Step by step procedure for implementing a FEMA of a product

By
On:

FMEA ProcedURE

The basic steps for implementation of a FMEA are outlined below.

1.Describe the product/process and its function.

2. Create a block diagram of the product/process: The block diagram shows the logical relationships of components and establishes a structure around which the FMEA can be developed.

3. Complete the header of the FMEA form worksheet: Item, Design/Process responsibility (i.e., team leader), Prepared by, Model number/Year, Key date, Core team (i.e., team members name), and Revision date . Modify these headings as needed.

4. List product/process functions.

5. Identify failure modes

A failure mode is defined as the manner in which a component, subsystem, system, process, etc., could potentially fail to meet the design purpose.

Examples of potential failure modes include: Corrosion, torque, fatigue, deformation, cracking, electrical short or open, and hydrogen embrittlement.

6. Describe the potential failure effects

For each failure mode identified the engineer should determine what the ultimate effect will be.

A failure effect is defined as the result of a failure mode on the function of the product/process as perceived by the customer.

Examples of failure effects include: Injury to the user, impaired operation, poor appearance, odours, noise, and degraded performance.

7. Establish a numerical ranking for the severity (S) of the effect

Severity  is the assessment of the seriousness of the failure effect.

A common industry standard scale uses 1 to represent no effect and 10 to indicate very serious effect.

This numerical ranking enables the engineer to prioritize the failures and address the real big issues first.

8. The CLASS column is used to classify any special product characteristics for components, sub-systems, or systems that may require additional process controls.

9. Identify the potential causes/mechanisms of failure

A failure cause is defined as a design weakness that may result in a failure.

The potential causes for each failure mode should be identified and documented.

The causes should be listed in technical terms and not in terms of symptoms.

Examples of potential causes include: Improper torque applied, improper operating conditions, contamination, erroneous algorithms, improper alignment, excessive loading, and excessive voltage.

10. Enter the probability factor

Occurrence (O) is the chance that one of the specific causes/mechanisms will occur.

A numerical weight should be assigned to each cause that indicates how likely that cause is (i.e., probability of the cause causing).

A common industry standard scale uses 1 to represent not likely and 10 to indicate inevitable

11. Identify current controls (design or process)

Current controls (design or process) are the mechanisms that prevent the cause of the failure mode from occurring or which detect the failure before it reaches the customer.

These controls may be supported through tests, mathematical studies, feasibility reviews, and prototype testing.

12. Determine the likelihood of detection (D)

 Detection (D) is an assessment of the likelihood that the current controls will detect the cause of the failure mode or the failure mode itself.

The likelihood of detection is also based on a 1 to 10 scale, with 1 being the certain of detection and 10 being the absolute uncertainty of detection.
13. Review Risk Priority Number (RPN)
The Risk Priority Number (RPN) is defined as the product of the severity (S), occurrence (O), and detection (D) rankings.
That is, RPN  Severity  Occurrence  Detection
or

RPN= (S) x (O) x (D)

 The RPN is used to prioritize items that require additional quality planning or action.

14. Determine recommended action(s)
 Determine recommended action(s) to address potential failures that have a high RPN.
These actions may include specific inspection, testing, de-rating, selection of parts and materials, redesign of the items, monitoring mechanisms, and performing preventive maintenance.
15. Assign responsibility and a target completion date for these actions. This makes responsibility clear-cut and facilitates tracking.
16. Indicate actions taken
After these actions have been taken, re-assess the severity, occurrence and detection and review the revised RPN’s.
17. Update the FMEA as the design or process changes, the assessment changes or new information becomes known.
For Feedback - techactive6@gmail.com

Leave a Comment