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Mini ReviewDOI Number : 10.36811/ijme.2021.110006Article Views : 68Article Downloads : 47
Risk Priority Number (RPN) assessment in design failure modes and effective analysis for the Automobile Plant using factor analysis
Prabir Namhata1, Amit Rakshit2*, Dr. Sukanta Kumar Naskar3, Dr. Dipankar Bose4 and Dr. Sushovan Chatterjee5
1Assistant Professor, Department of Mechanical Engineering, Mallabhum Institute of Technology, Bishnupur, W.B, prabir.namhata@gmail.com
2Assistant Professor, Department of Mechanical Engineering, KIEM, Mankar, amitrakshit1990@gmail.com
3Associate Professor, Department of Education and Management, NITTTR, Kolkata, sknaskar@nitttrkol.ac.in
4Professor & Head, Department of Mechanical Engineering, NITTTR, Kolkata, dbose@nitttrkol.ac.in
5Associate Professor & HOD, Department of Mechanical Engineering, CGEC, Coochbehar, sushovan.chatterjee@gmail.com
*Corresponding Author: Amit Rakshit, Assistant Professor, Department of Mechanical Engineering, KIEM, Mankar, Email: amitrakshit1990@gmail.com
Article Information
Aritcle Type: Mini Review
Citation: Prabir Namhata, Amit Rakshit, Sukanta Kumar Naskar, et al. 2021. Risk Priority Number (RPN) assessment in design failure modes and effective analysis for the Automobile Plant using factor analysis. I J Mech Eng. 3: 20-24.
Copyright: This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Copyright © 2021; Prabir Namhata
Publication history:
Received date: 19 April, 2021Accepted date: 25 May, 2021
Published date: 27 May, 2021
Abstract
In this article, design of failure mode and effect analysis (DFMEA) is a structured qualities analysis of the system, subsystem and components/functions that highlights impending failures modes of which their cause and effects of a failure on system operation. Few years ago, many industries are forced to use design of failure modes and effect analysis (DFMEA) technique to physically powerful their product design and manufacturing process due to the global competitive market. DFMEA is agreed out systematically by brainstorming. The aim of this paper is to in attendance a new approach for evaluation of RPN and failure modes to augment the utility of the traditional DFMEA technique. At the closing stages, the statistical method of the factor analysis was used to confirm the effectiveness.
Keywords: DFMEA; Failure modes and Factor Analysis; Risk Priority Number (RPN)
Introduction
This method is widely used during the process of design analyze of engineering system from their reliability aspect. It was described as an effective approach to analyzed of each potential mode in the system to examine the failure mode effects on the system. D FMEA also can be applied to various conducting engineering systems safety analysis. The history of DFMEA may be traced flipside to the early years of the 1950s with the development of flight control systems, when U.S Navy’s Bureau of Aeronautics, in order to widen a procedure for reliability control over the detailed design effort to developed a requirement known as Failures Analysis. There are so many factors that must be explored earlier than the implementation of DFMEA. Some of this factor which includes
(i) Examination of each and every conceivable failure mode by the involved professionals.
(ii) Measuring FMEA cost benefits.
(iii). Obtaining engineer’s approval and support.
(iv). Making decisions based on the risk priority number (RPN).
Design Failure Modes and Effect Analysis was an analytical technique old to design phase of a product development. It was a pro active technique worn to identify the weak points of a product design in early stage. Design Failure Modes and Effect Analysis was a specific tool used during product design phase to develop robust and more reliable product. Its aim to recognize and alleviate or eradicate the product failures earlier than releasing the production drawing for the manufacture.
RPN technique was commonly used in the automation industry, based on the risk priority number for an item failure mode based on three factors-
(i). probability of occurrence,
(ii). the severity of the failures effect, and
(iii). probability of failure detection.
The probability of occurrence is the like hood of failure, or relative number of failures, expected during the item’s useful life.
RPN= Occurrence× Severity× Detection
Failure modes with a high RPN are more critical and given a higher priority than ones with a lower RPN.
When the scales used range from 1 to 10, the value of an RPN will be between 1 and 1000. The scales and categories used.
Table 1: Severity (S), Occurrence (O) and Detection (D) guidelines for design DFMEA. |
|||||||
|
Severity (S) |
Occurrence(O) |
Detection(D) |
||||
Rank |
Effect |
Criteria |
Effect |
Criteria |
Effect |
Criteria |
|
10 |
Hazardous |
Hazardous effect |
Almost certain |
Failure almost certain |
Almost impossible e |
No known technique available |
|
9 |
Serious |
Potential hazardous effect |
Very high |
Likely very high number of failures |
Remote |
Only unproven technique available |
|
8 |
Extreme |
Customer very dissatisfied |
High |
Likely high number of failures |
Very slight |
Providing durability test |
|
7 |
Major |
Customer dissatisfied |
Moderate Ely high |
Likely moderate high number of failures |
Slight |
Test on products with prototypes |
|
6 |
Significant |
Customer experiences discomfort |
Medium |
Likely medium number of failures |
Low |
Test on similar system |
|
5 |
Moderate |
Customer experiences some dissatisfaction |
Low |
Likely occasional number of failures |
Medium |
Test on preproduction system |
|
4 |
Minor |
Customer experiences minor nuisance |
Slight |
Likely few failures |
Moderately y high |
Test on early prototypes |
|
3 |
Slight |
Customer slightly annoyed |
Very slight |
Likely very few failures |
High |
Modelling in early stage |
|
2 |
Very slight |
Customer not annoyed |
Remote |
Likely rare number of failures |
Very high |
Proven computer analysis available |
|
1 |
No |
No effect |
Almost never |
History shows no failures |
Almost never |
Proven detection methods available |
|
This paper presents a novel approach for prioritization of RPN S with case study analysis. |
Novel loom for Evaluation of RPN
Case Study-DFMEA for Buffering Machine (Tire Retarding plant).
The proposed methodology for evaluation of RPN was able to deals with the situation when:
(i). The FMEA team has a divergence in the rating scale S, O and D indexes, the RPN means are indistinguishable for more than one failure mode and the three failure indexes S, O and D are equally important.
(ii). The potential failure modes of a Buffering Machine are listed in Table-2. It shows that there is a incongruity in rating scale for S, O and D indexes. We calculated RPNs and their mean for all possible combinations of severity, occurrence and detection ratings. Various combination of S. O and D values are producing an identical value of RPN means 225. First priority should be given to the failure mode which has similar RPN range.
Table 2: Potential failure modes of a Buffering Machine (Tire Retarding plant). |
|||||||||
Produce t Name |
Failure Mode |
Potential Effect of Failure |
Potential cause of Failure |
Severity y (S) |
Occurrence (O) |
Detection n (D) |
RPNs |
RPN |
|
|
|
||||||||
Buffer in Machi ne |
(1) Inspection |
Difficult to use the function |
Low skilled engineer |
8 7 |
5 7 |
4 6 |
160,240,22 4 336,140,21 0 196,294 |
225 |
196 (1) |
(2) Cutting |
Not able to take cutting in tire |
Probably damage Rubber |
6 9 |
3 7 |
8 4 |
144,72,336 168,216, 108,504,25 2 |
225 |
432 (2) |
|
(3) Brushing |
Brushing is not properly |
Not Function ng |
8 2 |
5 10 |
9 3 |
360,120, 720,240,90 30,180,60 |
225 |
690 (5) |
|
(4) Repairing |
Needs frequent repair |
Poor quality materials |
8 4 |
2 8 |
7 8 |
112,128 448,512,56 64,224,256 |
225 |
456 (3) |
|
(5) Build Machine |
Not properly end up to end tire connecting |
Hardware corrupted |
7 5 |
1 9 |
9 6 |
63,42,567 378,45,30 405,270 |
225 |
537 (4) |
|
The planned methodology for the prioritization of the failure modes for the above case study is given as follows: (i). The failure mode with higher RPN is more severe and (ii). The failure mode with smaller RPN range is more severe if the RPNs means are same. |
Statically Psychiatry and Argument
In this paper statistically tools have been used to assess the proposed RPN prioritization methodology. The results shown of each analysis provides sufficient evidence for the usefulness of the proposed method.
Descriptive Statistics
Buffering Machine shows that the means of the RPNs are indistinguishable. Standard deviation of the modes of failure are 65.273, 140.347, 226.779, 173.090 and 208.723. It shows that the most critical failure modes need to be addressed first. Similarly, it is one of the vital roles to be adapted the rank of the failure modes of a Buffering Machine.
Correlation Matrix
From the Table 3 it reveals that the correlation coefficient between a single variable and every other variable in the investigation.
Table 3: Correlation Matrix for S, O and D. |
||||
Coefficient of Correlation |
||||
|
S |
O |
D |
|
Correlation |
S |
1.000 |
-.590 |
.175 |
O |
-.590 |
1.000 |
-.590 |
|
|
D |
.175 |
-.590 |
1.000 |
The Eigen value for the above correlation matrix is 0.2486, 0.8255, and 1.9260. A measure of the multicollinearity among three independent variables is computed from the correlation matrix using the following computation: C =√ (Maximum Eigen value / Minimum Eigen Value)C = √ (1.92596 /0.24857)C = 2.7834The computed value is ≤ 4, thus it provides strong evidence for there is no multicollinearity among these three independents. |
Conclusion
In this paper, we had projected a new methodology for the evaluation of RPNs and the failure modes. Results of statistical analysis are hold up the utility of the proposed methodology. Thus, we conclude that the proposed methodology can be used successfully for the prioritization of failure modes in design failure modes and effect analysis (DFMEA), when:
? The DFMEA team has a disc
? agreement in to the rating scale for S, O and D indexes.
? The RPN means are identical for more than one failure mode.
? Three failure indexes S, O and D are equally important.
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