Aspects in the FMEA Grid

Structure analysis (step 2)

The purpose of Structure Analysis is to identify and breakdown the manufacturing process and is intended to represent the process flow as it physically exists. It provides the basis to the Function Analysis (Step 3)

Process Item

The Process Item of the PFMEA is the up most level of the PFMEA.  In AVIX this is always an assembly Line. 

Process Step

The process step is an work station or a manufacturing operation. It is also considered to be the focus element of the PFMEA. In AVIX the process step and the focus element is separated. The process step is the Workstation and the focus element is the Process Task.

Process Work Element

The Process Work Element is the lowest level of the process structure tree. Each work element is a potential cause that can impact a process step, or process task and should be considered separately during the FMEA. Each work element corresponds to a category, commonly used in Ishikawa causality diagrams and populated by lean manufacturing as 4M or 5M. 

Example categories:

Function analysis (step 3)

The process function analysis ensures the that functions and requirements of the product/process are  taken care of. It provides the bases of the failure analysis (Step 4)

About Functions

A function describes what something is intended to do. A process item or process step can have multiple functions.

Before the function analysis can be done product and process functions / requirements needs to be known. This can be gathered prior or during the analysis.

The description of a process function should to be clear and, if possible,  phrased with a verb and an noun like: "Positioning rear window" or "Fasten seat"

Function of the Process Item

A high level function that references the Process Item in the Structure Analysis. It can take into account functions such as:

• Internal function
• External function
• Customer and/or end user function

The negation of the process item functions will be the Failure effects in the Failure analysis (step 4)

Example: "Assemble front seat"

Function of Process Step

The Function of the Process Step describes the resulting product features produced at the workstation or by the process task

The negation of the process step functions will be the the Failure modes in the Failure analysis (step 4)

Example: "Fasten the seat with screws"

Function of Work Element

The Function of the Process Work Element reflects its contribution to the Process Step (Process Task) to create the process / product features.

The negation of the work element functions will be the the Failure causes in the Failure analysis (step 4)

Example: "Enter the screws into the threaded holes"
or
Example: "Tighten the screws with the right torque"

Failure Analysis (step 4)

 

1. Failure Effects (FE)

Severity

2. Failure Mode of Process Step

3. Failure Cause of the Work Element

Risk analysis (step 5)

Current prevention control (PC) of FC

Occurrence

Current detection control (DC) of FC

Detectability

Action priority