The Failure Analysis Process: An Overview Debbie Aliya, Aliya Analytical Introduction FAILURE ANALYSIS is a process that is performed in order to determine the causes or factors that have led to an undesired loss of functionality. This Volume primarily addresses failures of components, assemblies, or structures, and its approach is one consistent with the knowledge base of a person trained in materials engineering. The contribution of the materials engineer to the advancement of the scientific foundation of failure analysis has been great in the last few decades. This can be shown by the fact that many people define the causes of failure in a rather binary manner: was the part defective or was it abused? Obviously there are many types of defects, including those that come from a deficient design, poor material, or mistakes in manufacturing. Whether those"defects"exist in a given component that is being subjected to the failure analysis process can often only be determined by someone with a materials background. The reasons for this are related to the fact that many of the"defects"that people are looking for are visible only in a microscope of ome sort. While microscopes may be widely available, the knowledge required to interpret the images is less widely available. The other major type of defects, those related to design issues, may also require the assessment of a materials engineer. This is because many design engineers are not very familiar with the natural variations within a material grade. Evaluation of the adequacy of a material or process specification is often best performed by a materials engineer Thus, materials experts have been in an excellent position to gain experience in the failure analysis process. The advent of more and more powerful and widely available scanning electron microscopes has helped provide a more fact based foundation for opinions that may have been heavily speculative in the past. Some materials engineers have become very experienced in failure analysis. As materials engineers have worked on some very pectacular failures or on failures that have caused great pain and loss, they have been led to ask deeper and broader questions about the causes that lead to failures. In many cases it becomes clear that there is no single cause and no single train of events that lead to a failure. Rather, there are factors that combine at a particular time and place to allow a failure to occur. Sometimes the absence of any single one of the factors may have been enough to prevent the failure. Sometimes, though, it is impossible to determine, at least within the resources allotted for the analysis, whether any single factor was key. If failure analysts are to perform their jobs in a professional manner, they must look beyond the simplistic list of causes of failure that some people still promote. They must keep an open mind and always be willing to get help when beyond their own perience Many beginning practitioners of failure analysis may have their projects defined for them when they are handed a small component to evaluate and, thus, may be able to follow an established procedure for the evaluation This is especially true for someone working within an original equipment manufacturer. If there is someone who has a lot of experience and knowledge of the physical factors that tend to go wrong with the object and an established procedure exists, then a particular analysis may not require extensive pretesting work. However, for the practitioner who works in an independent laboratory or who is looking at a wide variety of components, following a predefined set of instructions for a failure analysis will generally prove to be an inadequate guideline for the investigation. Established"recipe type" procedures are generally inadequate for the more dvanced and broad-minded practitioner as well Although the failure that we are investigating is that of a physical component, assembly, or structure, the failures that lead to such physical failure happen on many levels. In other words, a failure should not be viewed as a single event. It is more useful to view both the failure and the failure analysis as multilevel processes that can be explored in many useful ways. The physical failure-a fracture, an explosion, or component damaged by heat or corrosion-is the most obvious. However, there are always other levels of failures that allow the physical event to happen. For example, even a simple failure whose direct physical cause was an improper hardness value has human factors that allowed the improperly hardened component to be manufactured and used. These human factors are generally very difficult to investigate within a manufacturing organization
The Failure Analysis Process: An Overview Debbie Aliya, Aliya Analytical Introduction FAILURE ANALYSIS is a process that is performed in order to determine the causes or factors that have led to an undesired loss of functionality. This Volume primarily addresses failures of components, assemblies, or structures, and its approach is one consistent with the knowledge base of a person trained in materials engineering. The contribution of the materials engineer to the advancement of the scientific foundation of failure analysis has been great in the last few decades. This can be shown by the fact that many people define the causes of failure in a rather binary manner: was the part defective or was it abused? Obviously, there are many types of defects, including those that come from a deficient design, poor material, or mistakes in manufacturing. Whether those “defects” exist in a given component that is being subjected to the failure analysis process can often only be determined by someone with a materials background. The reasons for this are related to the fact that many of the “defects” that people are looking for are visible only in a microscope of some sort. While microscopes may be widely available, the knowledge required to interpret the images is less widely available. The other major type of defects, those related to design issues, may also require the assessment of a materials engineer. This is because many design engineers are not very familiar with the natural variations within a material grade. Evaluation of the adequacy of a material or process specification is often best performed by a materials engineer. Thus, materials experts have been in an excellent position to gain experience in the failure analysis process. The advent of more and more powerful and widely available scanning electron microscopes has helped provide a more fact based foundation for opinions that may have been heavily speculative in the past. Some materials engineers have become very experienced in failure analysis. As materials engineers have worked on some very spectacular failures or on failures that have caused great pain and loss, they have been led to ask deeper and broader questions about the causes that lead to failures. In many cases it becomes clear that there is no single cause and no single train of events that lead to a failure. Rather, there are factors that combine at a particular time and place to allow a failure to occur. Sometimes the absence of any single one of the factors may have been enough to prevent the failure. Sometimes, though, it is impossible to determine, at least within the resources allotted for the analysis, whether any single factor was key. If failure analysts are to perform their jobs in a professional manner, they must look beyond the simplistic list of causes of failure that some people still promote. They must keep an open mind and always be willing to get help when beyond their own experience. Many beginning practitioners of failure analysis may have their projects defined for them when they are handed a small component to evaluate and, thus, may be able to follow an established procedure for the evaluation. This is especially true for someone working within an original equipment manufacturer. If there is someone who has a lot of experience and knowledge of the physical factors that tend to go wrong with the object and an established procedure exists, then a particular analysis may not require extensive pretesting work. However, for the practitioner who works in an independent laboratory or who is looking at a wide variety of components, following a predefined set of instructions for a failure analysis will generally prove to be an inadequate guideline for the investigation. Established “recipe type” procedures are generally inadequate for the more advanced and broad-minded practitioner as well. Although the failure that we are investigating is that of a physical component, assembly, or structure, the failures that lead to such physical failure happen on many levels. In other words, a failure should not be viewed as a single event. It is more useful to view both the failure and the failure analysis as multilevel processes that can be explored in many useful ways. The physical failure—a fracture, an explosion, or component damaged by heat or corrosion—is the most obvious. However, there are always other levels of failures that allow the physical event to happen. For example, even a simple failure whose direct physical cause was an improper hardness value has human factors that allowed the improperly hardened component to be manufactured and used. These human factors are generally very difficult to investigate within a manufacturing organization
because cultures that allow a particular type of failure to occur will generally not have systems in place that allow simple remedies to be enacted for the deeper level causes. For example, if someone in an organization wants to investigate causes beyond the simple fact of improper hardness, it may be discovered that the incoming (receiving) inspection clerk was not properly trained to take note of reported hardness values Changing a corporate culture to include better training and education is generally very difficult; many corporations are structured so that the people who are responsible for training do not have an open line of communication to those doing the investigation. This only increases the difficulty of implementing change to prevent failures Professionally performed failure analysis is a multilevel process that includes the physical investigation itself and much more. This Section of this Volume is intended to showcase some of the latest thinking on how the different"layers" of the failure analysis process should work together, so that when the analysis or larger investigation is complete, the people involved will have useful knowledge about how to avoid future occurrences of similar problems Failure analysis of the physical object is often defined as a part of a larger investigation whose intent is to prevent recurrences. If we are to take the broadest view of what is required to prevent failures, there is one answer that stands out: education. Education needs to happen at multiple levels and on multiple subjects within an organization, within larger cultural groups, and within humanity in general, if we are to reduce the frequency of failures of physical objects Education, of which job training is a single component, is what allows people at all levels of an organization to make better decisions in time frames stretching from momentary to career long. There are many books now available that have exercises that help the reader to restructure knowledge into a more useful and accessible form(see, for example, titles in the Selected Reference list for this article). There are other books available that help the reader learn to recognize incorrect lines of reasoning; one such book is Ref 1 Specific levels of failure causes have been defined by Failsafe Network as follows I Phy 2. Human 3. Latent 4 Root Clearly, many people involved with failure analysis today call something a root cause when what they are referring to is a simple physical cause. If failure analysis tasks are performed adequately and with luck, at the end the analyst should be able to take the causes found, show that the failure would have happened the way it did, and also show that if something different had happened at some step along the way, the failure would not have occurred or would have occurred differently. The fact that is often revealed at the end of an investigation is that this is not possible. Even a long and involved investigation leaves unknowns. The honest analyst is left to make a statement of the factors involved in allowing conditions that promoted the likelihood of failure. This still a useful task, perhaps more useful than something that pins"blame"on a particular individual or group Understanding the factors that promoted a failure can lead to an understanding of what is required to have a real improvement in durability of products, equipment, or structures. Understanding goes beyond knowledge of facts. Understanding requires integration of facts into the knowledge base of an individual so that the facts may be transformed into knowledge and then into product and/or process improvement By now it should be clear that failure analysis is a task that requires input from people with many areas of expertise. A simple physical failure of a small object may be analyzed by a single individual with basic training in visual evaluation of engineered objects. However, going to the level of using the failure analysis to improve products and processes requires expertise in the various aspects of human relations and education, at the least Failure analysis of a complex or catastrophic failure requires much more people who perform failure analysis as part of their job function need to have an awareness of how their legal obligations are defined People who perform destructive testing on a component that has failed may sometimes be held accountable for the destruction of evidence on a personal level. Company employees need to learn to protect themselves. Investigators who were just doing the job"have been successfully sued by parties that the judicial system determined had a legitimate interest in the outcome of the failure analysis project The days where anyone unquestioningly agrees to destructively test a component that they know or can see has failed " should be over. This places the destructive testing technician or engineer in a difficult position, as it Thefileisdownloadedfromwww.bzfxw.com
because cultures that allow a particular type of failure to occur will generally not have systems in place that allow simple remedies to be enacted for the deeper level causes. For example, if someone in an organization wants to investigate causes beyond the simple fact of improper hardness, it may be discovered that the incoming (receiving) inspection clerk was not properly trained to take note of reported hardness values. Changing a corporate culture to include better training and education is generally very difficult; many corporations are structured so that the people who are responsible for training do not have an open line of communication to those doing the investigation. This only increases the difficulty of implementing change to prevent failures. Professionally performed failure analysis is a multilevel process that includes the physical investigation itself and much more. This Section of this Volume is intended to showcase some of the latest thinking on how the different “layers” of the failure analysis process should work together, so that when the analysis or larger investigation is complete, the people involved will have useful knowledge about how to avoid future occurrences of similar problems. Failure analysis of the physical object is often defined as a part of a larger investigation whose intent is to prevent recurrences. If we are to take the broadest view of what is required to prevent failures, there is one answer that stands out: education. Education needs to happen at multiple levels and on multiple subjects within an organization, within larger cultural groups, and within humanity in general, if we are to reduce the frequency of failures of physical objects. Education, of which job training is a single component, is what allows people at all levels of an organization to make better decisions in time frames stretching from momentary to career long. There are many books now available that have exercises that help the reader to restructure knowledge into a more useful and accessible form (see, for example, titles in the Selected Reference list for this article). There are other books available that help the reader learn to recognize incorrect lines of reasoning; one such book is Ref 1. Specific levels of failure causes have been defined by Failsafe Network as follows: 1. Physical 2. Human 3. Latent 4. Root Clearly, many people involved with failure analysis today call something a root cause when what they are referring to is a simple physical cause. If failure analysis tasks are performed adequately and with luck, at the end the analyst should be able to take the causes found, show that the failure would have happened the way it did, and also show that if something different had happened at some step along the way, the failure would not have occurred or would have occurred differently. The fact that is often revealed at the end of an investigation is that this is not possible. Even a long and involved investigation leaves unknowns. The honest analyst is left to make a statement of the factors involved in allowing conditions that promoted the likelihood of failure. This is still a useful task, perhaps more useful than something that pins “blame” on a particular individual or group. Understanding the factors that promoted a failure can lead to an understanding of what is required to have a real improvement in durability of products, equipment, or structures. Understanding goes beyond knowledge of facts. Understanding requires integration of facts into the knowledge base of an individual so that the facts may be transformed into knowledge and then into product and/or process improvement. By now it should be clear that failure analysis is a task that requires input from people with many areas of expertise. A simple physical failure of a small object may be analyzed by a single individual with basic training in visual evaluation of engineered objects. However, going to the level of using the failure analysis to improve products and processes requires expertise in the various aspects of human relations and education, at the least. Failure analysis of a complex or catastrophic failure requires much more. People who perform failure analysis as part of their job function need to have an awareness of how their legal obligations are defined. People who perform destructive testing on a component that has failed may sometimes be held accountable for the destruction of evidence on a personal level. Company employees need to learn to protect themselves. Investigators who were “just doing the job” have been successfully sued by parties that the judicial system determined had a legitimate interest in the outcome of the failure analysis project. The days where anyone unquestioningly agrees to destructively test a component that they know or can see “has failed” should be over. This places the destructive testing technician or engineer in a difficult position, as it The file is downloaded from www.bzfxw.com
is sometimes difficult to see that something has failed. Corporate cultures that are highly structured and hierarchical can be particularly difficult environments for the failure analysis practitioner, as it may be difficult to even find out if the component has failed. Even if that information is given, relevant background details are often very difficult to obtain, even if the analyst tries. Pressure to finish the analysis in a shorter time frame than is desirable for a quality investigation is commor Those who perform failure analysis work must realize that many people are still unaware of what failure analysts have to offer in terms of allowing clients or fellow employees to replace speculation with facts. The people who request failure analysis work may not be aware that rushing ahead into the destructive portion of an investigation may well destroy much information. The remainder of this article and the following articles in this Section of the Volume are intended to demonstrate proper approaches to failure analysis work. The goal of the proper approach is to allow the most useful and relevant information to be obtained. Readers of the various articles will see many points of view demonstrated. All the valid approaches require planning, defining of objectives, and organization prior to any destructive testing. Simultaneous preservation of evidence is also required. It should now be clear that proper failure analysis cannot be done with input from only a single individual. Even someone only participating in the"straightforward" portions of the investigation of physical failure needs to know how his or her contribution fits into a bigger picture. This is the intent of this Section while the next Section of this Volume is intended to provide an introduction to the vast array of technical tool and information available to the failure analyst The competent failure analyst needs to know more than the failure analysis process and the tools used to support it. The competent failure analyst needs to understand the function of the object being analyzed and to be familiar with the characteristics of the materials and processes used to fabricate it. The failure analyst needs to understand how the product was used and the culture in which it was used. Communication skills are a When you ask a question, do you know for certain what the answer"yes"means? In some cultures, the yes"means"I heard the question"and does not imply that the answer is actually affirmative. The failure analyst must al ways be well versed in multiple disciplines The failure analysis process is something that can be approached in many different ways. Most people who do failure analysis of structural components or larger scale structures and assemblies have probably run into someone who wanted to do a failure analysis without considering a contribution from an experienced materials ngineer. While the analyst may reach a conclusion in this manner, its value should be questioned. A reliable understanding of what happened and why it happened requires the input of a competent materials engineering practitioner. Every"failed"object is made of some material, and some common materials can lose more than 90% of their usual strength if they are not processed properly. Clearly, prior to reaching a conclusion as to the most significant causes of the failure, someone should determine if the correct material d and if it was processed properly. This often requires both an investigation of documentation and a series of physical tests This Volume focuses on the definition of and requirements for a professionally performed failure analysis of a physical object or structure. However, many of the concepts for investigation that are described in this Section have much greater utility than for investigations of physical objects failure. The concepts in learning how to define objectives, negotiate scope of investigation, look at the physical evidence, structure both the investigation and the data that it reveals, and perform general problem solving have broad applicability in other areas of business, manufacturing, and life in general. The examples of how competent materials engineers can use these concepts in a failure analysis or failure investigation are emphasized here Reference cited in this section D. Levy, Tools of Critical Thinking: Metathoughts for Psychology Allyn and Bacon, 1997 The Failure Analysis Process: An Overview Debbie Aliya, Aliya Analytical Principles and Approaches in Failure Analysis Work
is sometimes difficult to see that something has failed. Corporate cultures that are highly structured and hierarchical can be particularly difficult environments for the failure analysis practitioner, as it may be difficult to even find out if the component has failed. Even if that information is given, relevant background details are often very difficult to obtain, even if the analyst tries. Pressure to finish the analysis in a shorter time frame than is desirable for a quality investigation is common. Those who perform failure analysis work must realize that many people are still unaware of what failure analysts have to offer in terms of allowing clients or fellow employees to replace speculation with facts. The people who request failure analysis work may not be aware that rushing ahead into the destructive portion of an investigation may well destroy much information. The remainder of this article and the following articles in this Section of the Volume are intended to demonstrate proper approaches to failure analysis work. The goal of the proper approach is to allow the most useful and relevant information to be obtained. Readers of the various articles will see many points of view demonstrated. All the valid approaches require planning, defining of objectives, and organization prior to any destructive testing. Simultaneous preservation of evidence is also required. It should now be clear that proper failure analysis cannot be done with input from only a single individual. Even someone only participating in the “straightforward” portions of the investigation of physical failure needs to know how his or her contribution fits into a bigger picture. This is the intent of this Section, while the next Section of this Volume is intended to provide an introduction to the vast array of technical tools and information available to the failure analyst. The competent failure analyst needs to know more than the failure analysis process and the tools used to support it. The competent failure analyst needs to understand the function of the object being analyzed and to be familiar with the characteristics of the materials and processes used to fabricate it. The failure analyst needs to understand how the product was used and the culture in which it was used. Communication skills are a must. When you ask a question, do you know for certain what the answer “yes” means? In some cultures, the word “yes” means “I heard the question” and does not imply that the answer is actually affirmative. The failure analyst must always be well versed in multiple disciplines. The failure analysis process is something that can be approached in many different ways. Most people who do failure analysis of structural components or larger scale structures and assemblies have probably run into someone who wanted to do a failure analysis without considering a contribution from an experienced materials engineer. While the analyst may reach a conclusion in this manner, its value should be questioned. A reliable understanding of what happened and why it happened requires the input of a competent materials engineering practitioner. Every “failed” object is made of some material, and some common materials can lose more than 90% of their usual strength if they are not processed properly. Clearly, prior to reaching a conclusion as to the most significant causes of the failure, someone should determine if the correct material was used and if it was processed properly. This often requires both an investigation of documentation and a series of physical tests. This Volume focuses on the definition of and requirements for a professionally performed failure analysis of a physical object or structure. However, many of the concepts for investigation that are described in this Section have much greater utility than for investigations of physical objects failure. The concepts in learning how to define objectives, negotiate scope of investigation, look at the physical evidence, structure both the investigation and the data that it reveals, and perform general problem solving have broad applicability in other areas of business, manufacturing, and life in general. The examples of how competent materials engineers can use these concepts in a failure analysis or failure investigation are emphasized here. Reference cited in this section 1. D. Levy, Tools of Critical Thinking: Metathoughts for Psychology Allyn and Bacon, 1997 The Failure Analysis Process: An Overview Debbie Aliya, Aliya Analytical Principles and Approaches in Failure Analysis Work
a key principle of failure analysis is, first and foremost, to preserve evidence-the analyst must make sure that any necessary information from the subject part or assembly in the as-received condition is captured before anything is done to alter its condition. This principle can be summarized by the following guidelines First, preserve evidence Perform tests in order of less destructive to more destructive in nature Know the limitations of one's personal knowledge Know how to ask for help Do not attempt a failure analysis if the basics of specimen preservation, collection, and selection have not been studied Know when to say no to performing a destructive test Destructive testing obviously includes anything that requires cutting the part. However, even moving fragments of an explosion may cause loss of information that might have been determined from the position of the fragments. Cleaning components can also be problematic; not cleaning can lead to damage by corrosion in the case of many common materials, while cleaning may remove the substances that caused or contributed to the failure or that shed light on the nature of any physical degradation of the components. Sometimes, cleaning of dangerous or toxic substances from the debris of a failure is necessary for the safety of the investigator. The practitioner should also keep in mind that many tests described as"nondestructive are only relatively nondestructive. There are numerous investigations during which the analysts representing different parties have spent long periods of time trying to figure out whether the dye penetrant residue that they detected is a result of the test done after the failure or before the last service period. Again, the phrase nondestructive should be iewed as a relative term It should also be recognized that the problem of failure analysis can be approached in different ways, depending the required depth and scope of analysis. another key principle in failure analysis work is knowing how to lefine the scope of the investigation at the proper time, so that the investigation has the highest chance of allowing the answers to the questions posed to become known. The circumstances of failure problems can be diverse, and even the"simple"principles of failure analysis may be subject to interpretation and examination Even the principle of preserving evidence may involve judgments, as noted in the preceding paragraph. Even the experienced analyst can make mistakes. For example, consider a situation in which an analyst received a bearing from a regular client. The bearing had worn out prematurely in a durability test. The analyst was requested to photograph the wear marks and check the hardness and quality of heat treating of the races and balls. The bearing was covered with a black greasy substance. When analyzing wear failures, it is often the lubricant properties and the wear particles that offer the most information about the wear process. The analyst informed the client of this, and the client made the decision to sacrifice the"dirty grease in the interest of completing the investigation in a shorter time. The client just wanted to know if the part met the specification and whether there was evidence of gross misalignment or dimensional problems. After the investigation was finished, and the grease had been dissolved in solvent and discarded, another individual at that company requested detailed information on the actual wear mechanism. At that point, it was too late to analyze the lubricant. If either the client or the analyst had taken more time, a sample of this material could have been set aside and preserved Another key principle of failure analysis is that for all but the simplest routine investigations, there may be multiple, legitimate approaches. Selecting the most appropriate of these approaches to problem solving in failure investigations. some of which are described later in this article and elsewhere in this volume is an important skill. The classical approach is to follow a list of steps, which generally include planning the investigation, performing background research, and writing the report, as well as the actual physical tests and evaluations to which the component in question is subjected. Even though a recipe of procedures has many merits, especially for the beginners in the practice of failure analysis, performing a series of tests does not always produce results that allow the analyst to reach a clear conclusion with ease. Also, if failure analysis is presented exclusively as a series of steps or recipes, the repetitive steps may be conducive to carelessness. If the process of failure analysis is viewed as just a routine series of procedures, the practitioner may not notice the presence of new or different features. This is not to say that structured approaches are bad. However, the importance of paying attention to detail and learning to ask oneself whether each detail is consistent with the other previously noted details can hardly be overemphasized to the beginning failure analyst. Failure analysis is Thefileisdownloadedfromwww.bzfxw.com
A key principle of failure analysis is, first and foremost, to preserve evidence—the analyst must make sure that any necessary information from the subject part or assembly in the as-received condition is captured before anything is done to alter its condition. This principle can be summarized by the following guidelines: · First, preserve evidence. · Perform tests in order of less destructive to more destructive in nature. · Know the limitations of one's personal knowledge. · Know how to ask for help. · Do not attempt a failure analysis if the basics of specimen preservation, collection, and selection have not been studied. · Know when to say no to performing a destructive test. Destructive testing obviously includes anything that requires cutting the part. However, even moving fragments of an explosion may cause loss of information that might have been determined from the position of the fragments. Cleaning components can also be problematic; not cleaning can lead to damage by corrosion in the case of many common materials, while cleaning may remove the substances that caused or contributed to the failure or that shed light on the nature of any physical degradation of the components. Sometimes, cleaning of dangerous or toxic substances from the debris of a failure is necessary for the safety of the investigator. The practitioner should also keep in mind that many tests described as “nondestructive” are only relatively nondestructive. There are numerous investigations during which the analysts representing different parties have spent long periods of time trying to figure out whether the dye penetrant residue that they detected is a result of the test done after the failure or before the last service period. Again, the phrase nondestructive should be viewed as a relative term. It should also be recognized that the problem of failure analysis can be approached in different ways, depending on the required depth and scope of analysis. Another key principle in failure analysis work is knowing how to define the scope of the investigation at the proper time, so that the investigation has the highest chance of allowing the answers to the questions posed to become known. The circumstances of failure problems can be diverse, and even the “simple” principles of failure analysis may be subject to interpretation and examination. Even the principle of preserving evidence may involve judgments, as noted in the preceding paragraph. Even the experienced analyst can make mistakes. For example, consider a situation in which an analyst received a bearing from a regular client. The bearing had worn out prematurely in a durability test. The analyst was requested to photograph the wear marks and check the hardness and quality of heat treating of the races and balls. The bearing was covered with a black greasy substance. When analyzing wear failures, it is often the lubricant properties and the wear particles that offer the most information about the wear process. The analyst informed the client of this, and the client made the decision to sacrifice the “dirty grease” in the interest of completing the investigation in a shorter time. The client just wanted to know if the part met the specification, and whether there was evidence of gross misalignment or dimensional problems. After the investigation was finished, and the grease had been dissolved in solvent and discarded, another individual at that company requested detailed information on the actual wear mechanism. At that point, it was too late to analyze the lubricant. If either the client or the analyst had taken more time, a sample of this material could have been set aside and preserved. Another key principle of failure analysis is that for all but the simplest routine investigations, there may be multiple, legitimate approaches. Selecting the most appropriate of these approaches to problem solving in failure investigations, some of which are described later in this article and elsewhere in this Volume, is an important skill. The classical approach is to follow a list of steps, which generally include planning the investigation, performing background research, and writing the report, as well as the actual physical tests and evaluations to which the component in question is subjected. Even though a recipe of procedures has many merits, especially for the beginners in the practice of failure analysis, performing a series of tests does not always produce results that allow the analyst to reach a clear conclusion with ease. Also, if failure analysis is presented exclusively as a series of steps or recipes, the repetitive steps may be conducive to carelessness. If the process of failure analysis is viewed as just a routine series of procedures, the practitioner may not notice the presence of new or different features. This is not to say that structured approaches are bad. However, the importance of paying attention to detail and learning to ask oneself whether each detail is consistent with the other previously noted details can hardly be overemphasized to the beginning failure analyst. Failure analysis is The file is downloaded from www.bzfxw.com
an iterative and creative process, much like the design process, but with reversed roles of synthesis and analysis. See the article"Materials Selection for Failure Prevention "in this volume Knowing which approach to use is at least as important as knowing how to use it. This article describes some of he factors and conditions that might be considered when approaching a failure analysis problem. In any case, whichever approach is taken, it is always important to cultivate an open mind and to the temptation to reach a conclusion about the cause(s)of the failure before performing the analysis and evaluation. The science of critical thinking has a principle called the confirmation bias, which refers to the tendency to look only for what one expects to find: that is, "Ye shall find only what ye shall seek"(Ref 1). Humans have a general tendency to see what they expect to see or to perceive things according to preconceived expectations. As Mark Twain wrote, "To the man who wants to use a hammer badly, a lot of things look like nails that need hammering. If observation is limited to an expected outcome, helpful data may be overlooked. For example, one of the biggest mistakes that people make in failure analysis work is defining the investigation in binary terms of"was there a manufacturing defect or was the object abused? The professional analyst should not be confined to this small set of possible causes for the failure, because it may be difficult to become aware of the situation of not finding what he or she did not set out to find It is also important to appreciate the value of intuition and instinct. While the importance of observation and analysis can hardly be overemphasized, sometimes intuition can provide insights and a better appreciation of the big picture. For years, the great 19th-century Indian mathematician Ramanujan would, immediately upon awakening, write down theorems that had come to him in his dreams. many of these theorems remain unproven et useful to mathematicians and physicists today(Ref 2). Another example is the discovery of the structure of the benzene ring by F.A. Kekule. Many high-school science books report that during the period of time when he was trying to figure out how the carbon and hydrogen atoms were arranged within the molecule, he had a vision in a dream of intertwined serpents, each biting its own tail. Obviously, he and others went on to use more cientific methods to demonstrate the correctness of his theory. Likewise while any failure investigation must intuitive function in engineering and scientific work in genery orically, too little credit has been given to the stand or fall on the merits of the analytical work done, hi References cited in this section 1. D. Levy, Tools of Critical Thinking: Metathoughts for Psychology Allyn and Bacon, 1997 2. M. Kaku, Hyperspace, Oxford University Press, 1994 The Failure Analysis Process: An Overview Debbie Aliya, Aliya Analytica The Objectives of Failure Analysis The objective or purpose of a failure analysis project is often described to be preventing a recurrence of the failure. However, there are many different types of failure analysis projects. Where an injury lawsuit is involved, for example, it may be important to assign responsibility for an undesired event. There are other cases when there may never be a chance for a recurrence. For example, if the item that fails is unique, there may never be a repeat incident Another case in which the objective of the investigation may not be the prevention of recurrences is one involving a very minor failure of a low-value component. If there is no other damage, it may be difficult to justify a prevention-oriented project. It may be more economical to live with a certain level of failure than to devote resources to prevention. The work is still worthwhile, because if certain economic situations change, there is background information available to support a broader investigation, in a more efficient manner, at a later time. Also, the understanding gained may lead to an improved product that may be appropriate for particular market niche, for example, long- life light bulbs
an iterative and creative process, much like the design process, but with reversed roles of synthesis and analysis. See the article “Materials Selection for Failure Prevention” in this Volume Knowing which approach to use is at least as important as knowing how to use it. This article describes some of the factors and conditions that might be considered when approaching a failure analysis problem. In any case, whichever approach is taken, it is always important to cultivate an open mind and to minimize the temptation to reach a conclusion about the cause(s) of the failure before performing the analysis and evaluation. The science of critical thinking has a principle called the confirmation bias, which refers to the tendency to look only for what one expects to find: that is, “Ye shall find only what ye shall seek” (Ref 1). Humans have a general tendency to see what they expect to see or to perceive things according to preconceived expectations. As Mark Twain wrote, “To the man who wants to use a hammer badly, a lot of things look like nails that need hammering.” If observation is limited to an expected outcome, helpful data may be overlooked. For example, one of the biggest mistakes that people make in failure analysis work is defining the investigation in binary terms of “was there a manufacturing defect or was the object abused?” The professional analyst should not be confined to this small set of possible causes for the failure, because it may be difficult to become aware of the situation of not finding what he or she did not set out to find. It is also important to appreciate the value of intuition and instinct. While the importance of observation and analysis can hardly be overemphasized, sometimes intuition can provide insights and a better appreciation of the “big picture.” For years, the great 19th-century Indian mathematician Ramanujan would, immediately upon awakening, write down theorems that had come to him in his dreams. Many of these theorems remain unproven yet useful to mathematicians and physicists today (Ref 2). Another example is the discovery of the structure of the benzene ring by F.A. Kekulé. Many high-school science books report that during the period of time when he was trying to figure out how the carbon and hydrogen atoms were arranged within the molecule, he had a vision in a dream of intertwined serpents, each biting its own tail. Obviously, he and others went on to use more scientific methods to demonstrate the correctness of his theory. Likewise, while any failure investigation must stand or fall on the merits of the analytical work done, historically, too little credit has been given to the intuitive function in engineering and scientific work in general. References cited in this section 1. D. Levy, Tools of Critical Thinking: Metathoughts for Psychology Allyn and Bacon, 1997 2. M. Kaku, Hyperspace, Oxford University Press, 1994 The Failure Analysis Process: An Overview Debbie Aliya, Aliya Analytical The Objectives of Failure Analysis The objective or purpose of a failure analysis project is often described to be preventing a recurrence of the failure. However, there are many different types of failure analysis projects. Where an injury lawsuit is involved, for example, it may be important to assign responsibility for an undesired event. There are other cases when there may never be a chance for a recurrence. For example, if the item that fails is unique, there may never be a repeat incident. Another case in which the objective of the investigation may not be the prevention of recurrences is one involving a very minor failure of a low-value component. If there is no other damage, it may be difficult to justify a prevention-oriented project. It may be more economical to live with a certain level of failure than to devote resources to prevention. The work is still worthwhile, because if certain economic situations change, there is background information available to support a broader investigation, in a more efficient manner, at a later time. Also, the understanding gained may lead to an improved product that may be appropriate for a particular market niche, for example, long-life light bulbs