Introduction to Failure Modes and Effective Analysis

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Information about Introduction to Failure Modes and Effective Analysis

Published on December 15, 2016

Author: ChetanKumar217



2. FMEA  Also called: potential failure modes and effects analysis; failure modes, effects and criticality analysis (FMECA)  Failure modes and effects analysis (FMEA) is a step-by-step approach for identifying all possible failures in a design, a manufacturing or assembly process, or a product or service  “Failure Modes” are any errors or defects, especially ones that affect the customer, and can be potential or actual  “Effects analysis” refers to studying the consequences of those failures.

3. When to use FMEA  When a process, product or service is being designed or redesigned, after quality function deployment  When an existing process, product or service is being applied in a new way.  Before developing control plans for a new or modified process  When improvement goals are planned for an existing process, product or service  When analysing failures of an existing process, product or service  Periodically throughout the life of the process, product or serviceAnalyze Improve Control

4. FMEA Process  The cross functional team of people with diverse knowledge about the process, product or service is assembled  They identify the scope of FMEA, its boundaries, its details  Flowcharts are used to identify its scope  Identifying information is filled at the top of the FMEA form FMEA Form Format

5.  Function of the product, design or service is written  For each function, the ways in which failure could happen is identified. These are the Potential Failure Modes  For each Failure Mode, all the consequences of that system, process, product or service, are identified. These are the Potential Effects of Failure

6.  Determination of how serious each effect is, is done. This is the Severity rating(S)  Usually rated on a scale from 1 to 10  1: Insignificant, 10: Catastrophic  If the failure mode has more than 1 effect, write on the FMEA table only the highest severity rating for that failure mode

7.  For each failure mode, determination of all the potential root causes is done by using the cause analysis tools  For each cause, determination of the Occurrence rating is done  Done on a scale of 1 to 10  1: extremely unlikely, 10: inevitable  For each cause, the process control is identified. These are the tests, which are performed to keep failure from reaching the customers

8.  For each control, the Detection Rating(D) is done. This estimates how well the controls can detect either the cause or its failure mode after they have happened  Done on a scale of 1 to 10  1: absolutely certain to detect the problem  10: absolutely certain not to detect the problem

9.  Critical characteristics which is optional for most of the industries  Risk Priority Number(RPN) which is the multiplication of Severity, Occurrence and Detection Rating is calculated  These numbers provide guidance for ranking Potential Failures in the order the should be addressed  The recommended actions are the identified. These actions may be the design or process changes to lower the severity and occurrence  As actions are completed, results and the data is noted on the FMEA form along with the S, O and D ratings and the new RPN’s RPN = Severity * Occurrence * Detection

10. FMEA Procedure Flowchart

11. Benefits of FMEA  Improve product/process reliability and quality  Increase customer satisfaction  Early identification and elimination of potential product/process failure modes  Helps prioritize product/process deficiencies  Capture engineering/organization knowledge  Documents risk and actions taken to reduce risk  Provides focus for improved testing and development  Minimizes late changes in the design and its associated costs

12. Example  Two fleece fabrics, one single jersey and one rib fabric are used for study because of their widely usage in knitting industry

13.  Traces of platin, fly, broken needle, lycra eccentric, number of hole, transverse band, and lycra cut are determined as the most critical errors  Calculating of RPN has indicated the necessity of applying corrective and preventive actions for each type of error  Most critical errors have been occurred by knitting machines  Although some errors are due to workers, the main reason of errors are depend on making the necessary settings of equipment incompletely and hasty  RPN should be push down to have zero defect by reducing


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