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Reliability Engineering: Trends, Strategies and Best Practices Reliability Engineering: Trends, Strategies and Best Practices WHITE PAPER September 2007 Predictive HCL’s Predictive Engineering encompasses the complete product life-cycle process, from concept to design to prototyping/testing, all the way to manufacturing. This helps in making decisions early Engineering in the design process, perfecting the product – thereby cutting down cycle time and costs, and Think. Design. Perfect! meeting set reliability and quality standards. Reliability Engineering: Trends, Strategies and Best Practices | September 2007 TABLE OF CONTENTS Abstract 3 Importance of reliability engineering in product industry 3 Current trends in reliability engineering 4 Reliability planning – an important task 5 Strength of reliability analysis 6 Is your reliability test plan optimized? 6 Challenges to overcome 7 Outsourcing of a reliability task 7 About HCL 10 © 2007, HCL Technologies. Reproduction Prohibited. This document is protected under Copyright by the Author, all rights reserved. Reliability Engineering: Trends, Strategies and Best Practices | September 2007 Abstract In reliability engineering, product industries now follow a conscious and planned approach to effectively address multiple issues related to product certification, failure returns, customer satisfaction, market competition and product lifecycle cost. Today, reliability professionals face new challenges posed by advanced and complex technology. Expertise and experience are necessary to provide an optimized solution meeting time and cost constraints associated with analysis and testing. In the changed scenario, the reliability approach has also become more objective and result oriented. This is well supported by analysis software. This paper discusses all associated issues including outsourcing of reliability tasks to a professional service provider as an alternate cost-effective option. Importance of reliability engineering in product industry The degree of importance given to the reliability of products varies depending on their criticality. For instance, failure of a critical unit in a flight control system may cause loss of human life and property, whereas an unreliable ignition system in a car may lead to customer dissatisfaction. Reliability has a direct or indirect impact on some aspects like profitability due to poor market feedback and reduced sales. The respective product manufacturers have a common concern about reliability but for different reasons. Regulatory requirements warrant compliance to applicable Reliability and Safety (R&S) standards. In the aerospace and life sciences domain, inadequate product reliability may lead to loss of safety critical functions of an aircraft or a life-supporting system, respectively. Reliability engineering practice during the product development program is mandatory. Manufacturers strictly prioritize associated tasks during the development program in accordance with R&S requirements. © 2007, HCL Technologies. Reproduction Prohibited. This document is protected under Copyright by the Author, all rights reserved. Reliability Engineering: Trends, Strategies and Best Practices | September 2007 On the contrary, reliability practice in automotive, semiconductor and hi-tech domains is driven by product functional requirements, business profitability, market competition and customer satisfaction. The need for products to conform to higher performance limits has increased the complexity and poses a challenge to reliability practitioners. One recent unfortunate example is of space shuttles Challenger and Columbia with the state-of-the-art technology that met the required performance limits. The fatal accidents of these space shuttles after 9 and 27 respective successful missions raise a serious question on R&S of these products. Current trends in reliability engineering Does the accomplishment of reliability tasks assure definite improvement in product reliability? No; in case the selected tasks are not effective and efficient, the effort may not yield the expected result. We need to learn from our past experience and have a focused approach in line with current trends. The world reliability community believes in sharing best practice experience so as to provide reliable products to all customers. The following are a brief on the current trends: Is your reliability assurance dependent only on numeric values? The reliability prediction of a medical device may show compliance to 99% target reliability. However, current reliability practice additionally recommends applicable qualitative failure analyses such as hazard analysis and Failure Modes Effect Analysis (FMEA) to analyze all associated failure conditions and modes. The objective is to improve reliability addressing design weaknesses. Reliability prediction, allocation and FTA are the common tools used to address specific quantitative requirements. The current reliability practice does emphasize qualitative analysis without ignoring the importance of quantitative analysis. Are you tracking preferred practice and regulatory changes? In the aerospace domain, FAR/ JAR 25.1309 and ARP 4761 have brought clarity and minimized subjectiveness in the approach. Risk analysis of medical devices is one of the most important tasks for conformance to regulatory requirements. Design control and validation requirements emphasize need for risk analysis vide 21 CFR section 820.30, and relevant guidelines are provided in ISO 14971. The structured approach with design for reliability (DFR) is now being practiced during product development in other non-aerospace domains. Hazard analysis, FMEA, Fault Tree Analysis (FTA) and reliability prediction are invariably part of the DFR activity. Looking for an alternate reliability life test? The current product lifecycle is short, and hence conventional long-duration reliability tests have been phased out. Short-duration test approaches such as Accelerated Life Test (ALT) and Highly Accelerated Life Test (HALT) are now preferred options for reliability validation. © 2007, HCL Technologies. Reproduction Prohibited. This document is protected under Copyright by the Author, all rights reserved. Reliability Engineering: Trends, Strategies and Best Practices | September 2007 Can analysis be a substitute for a reliability test? This can be explained by drawing an analogy, as follows. A sales representative may provide details on technological features of a mobile handset or a car, but customers always prefer to have a performance demonstration test in spite of their prior knowledge and confidence on the product technology. Similarly, a reliability validation test cannot be replaced by an analytical assessment; however, it can certainly minimize the dependence on testing. Late availability of information on product reliability with a requirement of a sizeable budget is the common concern against reliability tests. A rational approach with analysis and/ or testing may be judiciously planned. A reliability test on a product, which is not safety critical, may be waived if supportive design study, component reliability data, engineering stress analysis, similarity analysis and product design qualification test data are available. How to minimize the uncertainty of a quantitative prediction? A great deal of effort has been put into the preparation of a common failure database that significantly supports the reliability prediction task. NPRD95, MIL-HDBK-217FN2, FMD97 and NPRD3 are different failure databases in the public domain. Manufacturers need to create and maintain failure databases of their own products. Accuracy of analysis will be better with the use of product-specific failure data. Product repair and defect investigation data need to be preserved and maintained for creating a product-specific failure database over a period of time. Do you accept failure as a random occurrence? Experience has taught manufacturers not to treat failures as random occurrences. Now they try to understand failure mechanism with a physics- of-failure approach which consequently may contribute in reduction of constant failure rate and extension of useful life. Advanced technology for failure investigation is available and helps identify the root cause and provides options to fix it. Reliability planning – an important task Reliability analysis findings are normally reviewed during an important phase of product design and development. It becomes an uphill task to complete the analysis in a short time unless continuous effort is made throughout the development program as per the schedule detailed in the reliability plan. Inadequate planning may result in an incoherent approach. This may lead to either omission of or delay in carrying out important analyses in the development program, thus leaving limited options for design improvement. DFR underlines the importance of a reliability plan. Do not use a common template for a reliability plan Every product design and its development program are unique. Meticulous planning is required to map the reliability tasks to the identified program objectives and constraints. © 2007, HCL Technologies. Reproduction Prohibited. This document is protected under Copyright by the Author, all rights reserved. Reliability Engineering: Trends, Strategies and Best Practices | September 2007 What should a reliability plan essentially contain? A reliability plan is a framework for achieving program objectives for product reliability which include identification and scheduling of reliability tasks traceable to requirements, approach
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