The objective of FMEA is to capture the aspects of potential product or process failure, including:
- What may go wrong (The failure mode)
- What the result of the failure may be (the effects of failure)
- How severe the result of the failure may be (the severity of failure)
FMEA assessments often require multi-disciplinary teams with a diverse understanding of a process, including design, manufacture, quality, testing, reliability, maintenance, purchasing, sales, marketing and customer service. These experts will determine the scope of the FMEA, which can then be detailed in an FMEA table, showing potential failures and consequences.
The FMEA assigns a numerical value of between 1 and 10 to the severity of the failure (S), the occurrence of the failure (O), and the likelihood of the failure being detected (D). Within these numerical values, 1 shows a low impact and 10 is the highest impact. The values are specific to each business but will encompass existing design controls, QA systems, process controls or inspection procedures, to show how likely it is that a given failure mode will be detected or predicted.
By multiplying the values (S x O x D), a risk priority number (RPN) is created so that work can be prioritised according to the severity and likelihood of failure. This allows recommended actions to be taken. The corrective actions can be design or process related as well as improving detection.
The live failure mode effects analysis document can be updated and used for derivative products as well as providing a store of organisational design or process knowledge. This document will include the occurrence ranking, detection ranking, and process controls to prevent the failure from occurring. The failure mode may also have a critical characteristic associated with it, meaning that there is a need to comply with regulations that use special controls. Critical characteristics will usually have a severity rating of 9 or 10 and occurrence and detection ratings above 3. Severity ratings of 8 or 9 in the DFMEA are usually highlighted for action regardless of the total RPN, as they are deemed critical.
FMEA is necessary in a range of situations related to products, processes and services, whether they are new or being adapted or redesigned for a different purpose. It is also worth undertaking FMEA periodically through the life of a process, product or service to ensure it is still effective and safe.
FMEA should be used:
- When a product, process or service is being designed or redesigned following a quality function development
- When an existing process, product or service os being applied in a new manner
- Before the development of control plans for a new or modified process
- When planning improvement goals for an existing service, product or process
- When assessing a failure in an existing process, product or service
- To periodically assess a process, product or service
FMEA was developed in the 1040s by the U.S. military as a method to eliminate the root causes of malfunctioning munitions. This led to the development of a method known as MIL-P-1629, and soon saw FMEA adopted by the nuclear and aerospace industries.
NASA credits the use of FMEA for the successful moon landings and also used a version of the procedure called HACCP (Hazard Analysis and Critical Control Points) to prevent food contamination on space missions.
Ford used FMEA in the 1970s to address a problem with the Ford Pinto that was causing fatal fires following the splitting of petrol tanks. FMEA managed to solve the problem as well as other design difficulties across the company.
In 1993, FMEA was incorporated into the automotive industry’s QS9000 standard for production. The QS9000 standard later became TS16949 and then, in 2016, IATF16949.
FMEA has also been used for semiconductors in the oil and gas industry, and for white goods and common electronic products, among other uses.
As mentioned above, FMEA was originally developed by the military, but since then it has been used by a wide range of industries, from semiconductors in oil and gas to food services, healthcare, plastics and even software.
Toyota expanded on FMEA to create its own Design Review Based on Failure Mode (DRBFM) approach, which is now supported by the American Society for Quality.
However, standard FMEA as well as Failure Modes, Effects and Criticality Analysis (FMECA) struggle to model product failure mechanisms without specialised software. As a result, Failure Modes, Mechanisms and Effect Analysis (FMMEA) is often used for critical procedures like virtual qualification, root cause analysis, accelerated test programmes, and remaining life assessment.
FMEA is used across a wide range of industries from healthcare and manufacturing to software development and for a range of product and process life cycles. It is important for any industry to be able to discover failures, or potential failures, as quickly as possible so they can be mitigated against to improve safety and quality, save money and please customers.
Some example uses of FMEA include:
FMEA is used in agriculture for environmental, ethical and legal reasons, including assessing the environment, machinery and manufacturing processes as well as product quality.
Healthcare applies FMEA as a tool to identify processes that need improvement to reduce risks to both patients and staff.
Manufacturing uses FMEA widely to anticipate and eliminate potential failures in procedure and products. This avoids having to take on expensive corrective actions later and creates reliable, high-quality products to satisfy customer demands.
FMEA in software development is used to improve quality, reduce costs and lower defect density to provide effective products for end-users.
Transport and Logistics
FMEA is also used to evaluate and improve logistics and supply chains to deliver a high-quality service to customers.