DRBFM, Design Review Based On Failure Mode, is a risk analysis specific to design processes..
The DRBFM is a methodology to identify the consequences of changes in products and processes. This method was developed by Tatsushiko Yoshimura, a quality expert and professor at Kyushu University in Japan. He developed it in accordance with the philosophy of Mizenboushi, starting from the observation that the design problems will appear when the changes have not been properly studied and documented. This method makes it possible to anticipate problems in projects for modifying products or processes.
The DRBFM is a methodology with a creative approach, relies on a multidisciplinary team and whose formalism is reduced. On the basis that many problems are due to communication problems between people and between service 1 , the DRBFM makes the link between design, validation, production and quality.
The tool is broken down into 3 distinct phases according to the following diagram :
Phase 1: The preparation
Before you begin the actual work of looking for failures, you need to gather the data and structure it. We will collect data on customer expectations in terms of function, usage, performance, reliability … The project pilot must document all of these elements and collect data on the parts of the product (plan, characteristics technical …).
At this level, we must take into account all the possible changes: intentional changes and a”ccidental changes” 4 :
- Changes intentional : these are changes made by the designers themselves (change of materials, shape, addition of a function …).
- Changes accidentals : they are due to changes in the conditions of use of the product. We then find the parameters such as temperature, humidity, constraints … We must consider all the possible conditions that the product may face.
To carry out this preparation, the project pilot will use the 2 tools below :
The list of changes
It is a table listing the different changes between the current model, the new model and if possible a competing model. It brings good visibility of what is happening.
|Ex : material, viscosity…|
The change matrix will cross the different changes with the product functions. This is to analyze the possible interactions and see where the changes can have consequences.
|Modified part 1|
|Modified part 2|
Phase 2 : Creative FMEA
This work is done in a team, in a dedicated room, where we will disassemble the product, modify it and compare it to the current product. It is important to be able to work on a physical prototype to better visualize changes and exchange more effectively.
The team consists of the staff of the design office but also staff of other services such as production or marketing. Preferably, clients and technical experts are included for complex topics.
The goal is to build a first FMEA :
1. Component name
3. Failure mode
4. Cause of failures
5. Customer impact
1. Identify the modified parts
List the names of the components that have been modified. Based on the data from the preparation phase, the project group will structure and list the modified components. We can also note the reason for the change of this component.
2. Name the functions
Annotate the function of the component using a verb. Indicate measurable data for this function such as a roughness coefficient … Use the data prepared to put the stresses in which the part will be subjected (humidity …).
3. Identify failure modes
We will analyze the possible failure modes with respect to the expected environment and ” accidental ” in which they are used. Also, you must have ” the eye of the customer ” to identify all sources of dissatisfaction :
- Obvious dissatisfactions: breaks, a distortion …
- Unsatisfied tacitness: noise, difficulty of use…
4. Identify the causes of the failures
For each failure, identify the cause of their occurrence using the tools of the problem solving.
5. Identify the impact on the customer
For each failure, we identify its impact on the customer.
The tool is open and offers 2 ways to perform the failure assessment.
The traditional method
In the same way as a FMEA, we will perform an evaluation of several criteria on a scale of 1 to 9 :
- Frequency: we will evaluate the frequency appears the failure (1: rarely, 9: Frequently).
- Detectability: the level of detection of the cause of failure is assessed (1: easily detectable, 9: undetectable)
- Severity: we evaluate the impact on the customer of the failure (1: little impact, 9: very important).
The criticality of the failure then being the multiplication of these three factors.
The DRBFM method
In the method DRBFM proposes a lighter version of the evaluation of criticality. It consists of simply evaluating the impact on the customer of the failure according to the following scale:
- A : high impact, the failure generates safety problems or no longer allows the use of the product.
- B : Medium impact, failure reduces product performance but remains usable.
- C : low impact, the ” comfort ” functions are less efficient but the product is usable.
7. Prepare design review
Last step of the creative FMEA, we will develop a document that will allow us to follow our actions throughout the design process.
6. Solution to avoid failure
7. Design review
8. Validation review
9. Production review
6. List solutions to avoid failure
We will list all the solutions to avoid the failures identified during the creative FMEA.
7. Actions reviewed during the design phase
We will describe precisely the action (s) necessary for the design of the implementation of the solution. For each action, a manager and a date is identified.
They will be verified during the review 1 of the process.
8. Actions reviewed during the validation phase
We will indicate the actions that allow us to validate the design plans of the first prototype. For each action, a manager and a date is identified.
They will be checked during the review 2 of the process.
9. Actions reviewed in production
We will indicate the actions that allow us to validate the pre-series model. For each action, a manager and a date is identified.
They will be checked during the review 3 of the process.
Last step of the DRBFM, we will describe what we will have to do to validate the pre-series model and authorize the launch in production. for each action, a manager and a date is identified.
They will be verified during the review 4 of the process.
Phase 3 : Design Review
Each design review is done in a group, with the presence of managers and clients. Their number differs according to projects, companies … At Toyota, there are 4 design review3 :
This first review uses the data in column 7 of our document. We will check that the solutions to implement during the product design have been made. We check the plans, the different simulation calculations before the final design of the prototype.
The document is updated if necessary.
This second review uses the data in column 8 of our document. The objective is to validate the final plans of the prototype.
The prototype is built, this third review takes up column 9 of our document, and aims to evaluate its performance and the confirmation of the quality of the countermeasures. A final assessment of failure modes is made through the use of the DRBTR. This confirmation allows us to launch the production of the pre-series.
Last design review before production is the confirmation of the pre-series. We will complete column 10 by reporting the final results of our actions. If the results are positive, we authorize the launch in serial production.
1 – Y. Hatamura (2002) – Learning from failure
2 – R. Schmidt, G. J. Riedel, K. Kangas (2011) – Risk assessment using Design Review Based on Failure Mode
3 – R. Laurenti (2008) – Apresentacao de um método para a melhoria do processo de desenvolvimento de novos produtis
4 – H. Shimizu, T. Yoshimura (2004) – Reliability problem prevention method of stimulating creativity and visualizing problem
E. Rebentisch (2005) Lean Product Development
H. Noguchi, Y. Otsuka, H. Shimizu (2010) – Design review based on failure mode to visualise reliability problems in the development stage of mechanical product
Mizen Boushi – Toyota’s quality problem prevention method
S. Kano, H. Shimizu (2001) – A guide to GD3 activities and DRBFM technique to prevent trouble
R. Schmitt (2009) – Lecture quality management