Quality Improvement using FMEA : A Short Review

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Quality Improvement Using FMEA : A Short Review

Sourabh Rana

1

_{, Dr. R.M.Belokar}

2

1_{Production Engineering Department PEC University of Technology, Chandigarh} 2_{Production Engineering Department PEC University of Technology. Chandigarh}

---*---Abstract -**

- Failure mode and effect analysis (FMEA) is systematic, proactive method for evaluating the process to identify were and it might be fail to assist the relevant impact of different failures in order to identify the part of processes that are most needed of the change. The FMEA process associated with step wise process starting from potential failure causes ,study existing and complete the working of mechanism , calculate the risk priority number (RPN)of existing and modified. The presented paper deals with the review of industrial case study and implementation of FMEA on them. This work discusses about implementation of Process Failure mode and effect analysis for improvement in welding process through better ment in various sub-processes . We considered various parameters and examined them. The parameters are discussed along with their rankings. Severity, Occurrence and Detection are detected to calculate the Risk Priority Number (RPN). The Risk Priority Number (RPN) can be obtained by multiplying Occurrence with Severity and Detection. RPN gives the idea about the most affecting parameters in the existing welding process. We detected how failure can occur and suggested the preventive action.

Key Words: Severity, Occurrence, Detection and RPN,

DFMEA, PFMEA, SAW Welding and risk evaluation.

1.INTRODUCTION

The purpose of FMEA is to analyze the design characteristics relative to the planned manufacturing process to ensure that the resultant product meets customer needs and expectations. When modes of failure are identified, improvement can be done by reducing the chances for occurrence by taking some correct actions . FMEA provides an organized analysis of failure modes of the system being defined and identifies related causes. It uses probabilities of detection and occurance in addition with a severity criteria to develop a risk priority number (RPN) for ranking corrective action considerations. Used in both

the design and manufacturing processes, they substantially reduce costs by identifying product and process improvements early in the develop process when changes are relatively easy and inexpensive to make. The result obtained found robust ,as the need for post corrective action and problems are reduced completely. This project discuses and implementation of Process Failure mode and effect analysis for improvement in all sub-processes involved till the completion of welding process.

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2.1 Design FMEA (DFMEA)

DFMEA is kind of tool to identify and prevent failure modes of products, that are related to their design, in order to validate the established design parameters for a specific functional performance level, at system, subsystem or component level. It aids in the objective evaluation of design requirements and design alternatives. It provides additional information to aid in the planning of efficient design testing.

In order to eliminate or mitigate the effects, DFMEA plays an important role by selecting the optimal design variant and develop a documentary base to support future designs in order to reduce the risks which is associated with the faulty products that reach to the customers.

2.2 Process FMEA (PFMEA)

The purpose of this variant of FMEA is to determine the potential failure modes of manufacturing/assembly processes at operation, subsystem or system level and to eliminate as early as possible the process faults that could lead to the separation of defective products and avoid using improper methods as part of the processes. PFMEA also provides solutions for the development of future processes and validation programs.

3. Research Methodology

 Step 1: First of all collect the functions of system and make a hierarchical structure. Then divide the system into several subsystems, having number of components.

 Step 2: Now determine the failure modes of each component and its effects. Assign the severity ranking (S) of each failure mode according to the respective effects on the system.

 Step 3: Determine the causes of failure modes and estimate the likelihood of each failure that can occur. Give the rating of ocurrance (O) to each failure mode according to the likelihood of its occurrence.

 Step 4: Make a list of approaches to detect the failures and determine the ability of system to

detect the failures prior to the failures occurring. Hence assign the detection rating (D) of each failure mode.

 Step 5: Calculate the risk priority number (RPN) and prepare the priorities for attention.

 Step 6: Take suitable actions to enrich the performance of system.

 Step 7: Prepare FMEA report in a tabular form.

4.RISK ASSESSMENT FACTORS

Probability of Severity (S): A number from 1 to 10 is selected, depending on the severity of the potential failure mode’s effect

• 1 = no effect

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[image:3.595.36.266.133.332.2]

Table -1:

Severity Ranking Table

Probability of occurrence (O): A number from 1 to 10 is selected, depending on the likelihood of the failure mode’s occurrence

[image:3.595.308.561.158.387.2]

• 1 = very unlikely to occur • 10 = almost certain to occur

Table -2:

Occurrence Ranking Table

Probability of detection (D): A number from 1 to 10 is selected, depending on how unlikely it is that the fault will be detected by the system responsible (design control process, quality testing, etc.)

• 1 = nearly certain detention

[image:3.595.36.291.474.681.2]

• 10 = impossible to detect

Table -3:

Detection Ranking Table

Risk Priority Number (RPN): The failure mode’s risk is calculated by the formula RPN = S x O x D. RPN = Severity x Probability of Occurrence x Probability of Detection. RPN will be a number between 1 (virtually no risk) and 1000 (extreme risk).

[image:3.595.312.550.526.732.2]

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5. Applications

 Used in the design of products and processes (manufacturing line, service procedures, etc.) to anticipate and address potential failure modes early in the process when they are least expensive for correction.

 It contributes to the development of effective maintenance procedures. For instance, MSG-3 analysis for aircraft industry.

 Identifies the failure modes discovered during testing and update the probabilities of occurrence based on the Reliability Growth testing data.

 It is used to evaluate critical plans to modify an existing process.

 Used to investigate the credibility of existing systems/processes.

 Helps in providing a central location for reliability-related information for the process.

 Provides a basic knowledge that helps for the future troubleshooting efforts.

 Acts as a learning tool for new engineers.

 It provides input to other system analyses, for example Reliability Block Diagram (RBD), Fault Tree, etc.

 It can be used to Contribute in the identification of requirements for built-in test equipment (BITE).

 It is also included among Probabilistic Risk Assessment (PRA) techniques (such as in nuclear power and other industries).

 It is performed to satisfy a customer requirement and/or to comply with Safety and Quality requirements, such as:

o Six Sigma

o FDA Good Manufacturing Practices o Process Safety Management Act (PSM

act)

6. Conclusion

In 1950s the attention was paid to the safety to prevent accidents that can be predicted in aerospace industry in advance led to the development of the FMEA methodology. Later, it was introduced as key tool for increasing efficiency and quality in manufacturing processes. In 1970’s automobile company came with FMEA to address the potential problems in the Research and Development (R&D) in the early stage of production and published the

Potential Failure Mode and Effects Analysis Handbook in 1984 to promote FMEA. FMEA methodology is now effectively used in a variety of industries including semiconductor, processing, food service, plastics, software, and healthcare. Several approaches and applications of FMEA have been developed so far. FMEA can be used to optimize the decision making process in new product development in automobile industry .FMEA can be implemented at the design stage once actual failures are observed during test, production and operation.

On the basis of results and analysis stated above we are going to implement FMEA on the sub processes involved in welding processes starting from the sheet handling to welding process.

7. Reference

[1] A. A. Nannikar, D. N. Raut, M. Chanmanwar, S. B. Kamble and D. B. Patil, “FMEA for Manufacturing and Assembly Process”, International Conference on Technology and Business Management, pp. 26-28, March 2012.

[2] Segismundo, Paulo Cauchick Miguel, "Failure mode and effects analysis (FMEA) in the context of risk management in new product development: A case study in an automotive company", International Journal of Quality & Reliability Management, Volume 25 Issue 9, pp.89 – 912, 2008.

[3] Arabian-Hoseynabadi, H. and Oraee, H. and Tavner, P. J. “Failure Modes and Eﬀects Analysis (FMEA) ”, International journal of electrical power and energy systems, Issue 7, pp. 817-824, 2010.

[4] ArunChauhan, Raj Kamal Malik, Gaurav Sharma, MukeshVerma, “Performance Evaluation of Casting Industry by FMEA - A Case Study”, International Journal of Mechanical Engineering Applications Research, Volume 2, Issue 2, pp. 113-121, 2011.

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Industries: A case study”, UdyogPragati, vol.35, Issue 4, pp. 6-14,December 2011.

[7] Ioannis S. Arvanitoyannis and Theodoros H. Varzakas, “Application of ISO 22000 and failure mode and effect analysis [FMEA] for industrial processing of salmon: A case study”, Critical reviews in Food science and Nutrition, Volume 48, pp. 411-429,2008.

Quality Improvement using FMEA : A Short Review