Causes at the system level are cascaded as failure modes in more detailed analysis. These can be derived from pre-work documents such as Boundary (or Block) Diagrams, Parameter (P) Diagrams and Interface Analysis. The causes at a component level can be related to the material properties, geometry, dimensions, interfaces with other components and other energies which could inhibit the function. The causes should be determined at the physics-level. DFMEA Section 2 (Quality-One Path 2) Potential Causes / Mechanisms of FailureĬauses are defined for the Failure Mode. The Classification column designates where the characteristics may be identified for Process FMEA Collaboration. These special characteristics typically require additional work, either design error proofing, process error proofing, process variation reduction (optimized Cpk) or mistake proofing. Many types of special characteristics exist in different industries. ClassificationĬlassification refers to the type of characteristics indicated by the risk. If a recommended action is identified, it is placed in the Recommended Actions column of the DFMEA. Actions may be identified to change the design direction on any failure mode with an effect of failure ranked 9 or 10. The highest severity is chosen from the many potential effects and placed in the Severity Column. 9-10: Regulatory and / or Safety implications.7-8: Degradation or loss of the primary function of the item studied.5-6: Degradation or loss of a secondary function of the item studied.2-4: Annoyance or squeak and rattle visual defects which do not affect function.The severity ranking is typically between 1 through 10 where: The Severity of each effect is selected based on the impact or danger to the end user / customer. All effects should appear in the same cell or grouped next to the corresponding failure mode. Many effects could be possible for any one failure mode. The effects of a failure on multiple customers are listed in this column. Failure Modeįailure Modes are the anti-functions or requirements not being met. The first opportunity for recommended action may be to investigate and clarify the requirements to prevent wasted design activity. If requirements are poorly written or nonexistent, design work may be wasted. The requirement must be measurable and should have test methods defined. The requirements are either provided by a document or are converted from a process known as Quality Function Deployment (QFD). The requirements, or measurements, of the function are described in the second column. There may be many functions for any one item. The function is the “Verb – Noun” that describes what the item does. The item can be a complete system, subsystem or component. The Item / Function column permits the Design Engineer (DE) to describe the item that is being analyzed. The Design FMEA form is completed in the following sequence: DFMEA Section 1 (Quality-One Path 1) Item / Function The DFMEA is completed in sections at different times within the design timeline of the project, not all at once. Each section has a distinct purpose and a different focus. There are five primary sections of the Design FMEA.
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How to Perform Design Failure Mode and Effects Analysis (DFMEA)