Failure Effect Mode Analysis By Rajeev Kishore Uros

Great question; a confusion in estimation How a raw egg bounce?

Tacoma Bridge Collapse Gondola FMEA

Introduction to FMEA To introduce new products or manufacturing processes successfully in a cost-effective manner, resources should be allocated up-front to prevent problems. Fixing the problem after a product is manufactured is more expensive than it is to prevent them.

Benefits of FMEA Reduce the number of engineering changes Reduce product development time Lower start-up cost, and reduces warranty Greater customer satisfaction Increased cooperation and teamwork between various functions A well-documented project history and information database

Do you know? “Failure Modes...” is a misnomer — some sources now call FMEA by another name: “Fault Hazard Analysis.”

Reliability Failures are expensive System flakiness is a major source of user frustration - 25% in survey have seen peers kicking their computers - 2% claim to have hit the person next to them in their frustration

Failures are not very well understood No Publicly available data on failures on real systems WHY?

Different types of FMEA Design (DFMEA): technique used primarily by a Design Responsible Engineer/Team as a means to assure potential failure modes, causes and effects have been addressed for design related characteristics Process (PFMEA): technique used primarily by a Manufacturing Engineer/Team as a means to assure potential failure modes, causes and effects have been addressed for process related characteristics

The Pre-work Process or Prepared By ____________ Product Name _____ Page ________of ________ Person Responsible __________________ FMEA Date (Orig.) _______ Revised _______

Guide to do FMEA STEP 1 STEP 2 STEP 3 STEP 4 STEP 5 STEP 6 STEP 7 Scope Project STEP 2 Brainstorm all potential failures STEP 3 Identify potential effects of failures STEP 4 Determine severity rankings STEP 5 Identify causes of failures STEP 6 Determine occurrence rankings STEP 7 Define current control methods STEP 8 Determine detection rankings STEP 9 Calculate Risk Priority Numbers STEP 10 Prioritize corrective actions

FMEA Worksheet Function Failure mode Failure effect S Failure Cause O Current Control D RPN Rec. Actions 1. 2.

Terms and Definitions Fault Failure Function/Process Examples – 1. Pencil Sharpener 2. Oil changing process Fault: Inability to function in a desired manner, or operation in an undesired manner, regardless of cause. Failure: A fault owing to breakage, wear out, compromised structural integrity, etc. FMEA does not limit itself strictly to failures, but includes faults. All failures are faults; not all faults are failures. Faults can be caused by actions that are not strictly failures.

Def. Cont… Failure Mode The way failure occurs Can cause a failure mode in another item Identify and list possible failure modes Examples – 1. Frequently breaking the graphite 2. Wrong type of oil or No oil added Brainstorm all potential failure modes utilize process flow chart – break down each step Use knowledge of previous and existing parts/processes Review all quality information like complaints, scrap, rework, turn backs, reviews, etc. Talk to internal and external customer.

Def. Cont… Failure Effect Immediate consequence of a failure Effects can range from very small to major disasters. Examples – Improper writing Engine wear or Engine Failure

Def. Cont… Severity (SEV) Worst consequence of a failure How is it determined? Standard scale from 1 (no danger) to 10 (very severe) Prioritize the failures modes and their effects You may need to involve your customer in allocating this number

Def. Cont… Failure Cause Design weakness - How the failure could occur? Listed in technical terms and are documented Examples – 1. Improper mixture of Graphite and Clay 2. Misread oil chart or Hurrying How the failure could occur, described in terms of something that can be corrected or controlled There could be more than one cause for each failure Experiments have to be conducted to determine causes – use technical problem solving

Def. Cont… Occurrence (O) Probability of the cause occurring Look for similar products or processes Probability number scale from 1 (not likely) to 10 (inevitable) Detailed development section of FMEA Process

Def. Cont… Current Controls Current controls that prevent the failure cause (before causing effects) Examples – 1. improve quality of graphite 2. No control or engine light Systematic device/methods in place to prevent or detect failure modes or causes (before causing effecs) Control consists of inspection, audits, training, etc.

Def. Cont… Detection (D) Assessment of the likelihood that the current controls will detect failure cause or failure, before it reaches the customer. Different techniques are used by an engineer Identify the detection number ‘D’, ranging from 1 (easily detectable) to 10 (cannot detect)

Def. Cont… Risk Priority No (RPN) RPN = S * O * D Risk that has greatest concern can be identified Failures are prioritized according to: - Severity - Occurrence - Detection Requires additional planning or action

Pareto Diagram

Recommended Actions and Results Address potential failures that have a high RPN Are any further actions required? Assign new value for S, O and D, and calculate new RPN value Update the FMEA as the design or process changes After these actions have been taken, re-assess the severity, probability and detection and review the revised RPN’s. Update the FMEA as the design or process changes, the assessment changes or new information becomes known, for e.g. customer feedback or customer reviews on a product or service. FMEA must be a live document. Review regularly. Reassess rankings whenever changes made to product and/or process. Add any new defects or potential problems when found.

Development Team Crucial step in FMEA FMEA is a team function - Formulate cross functional team - Understand customer requirements – both internal and external inputs - All team members walk and observe the process - Make notes or observations

Link with continuous improvement FMEA Continuous Improvement Programs Component Proving Process Mistake Proofing Techniques

FMEA Timing FMEA should be updated whenever: - At the conceptual stage - Changes are made in the design - New regulations are instituted - Customer feedback indicates a problem

Uses of FMEA Development of methods to design Test systems to ensure that the failures are eliminated Tracking and managing potential risks Ensuring that failure will not injure customer or impact a system Evaluation of customer reviews on the problems indicated

TQM Principles Continuous Improvement Process Continued building and prevention of failure on the process Employee Involvement and Empowerment Employees can feel empowered and involved if they correct an error in a process or part. Leadership There needs to be a team leader for every group, which is assigned to one part of the process.

TQM Principles Performance Measurement RPN, lower the better Supplier Partnership If one supplier has bad parts, it directly affects your products, by creating failure in your company. End Customer Satisfaction Reliability meets customer requirements 30

Limitations FMEA is limited by the team experience FMEA may only identify and avoid major failure modes Multiplication of rankings may result in rank reversals

FMEA Conclusion Purpose of FMEA, is the process of identifying potential failure modes and their associated causes, assigning severity, Occurrence, and Detection ratings, and calculating RPN RPNs should be used for continuous improvement activities

Resources http://www.pehwhk.com/Flyers/FAILURE%20MODE%20EFFECT%20ANALYSIS%20_FMEA_.pdf http://www.fmeainfocentre.com/handbooks/fmeamanual.pdf http://www.fmeainfocentre.com/handbooks/umich.pdf. http://www.aluminiumville.co.uk/images/lightbox/aluminium_process.jpg www.nitrd.gov/subcommittee/hec/workshop/20060816/Data/HECIWG-FSIO-2006-Data-Failure-Schroeder.pdf http://www.npd-solutions.com/fmea.html http://www.sigmazone.com/gondola_lift_fmea.htm http://www.suppliermanager-online.com/training/corporation/fmea_training.pdf