections in the supplement, simply locate the view corresponding to the failure chain’s Severity score, as indicated at the top of each view. In that view, locate the column corresponding to the Occurrence score and the row corresponding to the Detection score. The color of the square at the intersection of these identifies the Action Priority to be assigned to the failure chain.
For rapid visual capture of the information needed, each Action Priority is identified by a color code, as follows (see Legend in supplement):
In Supplemental FMEA for Monitoring and System Response (FMEA-MSR, see “Vol. VIII: Monitoring and System Response”), the three components comprising the Action Priority are Severity (S), Frequency (F), and Monitoring (M). The AP table for FMEA-MSR is reproduced in Exhibit 4.
Construction of a cube and subsequent sectioning is done in the same manner as that for Design and Process FMEA. The resulting visual AP tables are provided in the supplement shown in Exhibit 5. Use of the supplement and the color code utilized are also consistent with Design and Process FMEA.
The observant reader will quickly notice something amiss in the visual AP tables for FMEA-MSR – the S = 9 and S = 10 tables appear to be reversed. The visual representation is consistent with the original (text) AP table (Exhibit 4), however. This is a logical breakdown in the Supplemental FMEA; practitioners must be aware of it and extremely cautious when using the S = 10 portion of the table or visual aid. Thorough justifications should be documented for Low and Medium APs assigned that were not available in the S = 9 table. Use of the S = 9 table is less risky because it sets higher priorities than may otherwise be required.
For additional guidance or assistance with Operations challenges, feel free to leave a comment, contact JayWink Solutions, or schedule an appointment.
For a directory of “FMEA” volumes on “The Third Degree,” see Vol. I: Introduction to Failure Modes and Effects Analysis.
[Link] “FMEA Handbook.” Automotive Industry Action Group and VDA QMC, 2019.
Jody W. Phelps, MSc, PMP®, MBA
JayWink Solutions, LLC
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