Robot with DFMEA

DFMEA – Design FMEA, Definition and Example

1. What is DFMEA?

DFMEA (Design FMEA) is a type of FMEA (Failure Mode and Effects Analysis) that focuses on the design of the product to reduce the risk of the product failure. In other words, Design FMEA is an analytical methodology used in design process to improve product quality.

The DFMEA document (worksheet) is also referred to as DFMEA. See an example of DFMEA document in the next section.

DFMEA Timing With APQP Chart
Position of DFMEA in Project Management

2. DFMEA Example

Take a look at DFMEA example of a ballpoint pen which is familiar with all of us. As any other DFMEA, this example has 2 parts: Header and Body.

DFMEA Example Form

2.1 DFMEA Header

General information: includes but not limitted to: product name, product number, team member, project leader, customer, document number, document version,..

2.2 DFMEA Body

Body content: includes many columns of analysis. We have some DFMEA templates but are no general requirement for the columns (except if you have to follow customer requirements), but minimum requirement of DFMEA should includes below information:

DFMEA Example Ballpoint Pen
DFMEA Example – Ballpoint Pen

Design Failure Mode and Effects Analysis is a structure analysis, it has a relational structure between its columns

  1. Items / Function: Item (component, part) of the product to be analyzed. And it functions. An Item has one or many functions. In this example, pen tip has only one function. If an item has many functions, functions can be listed in a separated column.
  2. Requirement: respective requirements of the function. A requirement has one or many potential failure modes.
  3. Failure Mode: (or Potential failure mode) The way that item potentially fails to meet the requirement. A failure mode has one or many potential effects.
  4. Effects: (or Potential effects) Effects of the potential failure mode on the function and customers.
  5. Severity (S): a ranking number reflects the most severe potential effect of a failure mode. Severity ranks on a 1 to 10 scale, 10 is the most severe risk.
  6. Class: Special product characteristic or high risk failure mode.
  7. Cause: What allows the failure mode to occur. A failure mode has one or many potential causes; the potential causes should be separate from each other but still aligned with its failure mode.
  8. Prevention Control (in Control Method): is a design control method for preventing potential cause to occur.
  9. Occurrence (C): a ranking number reflects the possibility of occurrence of the Failure. Occurrence ranks on a 1 to 10 scale, 10 means the highest possibility of occurrence.
  10. Detection Control (in Control Method) is a design control method for detecting the cause or failure if it happens.
  11. Detection (D): a ranking number reflects the best detection control method. Detection ranks on a 1 to 10 scale, 10 means worst detection capability.
  12. RPN: (stands for Risk Priority Number) An indication number to evaluate the risk of the process based on Severity, Occurrence, and Detection. Depend on RPN and S, O, D indexes, the responsible team/individual has to decide corrective action needed for each failure mode. RPN formular is: RPN = S x O x D
  13. Action: Corrective action to eliminate or reduce the chance of the causes of failure mode.
  14. Responsibility: Person/Department who has a responsibility to complete the corrective action.
  15. Target Finish Date: The plan completion date.
  16. Actual Finish Date: The actual completion date.
  17. Severity: re-rating severity of failure mode after corrective action
  18. Occurrence: re-rating occurrence possibility after corrective action
  19. Detection: re-rating detection capability after corrective action
  20. RPN: re-calculate Risk Priority Number after corrective action

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3. DFMEA vs PFMEA

Design FMEA and Process FMEA have the same methodology (FMEA), the main difference is objective. While DFMEA focuses on design problem, PFMEA focuses on process problem.

However, DFMEA should cover all the potential failures that can occurs in the production if the failures are result of a bad design. For example: a wrong part is assembled because it has the the similar shape with the correct part. If DFMEA cannot eliminate or reduce the risk of these failures (by applying poka-yoke in design for example), PFMEA should take care.

4. Why use a Design FMEA?

Quality is critical to satisfying your customers and retaining their loyalty and keep them continue buying the product. A lot of recent quality scandals with many companies show the fact that serious design problems can ruin the reputation of any company or put them out of business. Less serious design problems can dissatisfy customers, delay launching of new product and place a substantial financial burden on the company.

5. Team for Design FMEA

A good Design FMEA need to be conducted by cross functional team and led by the product design responsible engineer. The involved departments should include but are not limited to Design, Testing Analysis Engineer, Production, Supplier Quality, Product Quality, Service and Logistic.

DFMEA Team Organization Recommendation for DFMEA Team Organization

6. When to conduct a Design FMEA

With Design FMEA, designers can ensure that all design requirements are completely met before start the production or continously improvement.

6.1 When to start

For a new product, Design FMEA should start with product design and before prototype manufacturing.

6.2 When to review

The team should continuously review and update DFMEA document in the events of product changes:

  • Change of Product Design: Change product dimension, the material could be the reason to review DFMEA. In this case, the change point and effected points should be focused.
  • Quality Problem caused by product design: New internal defects or customer return should be reflected in DFMEA to re-analyze and re-evaluation and consider for corrective action.

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DFMEA should reflect the current status of product design, and that is why it is called a living document. However, keep DFMEA “living” is not easy. That’s because of a complicacy of DFMEA and its linkage to other documents, maintaining DFMEA living is much easier if we use proper DFMEA software.

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