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There are different types of FMEAs for different business applications. The two most commonly used ones are the Design FMEA and the Process FMEA.

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Quick reference

Types of FMEAs

There are multiple types of FMEAs that are focused on particular applications or uses of the analysis.  While each has a different focus, they all have similarities in structure, evaluation and scoring.  The two most commonly used FMEAs are the Design FMEA and the Process FMEA.

When to use

The basic approach to FMEA is consistent across all the types of FMEAs.  The specific scoring criteria are different depending upon the type of FMEA.  While it is always appropriate in a design or development activity to use FMEAs, the type will change depending upon the phase or the project and subject of analysis.

Instructions

The table below shows the different types of FMEAs and their purpose.  The most common types are the Design FMEA and Process FMEA with the Concept FMEA and Application FMEA being special cases of the Design FMEA, and the Machinery FMEA being a special case of the Process FMEA.

Similarities

There are many similarities among all the FMEAs. Since the two primary types are Design FMEA and Process FMEA, we will focus on these types. 

  • All of the FMEAs rely upon identifying failure modes, effects, and causes.
  • Failure modes are evaluated for severity of the effect, probability of occurrence, and detection capability of the product, process, or operator.
  • FMEAs are used to identify and prioritize critical characteristics so that they can be emphasized in the design and production analysis.
  • Severity scores are normally the same for a particular failure mode regardless of the type of FMEA being used.
  • A Risk Priority Number (RPN) is calculated for each failure mode, occurrence enabler, and detection approach which is then used to determine the level of technical risk.
  • A high value of RPN is mitigated until it is acceptable. In fact, the primary purpose of the FMEA is to identify the high risk (high RPN) attributes, so that preventitive action can be taken.

Differences

There are several important differences in the scoring between the types of FMEAs.  Again, we will focus on the differences between Design FMEA and Process FMEA since the other types are variations of these two.

  • In the Design FMEA types, the probability of occurrence is based upon the likelihood of the failure occurring to a customer, while with the Process FMEA, the probability of occurrence is based upon the likelihood of the problem occurring during the internal process operations, such as manufacturing.
  • In the Design FMEA, the detection capability score is focused on being able to detect this type of failure during the development analysis, and testing – showing an inherent weakness in the design.  In the Process FMEA, the detection capability is based upon determining if the problem has occurred during the production of that specific unit.

Hints & tips

  • Don’t get too worried about the specialty FMEAs (Concept, machinery, application).  If you did a standard Design FMEA or Process FMEA, you would still have a good analysis.
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  • 00:04 Hi, I'm Ray Sheen.
  • 00:06 There's actually several different types of FMEAs.
  • 00:09 Let's look at the differences.
  • 00:10 There are five types of FMEAs that are used, each with a different application.
  • 00:17 Let me quickly talk to all five and
  • 00:19 then we'll focus in on the most commonly used ones.
  • 00:22 The Concept FMEA was used early in design process to assess different system
  • 00:26 concepts.
  • 00:27 Its goal was to identify major problem areas before detail design is started.
  • 00:32 The Design FMEA is used to analyze product or services, it is the most commonly used
  • 00:37 FMEA and is used extensively in aerospace, automotive and medical device industries.
  • 00:42 It will identify problems and
  • 00:44 can be used to determine critical design characteristics.
  • 00:48 The process FMEA is the next most commonly used FMEA.
  • 00:51 It analyzes process steps to determine what could go wrong at each step.
  • 00:55 And, of course,
  • 00:56 it will then identify the critical characteristics associated with each step.
  • 01:01 The Machinery FMEA is a special case of the Process FMEA
  • 01:05 that focuses on what equipment does.
  • 01:07 In addition to failure of the processing by the equipment,
  • 01:11 it's used to help identify reliability in lifecycle issues for the equipment.
  • 01:15 The final one to mention is the Application FMEA.
  • 01:18 This is a special case of a design FMEA and
  • 01:21 focuses on how the customer uses the product.
  • 01:24 This is particularly helpful for products that may be used for unintended purposes.
  • 01:29 You'll identify possible harms and hazards for the customer and
  • 01:32 insist in designing safeguards.
  • 01:35 Many times this FMEA is done after product launch
  • 01:38 based upon how customers are now using the product.
  • 01:41 One of the types of FMEA that we will focus on in this course
  • 01:45 is the Design FMEA.
  • 01:46 This analysis is most useful when done during a detailed design state of
  • 01:50 a product or service during the development project.
  • 01:53 At that time, design trade-offs can be made to reduce overall product or
  • 01:57 service risks of harms or
  • 01:59 hazards without significantly impacting product performance.
  • 02:02 The second type of FMEA that we'll focus on in this program is the Process FMEA.
  • 02:08 This one is particularly helpful with Lean Six Sigma projects.
  • 02:11 When a problem has occurred in a process the Process FMEA can indicate some likely
  • 02:16 causes or failures that could create the problem.
  • 02:19 In addition, since the process improvement developed during the Lean Six Sigma project
  • 02:24 will likely change some parameter of a process.
  • 02:26 The Process FMEA should be updated to reflect the new process and
  • 02:30 minimize the chance of unintended consequences.
  • 02:35 Since our emphasis is on Design and
  • 02:37 Process FMEA, let's compare these two types.
  • 02:40 First, the similarities.
  • 02:42 Both types of FMEAs will list failure modes, the effects of these failure
  • 02:46 modes when they occur and possible causes for the failures.
  • 02:50 Both types will evaluate for severity, probability of occurrence, and
  • 02:54 the ability to detect the failure, although the actual criteria used in each
  • 02:58 one will be slightly different to reflect whether the evaluation is
  • 03:01 at a product performance level or with the process performance.
  • 03:05 Both types can be used to identify critical characteristics, that can then be
  • 03:08 called out in the process documentation and monitored in the controlled plan.
  • 03:13 Generally, the severity scores are the same in both the Design and
  • 03:17 the Process FMEA, which simplifies the creation of the Process FMEA,
  • 03:21 which is normally done after the Design FMEA.
  • 03:24 In both cases, a unique risk priority number, or RPN, is determined for
  • 03:29 each unique failure occurrence detection combination.
  • 03:32 That RPN number is then used to prioritize improvement decisions.
  • 03:36 The high values of RPN must be mitigated to an acceptable level.
  • 03:40 Now, let's consider what's different.
  • 03:42 These differences are primarily their areas of scoring the probability of
  • 03:46 occurrence and the ability to detect the problem.
  • 03:49 For Design FMEA, the probability is based upon
  • 03:52 the failure occurring at the customer or point of use of the product or service.
  • 03:58 So we evaluate our understanding of the design and its application.
  • 04:02 With Process FMEA, the probability of occurrence is based upon creating
  • 04:06 the failure mode during the processing operation such as production.
  • 04:11 Design FMEA detection is based upon being able to determine, while designing
  • 04:16 the product or service, whether the failure mode is inherent in the design.
  • 04:20 It's really looking at the robustness of the design and
  • 04:23 development process that is used.
  • 04:24 While for a Process FMEA detection is based upon the ability to detect
  • 04:28 the failure as it has occurred during the processing of the product or system.
  • 04:34 It's closely tied to the operational control of the process.
  • 04:38 Later in this program, we will go through the details of how to create and
  • 04:41 score both the Design FMEA and the Process FMEA.
  • 04:45 Even though we won't be addressing the other types
  • 04:47 since these are based upon either a Design FMEA or
  • 04:50 a Process FMEA it's not difficult to understand how to do those analyses.
  • 04:55 These are the primary types of FMEA.
  • 04:59 Now some organizations have further created their own customized FMEAs for
  • 05:03 the products or processes, but
  • 05:05 they're still based upon either a Design FMEA or a Process FMEA.

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