Definition
A branch of FMEA that progressively identifies potential failure modes, effects, and causes during the manufacturing or service process design phase, and uses risk assessment and preventive controls to reduce the probability of process failures.
In detail
PFMEA focuses on 'how the process might fail during execution,' such as missing parts, incorrect assembly, parameter loss of control, or inspection omissions; DFMEA focuses on failures inherent in the product design, and the two cannot be interchanged. PFMEA should follow the actual process sequence, convert high-risk items into mistake-proofing, process control, standard work, or control plans, and re-evaluate risk after actions are implemented. Merely filling historical defects into a table without modifying process control does not constitute an effective PFMEA.
Example in practice
When a new assembly line was preparing for mass production, the team reviewed each process and found that bolt torque might be insufficient due to incorrect tool program selection. The PFMEA recorded the customer consequence, cause, and existing detection method for this failure, then added program poka-yoke, automatic torque recording, and abnormal machine lockout, and wrote the control requirements into the control plan before re-scoring.