Basics of Failure Mode Effects Analysis (FMEAs) Implementing in A Manufacturing Organization to Focus on Quailty

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Basics of Failure Mode Effects Analysis (FMEAs) Implementing in A Manufacturing Organization to Focus on Quailty

1Srikanth K M, 2 Sagar S R, 3Kari Ramakrishna, 4 Kotresh U

1, 3,4 Assistant Professor

2Research Assistant,

1, 3,4 Department of Mechanical Engineering, Amruta Institute of Engineering and Management sciences, Bidadi 562109, Banglore (India).

2 Fire & Combustion Research Center, Jain (Deemed-to-be-University), Jakkasandra, Kanakapura 562117

Abstract: The goal of the FMEAs (Failure Mode, Effects and Analysis) process is to determine the consequences that failures may have on the function of a complex system. In manufacturing industries, this process is very important with in international standards. Today, most of the process is performed manually. This can be problematic, since, although the basic process is not difficult, taking into account all behaviors and all the interactions between the behaviors of several components of a system can be very complex, error prone and costly. In this paper, we discuss only the basic concepts implements for design and process FMEAs in manufacturing Sector.

Keywords: FMEAs; DFMEAs; PFMEAs; Severity; Occurance; Detetication; RPN.

  1. HISTORY

    The automotive industry began to use FMEA by the mid- 1970s. The Ford motor company introduced FMEA to the automotive industry for safety and regulatory consideration after the Pinto affair. Ford applied the same approach to processes (PFMEA) to consider potential process induced failures prior to launching production. In 1993 the Automotive Industry Action Group (AIAG) first published an FMEA standard for the automotive industry. The SAE first published related standard J1739 in 1994. This standard is also now in its fourth edition. In 2019 both method descriptions were replaced by the new AIAG / VDA FMEA handbook. It is a harmonization of the former FMEA standards of AIAG, VDA, SAE and other method descriptions.

    Although initially developed by the military, FMEA methodology is now extensively used in a variety of industries including semiconductor processing, food service, plastics, software, and healthcare. Toyota has taken this one step further with its Design Review Based on Failure Mode (DRBFM) approach. The method is now supported by the American Society for Quality which provides detailed guides on applying the method. The standard Failure Modes and Effects Analysis (FMEA) and Failure Modes, Effects and Criticality Analysis (FMECA) procedures identify the product failure mechanisms, but may not model them without specialized software. This limits their applicability to provide a meaningful input to critical procedures such as virtual qualification, root cause analysis, accelerated test programs, and to remaining life assessment. To overcome the

    shortcomings of FMEA and FMECA a Failure Modes, Mechanisms and Effect Analysis (FMMEA) has often been used.

  2. INTRODUCTION

    Failure mode and effects analysis (FMEA) is the process of reviewing many components, assemblies, and subsystems as possible to identify potential failure modes in a system and their causes and effects. For each component, the failure modes and their resulting effects on the rest of the system are recorded in a specific FMEA worksheet. There are numerous variations of such worksheets. An FMEA can be a qualitative analysis, but may be put on a quantitative basis when mathematical failure rate models are combined with a statistical failure mode ratio database. It was one of the first highly structured, systematic techniques for failure analysis. It was developed by reliability engineers in the late 1950s to study problems that might arise from malfunctions of military systems. An FMEA is often the first step of a system reliability study.

    The two most common types of FMEAs are Design – FMEAs (or) DFMEAs and Process-FMEAs (or) PFMEAs.

    1. Design – FMEAs

      The primary objective of a Design-FMEA is to uncover potential failures associated with the product design that could cause:

      • Product malfunctions

      • Shortened product life

      • Safety hazards while using the product

        Design-FMEAs should be used throughout the design process from preliminary design until the product goes into production.

    2. Process – FMEAs

      Process-FMEAs uncover potential failures that can:

      • Impact product quality

      • Reduce process reliability

      • Cause customer dissatisfaction

      • Create safety or environmental hazards

    Ideally, Process-FMEAs should be conducted prior to start-up of a new process, but they can be conducted on existing processes as well.

    Similar principles and steps are followed for both Design and Process FMEAs.

    Figure.1: Types of FMEAs flowchart

    Sometimes FMEA is extended to FMECA (failure mode, effects, and criticality analysis) to indicate that criticality analysis is performed too. FMEA is an inductive reasoning single point of failure analysis and is a core task in reliability engineering, safety engineering and quality engineering.

    Figure.2: FMEA terms Expansions

    A successful FMEA activity helps identify potential failure modes based on experience with similar products and processes or based on common physics of failure logic.It is widely used in development and manufacturing industries in various phases of the product life cycle. Effects analysis refers to studying the consequences of those failures on different system levels.

  3. BASIC TERMs USED IN FMEAs

    The following are some of basic FMEAs terminology.

    1. Failure

      The loss of a function under stated conditions.

    2. Failure Mode

      The specific manner or way by which a failure occurs in terms of failure of the part, component, function, equipment, subsystem, or system under investigation.

      Depending on the type of FMEA performed, failure mode may be described at various levels of detail.

    3. Action Priority

      It makes a statement about the need for additional improvement measures

    4. Failure Cause and Mechanism

      Defects in requirements, design, process, quality control, handling or part application, which are the underlying cause or sequence of causes that initiate a process (mechanism) that leads to a failure mode over a certain time.

      A failure mode may have more causes.

      For Example: "Fatigue or corrosion of a structural beam" or "fretting corrosion in an electrical contact" is a failure mechanism and in itself not a failure mode. The related failure mode is a "full fracture of structural beam" or "an open electrical contact". The initial cause might have been "Improper application of corrosion protection layer" and /or "vibration input from another system".

    5. Failure Effect

      Immediate consequences of a failure on operation, or more generally on the needs for the customer / user that should be fulfilled by the function but now is not, or not fully, fulfilled.

    6. Local Effect

      The failure effect as it applies to the item under analysis

    7. Next Higher Level Effect

      The failure effect as it applies at the next higher indenture level.

    8. End Effect

      The failure effect at the highest indenture level or total system.

    9. Detection

      The means of detection of the failure mode by maintainer, operator or built in detection system, including estimated dormancy period.

      Table.1: Deection score guideline

      Detection

      Criteria: Like hood the Existence of Defect will be detected by process controls before next (or) Subsequent process (or) Before Part (or) Component leaves the manufacturing (or) Assembly Location

      Ranking

      Almost Impossible

      No known control available to detect cause / mechanism of failure.

      10

      Very Remote

      Very remote likelihood current control will detect cause / mechanism of failure.

      9

      Remote

      Remote likelihood current control will detect cause / mechanism of failure.

      8

      Very Low

      Very low likelihood current control will detect cause / mechanism of failure.

      7

      Low

      Low likelihood current control will detect cause / mechanism of failure.

      6

      Moderate

      Moderate likelihood current control will detect cause / mechanism of failure.

      5

      Moderately High

      Moderately likelihood current control will detect cause / mechanism of failure.

      4

      High

      High likelihood current control will detect cause / mechanism of failure.

      3

      Very High

      Very High likelihood current control will detect cause / mechanism of failure.

      2

      Almost Certain

      Current control almost certain to detect cause / mechanism of failure.

      1

      (<100%) reworked. Fit and Finish / squeak & Rattle item does not conform. Defect noticed by average customers.

      Very Minor

      Minor disruption to production line. The product may have to be sorted and a portion (<100%) reworked. Fit and Finish / squeak & Rattle item does not conform. Defect noticed by discriminating customers

      2

      Low

      No Effect

      1

      (<100%) reworked. Fit and Finish / squeak & Rattle item does not conform. Defect noticed by average customers.

      Very Minor

      Minor disruption to production line. The product may have to be sorted and a portion (<100%) reworked. Fit and Finish / squeak & Rattle item does not conform. Defect noticed by discriminating customers

      2

      Low

      No Effect

      1

    10. Probability

      The likelihood of the failure occurring.

      Probability of Failure

      Possible Failure Rates

      Ranking

      Very High: Failure Almost Inevitable

      1 in 2

      10

      1 in 3

      9

      High: Generally associated with process similar to previous processes that have often failed.

      1 in 8

      8

      1 in 20

      7

      Moderate: Generally Associated with processes similar to previous processes which have experienced occasional failures, but not in major proportions.

      1 in 80

      6

      1 in 400

      5

      1 in 2,000

      4

      Low: Isolated failures associated with similar processes

      1 in 15,000

      3

      Very Low: Only Isolated Failures associated with almost Identical Processes.

      1 in 150,000

      2

      Remote: Failure is unlikely. No failures ever associated with almost Identical process.

      1 in 1,500,000

      1

      Probability of Failure

      Possible Failure Rates

      Ranking

      Very High: Failure Almost Inevitable

      1 in 2

      10

      1 in 3

      9

      High: Generally associated with process similar to previous processes that have often failed.

      1 in 8

      8

      1 in 20

      7

      Moderate: Generally Associated with processes similar to previous processes which have experienced occasional failures, but not in major proportions.

      1 in 80

      6

      1 in 400

      5

      1 in 2,000

      4

      Low: Isolated failures associated with similar processes

      1 in 15,000

      3

      Very Low: Only Isolated Failures associated with almost Identical Processes.

      1 in 150,000

      2

      Remote: Failure is unlikely. No failures ever associated with almost Identical process.

      1 in 1,500,000

      1

      Table.2: Probability score guideline

    11. Severity

      The consequences of a failure mode. Severity considers the worst potential consequence of a failure, determined by the degree of injury, property damage, system damage and/or time lost to repair the failure.

      Effect

      Criteria: Severity of Effect

      Ranking

      Hazardous without warning

      May endanger machine (or) operator. Very high severity ranking when a potential failure mode effects safe vehicle operation and/or involves noncompliance with government regulation. Failure will occur without warming.

      10

      Hazardous with warning

      May endanger machine (or) operator. Very high severity ranking when a potential failure mode effects safe vehicle operation and/or involves noncompliance with government regulation. Failure will occur with warming.

      9

      Very High

      Major disruption to production line. 100% of Product may have to be scrapped. Vehicle / Item inoperable. Loss of primary function. Customer very dissatisfied.

      8

      High

      Minor disruption to production line. Product may have to be sorted and a portion (less than 100%) scrapped. Vehicle operable, but a reduced level of performance. Customer dissatisfied.

      7

      Moderate

      Minor disruption to production line. A portion (<100%) of the product may have to be scrapped (no Sorting). Vehicle / Item operable, but some comfort / convenience items inoperable. Customer experience discomfort.

      6

      Low

      Minor disruption to production line.100% of the product may have to be reworked. Vehicle/ item operable, but some comport / convenience items operable at reduced level of performance. Customer experiences some dissatisfaction.

      5

      Very Low

      Minor disruption to production line. The product may have to be sorted and a portion (<100%) reworked. Fit and Finish / squeak & Rattle item does not conform. Defect noticed by most customers.

      4

      Minor

      Minor disruption to production line. The product may have to be sorted and a portion

      3

      Effect

      Criteria: Severity of Effect

      Ranking

      Hazardous without warning

      May endanger machine (or) operator. Very high severity ranking when a potential failure mode effects safe vehicle operation and/or involves noncompliance with government regulation. Failure will occur without warming.

      10

      Hazardous with warning

      May endanger machine (or) operator. Very high severity ranking when a potential failure mode effects safe vehicle operation and/or involves noncompliance with government regulation. Failure will occur with warming.

      9

      Very High

      Major disruption to production line. 100% of Product may have to be scrapped. Vehicle / Item inoperable. Loss of primary function. Customer very dissatisfied.

      8

      High

      Minor disruption to production line. Product may have to be sorted and a portion (less than 100%) scrapped. Vehicle operable, but a reduced level of performance. Customer dissatisfied.

      7

      Moderate

      Minor disruption to production line. A portion (<100%) of the product may have to be scrapped (no Sorting). Vehicle / Item operable, but some comfort / convenience items inoperable. Customer experience discomfort.

      6

      Low

      Minor disruption to production line.100% of the product may have to be reworked. Vehicle/ item operable, but some comport / convenience items operable at reduced level of performance. Customer experiences some dissatisfaction.

      5

      Very Low

      Minor disruption to production line. The product may have to be sorted and a portion (<100%) reworked. Fit and Finish / squeak & Rattle item does not conform. Defect noticed by most customers.

      4

      Minor

      Minor disruption to production line. The product may have to be sorted and a portion

      3

      Table.3: Severity score guideline

    12. Risk Priority Number (RPN)

      Severity (of the event) × Probability (of the event occurring) × Detection (Probability that the event would not be detected before the user was aware of it).

    13. Remarks / Mitigation / Actions

    Additional info, including the proposed mitigation or actions used to lower a risk or justify a risk level or scenario.

  4. FMEAs REPORT AND RISK CHART

    1. FMEAs REPORT

      The purpose of the FMEA is to take actions to eliminate or reduce failures, starting with the highest-priority ones. Failure modes and effects analysis also documents current knowledge and actions about the risks of failures, for use in continuous improvement. FMEA is used during design to prevent failures.

      Table.4: Design and Process FMEAs Report

    2. Risk Chart

    A risk matrix visualizes risks in a diagram. In the diagram, the risks are divided depending on their likelihood and their effects or the extent of damage, so that the worst case scenario can be determined at a glance.

    Significance of Colors in Risk Chart (or) Diagram

    Red: Fire protection, Danger, high risk of injury or death.

    Yellow: Caution statements, Minor risk of injury.

    Green: Safety equipment (or) Information.

    Table.5: Design and Process Risk Chart

  5. ADVANTAGES, DISADVANTAGES AND USES OF FMEAs

    Table.6: Example of FMEAs Report and Risk Chart

    1. Advantages

      • FMEAs can track product failure modes, their causes and effects which provides very valuable knowledge for future product and process design.

      • FMEAs provide the designer with an Indication of the predominant failures that should receive considerable attention while the product is being designed.

      • Actions can be taken to Eliminate or reduce failures in order of quantitatively RPN.

    2. Disadvantages

      • FMEAs is time consuming and tedious to trace failure through FMEA Chart.

      • FMEAs is applied too late and does not affect decision making of design and process.

      • FMEAs depends on subjective analysis and engineers experience that are known by a small group individuals, but fairly unknown and unmanaged at the enterprise level.

      • The relationship between different failure components is disregarded.

    3. Uses

      • Development of system requirements that minimize the likelihood of failures.

      • Development of designs and test systems to ensure that the failures have been eliminated or the risk is reduced to acceptable level.

      • Development and evaluation of diagnostic systems

      • To help with design choices.

  6. CONCULSIONS

    • FMEAs is to take actions to eliminate or reduce failures, starting with the highest-priority ones.

    • FMEAs also documents current knowledge and actions about the risks of failures, for use in continuous improvement.

    • FMEAs is used during design to prevent failures.

    • By taking effectively counter measure we will bring the risk only up to tolerable limit and acceptable limit in all areas of activities but cannot eliminate the hazards and risk completely from the workplace because in manufacturing industry many machinery, substances and activities are in use so there is always have possibility to cause some injury to operators.

    • Thus, there is always some residual risk in process industry. Each of the hazards that remain poses some risk to the workers and the community in the operation of the plant.

    • These risks need to be identified specifically and evaluated. Risks are controlled in several ways and these indicate other source of risk.

    • For any manufacturing industry to be successful it should have to meet not only the production requirements, but also have to sustain the highest safety standards for all concerned.

REFERENCES

  1. Faisal KP, Falah Ummer, Hareesh K C, Munavir Ayaniyat, Nijab K, Nikesh P, Jibi R Application of Fmea Method in a Manufacturing Organization focused on Quality in the journal of International Journal of Engineering and Innovative Technology, ISSN: 2277-3754, Volume 4, Issue 7, pg no 64 -70,January 2015.

  2. Swapnil B. Ambekar A Review: Implementation of Failure Mode and Effect Analysis International Journal of Engineering and Innovative Technology, ISSN: 2277-3754, Volume 2, Issue 8, Feb 2013.

  3. Piyush Kumar pareek, Praveen gowda FMEA implementation in a foundry in Bangalore to improve quality and reliability International journal of mechanical engineering and robotics research, volume1, No.2, July 2012.

  4. JEDEC Publication (May 2005) Potential failure mode and effect analysis JEDEC Solid state technology association.

  5. Failure mode and effect analysis, FMEA doc.

  6. Manufacturing technology committeeFailure mode and effect analysis guide, Risk management working group, May -2008.

  7. Dr.D.R.Prajapati Implementation of failure mode and effect analysis: a literature review International journal of management, IT and Engineering, volume2, issue 7, July 2012.

  8. Dhiraj Kumar Barpete, Vivek Shukla and Dr. G.D Gidwani Job Safety Analysis (JSA) with Risk Assessment in Welding of TLB Dipper by Tack Welding in the journal of International Journal of Science Technology & Engineering, ISSN (online): 2349-784X, Volume 3, Issue 08, February 2017.

  9. https://qualitytrainingportal.com/resources/fmea-resource-center/fmea- types .

  10. https://en.wikipedia.org/wiki/Failure_mode_and_effects_analysis.

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