The 7 steps of FMEA according to the VDA/AIAG harmonization

Step 2 of the standardized FMEA method description:

Summary: Structural analysis

The individual elements of the FMEA are identified and arranged in the structural analysis, which is the 2nd step of the FMEA according to the standardized FMEA method description. In the design FMEA, these are the systems, subsystems, components and parts of the technical risk analysis. In the process FMEA, they are the process elements, process steps and causal elements. Overall, the 2nd step of the FMEA according to the standardized FMEA method description is the starting point for the functional analysis (link to step 3). This can only begin when the structural analysis has been completed.

The objectives of the structural analysis are:

• Graphical representation of the scope of observation
• Creation of a structural tree, boundary diagram or digital model (D-FMEA) or of a process flow chart (P-FMEA)
• Definition of the structural interfaces and interactions (D-FMEA) and the process steps and sub-steps (P-FMEA)
• Clarification of the interface responsibilities in the interaction between customers and suppliers.

Process flow charts or structural trees are the graphical basis for the structural analysis. They help to define the process, although the format can vary depending on company and project.

Detailed knowledge: Structural analysis in the D-FMEA method description

System structure in the D-FMEA

The structural analysis in the D-FMEA reflects the scope of observation and complexity of the structures. Depending on the scope, the structural analysis includes hardware and software elements and may be subdivided into several work packages to provide a clear representation. The D-FMEA analysis is subdivided into two customer categories: end users and assembly/production. The better the knowledge of these two customer categories and their requirements, the more robust the definition of the functions and specifications and of any possible errors will be in the structural analysis.

Structural analysis of the D-FMEA:Block/boundary chart

The graphical representation of the system structure is an important part of the standardized method description. It helps with the detailed creation and understanding of the structural analysis. The methods used most frequently are:

• the block/boundary chart (more about boundary charts under ProfessionalArticles)
• the structural tree (see P-FMEA)

Detailed knowledge: Structural analysis in the P-FMEA method description

Process flow chart in the P-FMEA

In the context of the structural analysis in the P-FMEA, the process flow chart is essentially a tool for inputting the structural analysis. In the end, the chart represents the entire flow of parts in production – from the incoming check of the parts, through their transport routes to the various assembly stations and individual production steps, to the final check of the parts and their shipment to the customer.
Structural analysis of the P-FMEA: Structural tree

The elements previously examined in the process flow chart are organized hierarchically in the structural tree. In addition, existing interactions and any structural connections are examined more closely and illustrated graphically at this point in the structural analysis. The aim in drawing up the structural tree is to improve understanding of the various types of relationships between process objects,process steps and causal elements in the overall context of the standardized FMEA method description. The product (part) is presented at the top level, together with the effect of the individual process steps or stations (elements) and the 4 Ms that make up the causal elements: man, machine, material, measurement.

Structural analysis of the FMEA: Interface responsibilities

The result of the structural analysisis a clear visualization of the entire process flow for everyone involved in the FMEA process. It is therefore an important tool in the interaction between suppliers and customers. On the basis of the structural analysis, technical issues in development (D-FMEA) are dealt with and reviews of the process design (P-FMEA) and of the entire FMEA project are carried out.

Thanks to clearly defined information, the structural analysis is the starting point for the functional analysis in the 3rd step of the standardized method description, which builds on it 1:1.Work steps that are not included in the structural analysis are therefore ultimately omitted from the functional analysis.