Step 1: Planning and Preparation
There are five topics that need to be discussed when planning and preparing an FMEA:
Intent Purpose - Why are we doing the FMEA?
Timing Timing - when will it be done?
Team Team - Who needs to be included?
Task - What needs to be done?
Tool - how to do the analysis?
1.?FMEA Purpose
The purpose of an FMEA includes:
Assessing the potential technical risk of failure in a product or process
Analyzing the causes and effects of failure
Documenting preventive and detective measures
Recommendations for measures to reduce the risk
In the case of a medical device, the use of an FMEA is intended to identify medical devices that are at risk. The purpose of FMEA is to discover the potential risks of medical devices, find the sources of hazards, and control the sources of hazards to ensure the safety and effectiveness of medical device products.
2...FMEA Timing
Talking about the timing of FMEA, we need to first understand the circumstances under which FMEA will be used.
New design, new technology, or new process: FMEA is the tool to be used from the very beginning of the development of a new medical device.
New application of an existing design or process: FMEA is useful when a medical device is claiming a new intended use or application site, and new risks need to be considered before the claim is made.
Engineering Changes to Existing Designs or Processes: In order to meet new regulatory requirements, a medical device may need to make changes to its original design, and before doing so, it needs to be analyzed for new risks.
In all three cases, we use FMEA before the product or process is implemented, so FMEA needs to be timely, otherwise it will affect the overall project process.FMEA as a systematic analysis and failure prevention method, it is best to start in the early stages of the product development process.
3.?FMEA team
FMEA is a systematic approach that usually requires a team when implemented. The members of the team must have the necessary expertise, in the same way that we form a risk management team.
What are the members of an FMEA team for a medical device?
Managers: have the authority to decide whether the risks and measures are acceptable or not, and to provide the necessary material or human resources to carry out the project.
Project facilitator: The key is to coordinate and organize the team well, and the leader of the medical device risk management team is a good match for this role.
Design and development engineers: If the medical device involves different systems or working principles, then all relevant design and development engineers need to be involved.
Purchasing: Purchasing has the most say in the selection of raw materials and the corresponding suppliers.
Marketing personnel: including those responsible for after-sales maintenance, on-site installation and other services, is the company's direct contact with the customer channel, their information is equally important.
Customer representatives: if conditions permit, customer representatives can be invited to participate in the medical equipment to meet the needs of customers first.
Suppliers: Some medical devices have components that are produced and supplied by the supplier, and the supplier of this component has the best knowledge of the components they produce.
Technical experts: medical devices are ultimately used in the clinic, so the opinions of experts in the clinical area must be taken into account, which is usually an issue that people tend to ignore.
The composition of the FMEA team is based on the company's own conditions, and how to comprehensively consider the risk is the ultimate goal. After the team is formed, it is necessary to allocate the duties of the members, and it is possible that the responsibility of a certain role is taken by a different person, or one person may take on more than one responsibility.
4.?FMEA Tasks
The seven-step approach provides a framework for FMEA tasks and deliverables, which we will share with you in a subsequent micro-lesson. Each stage should be reviewed for completion by a dedicated person to ensure that each task is completed.
5.?FMEA tools
There are many commercial FMEA software available for FMEA implementation, and the FMEA manual presents us with a view of one as well, and as you can see from the view, this software also follows the seven-step process.
Of course, which tool to use depends on the needs of the organization, and those who are capable can also develop their own.
Step 2: Structural Analysis
Purpose of Structural Analysis
For structural analysis, the same as FMEA analysis of DFMEA and PFMEA, due to the different objects of analysis, structural analysis of the purpose of the structural analysis is also different and similar:
Differences:
DFMEA of structural analysis is to identify and decompose the design into systems, subsystems, components and parts for technical risk analysis.
The structural analysis of PFMEA is to identify the manufacturing system and decompose it into process items, process steps, and process work elements.
Similarities:
Both DFMEA and PFMEA perform a structural analysis to identify each decomposition item and the interrelationships to lay the foundation for the next step of functional analysis.
Structural Visualization
The best way to identify each decomposition item more clearly is to visualize the structure. For DFMEA, it is to visualize the structure of the system, and a common method is to use the block diagram/boundary diagram, structure tree method. For PFMEA, the way to visualize the structure is to use process flow diagram and structure tree. Next, these methods are briefly introduced.
1. Block Diagram/Boundary Diagram
Block diagrams/boundary diagrams are a useful tool for describing the interface between the system under consideration and its neighboring systems, the environment, and the customer. The customer referred to here may be the end user or a subsequent or downstream manufacturing process.
Block diagrams/boundary diagrams are diagrams that show the physical and logical relationships that precede components, with each box corresponding to a component, straight lines that correspond to the relationships or mutual interfaces between product components, arrows on the lines that identify the direction of flow, and dashed boxes that are used to define the scope of the analysis.
Block diagrams/boundary diagrams need to be refined as the design matures, and are created in six general steps:
1) Describe components and characteristics
2) Adjust the boxes to show interrelationships
3) Describe the connections
4) Add interfacing systems and inputs
5) Define the boundaries
6 ) add relevant details in order to determine the diagram
2. Flowchart
You must be familiar with the flowchart, the production process flowchart is a common flowchart we use.
The figure is the production process of electric hospital beds, each production process with a flow chart method to show, it seems very clear.
3.? Structure Tree
The structure tree arranges system elements hierarchically and shows dependencies through structured connections. To prevent redundancy, each system element exists only once, and the structures arranged under each system element are independent substructures.
For DFEMA, the "next lower level or characteristic type" is a separate component. For PFEMA, the "next lower level or characteristic type" is a process work element, and the corresponding process work element is added from "human, machine, material, method, environment and measurement" according to the method of fishbone diagram.
Step 3: Functional Analysis
1. Purpose
The purpose of the functional analysis is to ensure that the appropriate functions are assigned to the appropriate decomposition items. This step follows with the completion of the structural analysis, where we visualize the structure and then visualize the functionality once it is added.
2.? Description of the function
First of all, we have to figure out what is a function? A function of a particular decomposition item describes the intended use of that decomposition item. In DFEMA, the function of a system element describes the intended use of that element. And in PFEMA, it describes the intended use of a process item or process step.
Each decomposition item may contain more than one function, and it is important that the description of the function be clear and accurate. Imagine if the function of a component is not accurately described, the intended use of the component is not clearly expressed, and the result may lead the subsequent analysis in the wrong direction.
When describing a function, you can refer to a format: verb + noun. For example: controlling speed, transferring heat, transmitting power, welding brackets, etc. The reason for describing in this way is to indicate that these functions are measurable.
Example 1: Dental handpiece handle
For example, one of the functions of the handle of a dental handpiece is to connect the head to the connector, and a measure of this function could be to see if the handle connects well to the head and connector.
Example 2: Welding metal
Another example is in the production of electric hospital beds, the function of the welding process is to connect the metal together, and the measurement of the welding process can be measured by testing the results of welding.
3.? Requirements
To determine whether the function of a decomposition item meets its intended use is to see whether it meets the specified requirements. These requirements may come from internal or external sources, and typically include:
Requirements of laws and regulations, medical devices must be safe and effective as required by regulations.
Industry codes and standards, active medical devices have to meet standard requirements for electrical safety and electromagnetic compatibility.
Customer requirements, the design and development of medical devices should take into account customer requirements, customers need to measure blood pressure, we design the device should include the function of blood pressure measurement.
Internal requirements, such as compatibility with other products, some products can be adapted to all other models, some can only be compatible with a few models.
Product characteristics, mainly refers to the significant features of the product, such as the size of the opening, the diameter of the shaft, etc..
Process characteristics, such as freeze-drying process needs to measure the vacuum degree, laminate temperature, etc.
In practice, we need to identify these requirements first, and correspond the requirements with the function.
4.? Functional analysis
Before we visualize the structure, when we do the functional analysis, we can add the description of the functional requirements in the structure diagram, structure tree or flowchart.
Step 4: Failure Analysis
Failure
First let's look at what failure is. Failure is the opposite of function and is derived from function. In the last installment we did a functional analysis and talked about the need to make each decomposition item correspond to a corresponding function.
DFMEA analyzes the function of the object system or part, and their potential failure modes are commonly the following:
Loss of Function That is, inoperative, sudden failure, such as a keystroke malfunctioning
Degradation of Function Loss of performance over time, the batteries in a cardiac pacemaker run out of power
Intermittent Function Randomly when an active medical device is operated start/stop/start
Partial loss of function Loss of performance
Unintended function The device performs an operation without being commanded to do so
Functionality out of range A thermometer that is out of range
Delayed function An electronic external defibrillator that fails to discharge in a timely manner
Analyzing PFMEA looks at the functionality of the process, and their potential Failure modes are:
Non-compliance The production process does not comply with the requirements of the protocol
Inconsistent or partially performed tasks The product flows to the next process without the process check being done
Unnecessary activities The inclusion of unnecessary steps in the production process, instead, introduces new risks
As with descriptions of the function, the descriptions of the failures also need to be Clearly, it is usually composed of a noun plus a description of the failure, such as broken inner packaging or unstable soldering. Try to avoid vague descriptions such as "bad", "broken", "defective", etc.
A function may have more than one failure, when we do failure analysis, we can not be satisfied to find only one failure, to ask yourself "there may be other failures? It's important to ask yourself "Are there any other failures possible?
Failure chain
For each failure, there are three aspects to consider:
What are the effects of the failure?
What was the failure mode?
Why did the failure occur? (cause of failure)
The failure chain is made up of these three elements, which are related
The impact of failure is the consequence of the failure mode, and needs to take into account a variety of impacts, including:
End user
Internal customer (follow-up)
External customer (next tier/distributor/OEM)
Product
Applicable Regulations
The specific impact of failure depends on exactly what kind of medical device the company produces and what the process of production is. As you can see here, a FEMA analysis requires a team, and the team members need to cover the life cycle of the medical device.
Failure modes come primarily from function, and there are many different kinds of medical devices, all with their own unique components and production processes. Let's go through a few examples to show how failure modes can be clearly characterized.
Component deformation
Part oxidation
System cannot withstand sterilization temperatures
Incomplete sterilization
Loss of labels
Analyzing the multiple failure modes that can occur against the function is key to failure analysis.
The cause of failure is the reason for the failure mode, and the failure mode is the consequence of the cause of failure. The causes should be listed as concisely and completely as possible so that measures can be taken later.
When doing a DFEMA analysis, we can look for the causes from the following aspects:
Inadequate design of functional performance e.g. use of biotoxic materials, resulting in biocompatibility does not meet the standard requirements
System interactions e.g. problems with the interface connection between the system
Changes over time e.g. the sterilized packages gradually lose the sterility barrier over time
Changes over time e.g. the sterilized packages gradually lose the sterility barrier over time. Inadequate design to cope with the external environment e.g. whether the environment in which the device is used is likely to have an impact on the performance of the device itself, and these environmental factors need to be taken into account
End-user error For device risk, reasonably foreseeable errors in use need to be identified, and the device needs to meet the requirements for usability.
Unreliable manufacturing design The design and manufacturing process is not validated, and manufacturing may result in parts wearing out and nonconformities occurring but not being detected.
Software problems Software is prone to bugs, which can affect the performance of the device.
When doing PFEMA analysis, we can use the fishbone diagram method to analyze from several perspectives:
Personnel: Are operators and maintenance personnel trained? Do they understand the SOP protocols?
Machine/equipment: production equipment, inspection equipment can be used normally? Is the inspection equipment within the calibration validity period?
Materials: Are key raw materials and auxiliary materials available in sufficient quantities? Are the correct materials being used?
Environment: Are products requiring temperature, humidity, and microbial contamination manufactured in the specified environment?
Regulations/Standards: Sterile medical device production is to be done in a clean room.
Testing: Is the testing of raw and auxiliary materials, semi-finished products and finished products carried out in accordance with the specified requirements?
Failure Analysis
Failure analysis involves linking the effects of failure, failure modes, and causes of failure by answering two questions:
Why do failure modes occur?
What happens when a failure mode occurs?
Failure analysis can also be set out in the form of a structure tree, structure diagram, which makes it easier for everyone to do the analysis, but also leaves the appropriate records. Here's a simple example:
Step 5: Risk Analysis
Previously, we analyzed failure modes and found the effects and causes of failure. The next step is Risk Analysis, which aims to assess the risk by rating the severity, frequency, and detectability, and prioritizing the actions that need to be taken.
Severity Rating S
First, let's look at how to rate severity, which is the severity of the impact of a failure, or in the case of a medical device, the consequence of an injury occurring.The FMEA manual categorizes severity into 10 levels based on the magnitude of the impact of the failure.
In a DFMEA analysis, failures are failures from components or systems that affect the final product. So when doing a severity rating, it's looking at the impact on the product. For medical devices, it's looking at whether the safety and effectiveness of the device is affected.
In PFMEA analysis, the object of failure analysis is the process, and the failure of the process may affect the next process, the next level of product processing, and ultimately the function of the product.
Frequency Rating O
Frequency is the frequency of occurrence of the cause of the failure, or in the case of a medical device, the probability of the injury occurring. The magnitude of the frequency is related to the presence of preventive and detective controls. The more controls that are in place, the lower the corresponding frequency of failure.
Preventive controls provide information or guidance and are inputs to the design. a DFMEA may include: regulatory and standards requirements, standards for materials used, documentation requirements, past experience, etc. a PFMEA may include: SOPs, equipment maintenance, personnel training, etc.
Detection control describes established procedures for verification and validation. dFMEA may include: functional testing, environmental testing, durability testing, design of experiments, etc. PFMEA may include: random testing, functional testing, visual inspections, etc.
Frequency ratings are similarly divided into 10 levels according to the manual.
Detectability Rating D
Detectability is the degree to which the cause and/or mode of failure can be detected, in terms of whether there is a valid and reliable test or inspection method to detect the failure mode or cause of failure. When rating detectability, the primary focus is on the maturity of the detection method and the opportunity for detection. For example:
Testing or inspection methods that are validated are more detectable than those that have not yet been established.
There are failures that can be observed visually, which are certainly more detectable than those that require instrumentation.
Detectability ratings are also categorized into 10 levels.
Measure Prioritization AP
Measure prioritization is the decision to prioritize the measures to be taken prior to taking measures to reduce the risk due to limitations in resources, time, technology and other objective factors.
Judging the priority is mainly through the size of the value obtained by S * O * D, but the new version of the manual has a new provision for this, the first consideration is the severity, followed by frequency, and finally the degree of detection, which is different from the previous only compare the size of the value, to avoid the product of the same value and affect the priority ranking.
The last two steps: optimization and documentation of the results
1.0 Optimization
First, we will look at the optimization of the FMEA analysis in terms of the purpose of the optimization and the implementation of the optimization, respectively.
1.1 Purpose of Optimization
As is customary, let's first define the purpose of optimization. This is the AP table of the FMEA that we showed you in the last issue of Risk Analysis, and the AP table identifies the measure priorities. The purpose of optimization is to identify risk reduction measures based on the risk analysis and evaluate the effectiveness of those measures.
Risk reduction is about reducing the severity of a risk, reducing the frequency of a risk, or increasing the detectability of a risk.
1.2 Implementation of Optimization
In the implementation phase, the following five things are done:
Identify the necessary measures to reduce risk
Assign responsibilities and deadlines
Implement the measures
Evaluate the effectiveness
Continuous Improvement
Identify the necessary measures to reduce risk
Identify the necessary measures to reduce risk
We said earlier that risk reduction is about reducing severity or increasing detectability. p>We said earlier that risk reduction starts from three aspects: severity, frequency and detection. According to the principle of prioritization of measures, the order of optimization is also to eliminate or mitigate the severity first, followed by reducing the frequency, and finally improving the detection.
Reducing severity is relatively difficult because severity is usually qualitative and it is difficult to radically reduce the nature of the event. But it is not completely impossible to do, for example, electric shock injury is the most likely to be fatal, we can change the net power supply of alternating current (AC) to direct current (DC) from the battery, without affecting the safety and effectiveness of the device, the severity is greatly reduced.
Reducing the frequency We take measures on the design and process mostly to reduce the frequency of failure, such as endoscopic light source can be used to adopt a longer life of the cold light source, to increase the time of use of the light source, so as to reduce the frequency of failure of the light source; wear and tear of the mechanical parts of the more wear-resistant materials to increase the number of times the parts are used, so as to reduce the frequency of wear and tear of the parts lead to device failure. The frequency of instrument failure due to wear and tear of this component is reduced.
Improving detection? Improve detection by refining your testing capabilities and establishing sophisticated testing methods. For example, adding an ethylene oxide sterilization indicator card to an ethylene oxide sterilization process can improve detection.
Because it will involve factors such as resource allocation and staff cooperation, the measures developed will need to be reviewed before finalization.
Assigning Responsibilities and Deadlines
Assign risk reduction tasks to different members of the team and set deadlines for completion.
Implementing Measures
Measure implementation is something that needs to be tracked and executed, and there are five types of measure statuses:
Not Yet Determined Measures Not Yet Determined
Not Yet Decided (optional) Measures have been identified but not yet decided upon, and a decision document is being created.
Not yet implemented (optional) A decision has been made on the measure, but it has not yet been implemented.
Completed The Completed status means that the measure has been implemented and the effectiveness of the measure has been demonstrated and documented, and a final assessment has been performed. This is similar to FMEA closure.
Not Implemented The decision not to implement a measure
The status of measure implementation should be documented for tracking and management purposes.
Effectiveness Assessment
When the measure is completed, the frequency and detection are reassessed to see if the implemented measure reduces the frequency or increases the detection. If the effectiveness does not meet the target (which is to be set by the organization itself), then new measures are to be tried until the risk is reduced to an acceptable level.
Continuous Improvement
We all know that risk management is carried out throughout the life cycle of a medical device, so the analysis of risk is ongoing, and that requires continuous improvement to reduce the risk of the device.
2.0 Documentation of Results
The seventh step of FMEA analysis is documentation of results, which in fact cannot be considered a separate step, because throughout the FMEA analysis process, we have to leave the appropriate records, which is the most basic requirement of the quality management system. The new FMEA manual provides us with a series of forms in the appendix, which can be converted into your own corporate records if necessary.
The final FMEA analysis can result in a series of reports that can be used as inputs to the design development documentation.
3.0 Review
After seven installments, with you to understand the seven steps of FMEA, we briefly review. FMEA is the abbreviation for Failure Mode Effects Analysis, is a risk analysis of a method, commonly used is DFMEA and PFMEA. DFMEA is analyzed from the design point of view, and PFMEA is analyzed from the process, the seven-step process. Including:
Planning and preparation
Structural analysis
Functional analysis
Failure analysis
Risk analysis
Optimization
Results of the documented
After the seven-step method, we can to a certain extent, the risk of the instrument identified, and the development of measures to reduce the severity of risk and the frequency, improve detection, and ultimately, the risk of the device. frequency, improve detection, and ultimately form an FMEA report that can be used as input for design and development.