Design Review Based on Failure Mode
Failure detection aided design change or Design Review Based on Failure Mode (DRBFM) is a development method that accompanies the development process of a process / product. It is used as part of quality management for preventive error avoidance.
origin
Design Review Based on Failure Mode was developed by Toyota and is being used successfully there. It arose from the knowledge that changes contain the highest potential for errors and was largely derived from the FMEA ( Failure Mode and Effects Analysis ).
Definition of terms
The acronym DRBFM stands for "Design Review Based on Failure Mode" and shows the essential elements in the process:
- DR = Design Review: Review of the development by internal and external experts (customers, suppliers) who are not themselves involved in the project.
- BFM = Based on Failure Mode: Means that experts think about the possible errors related to this change, store these errors in a form, evaluate them and, if necessary, derive measures. The inventor of the method, Tatsuhiko Yoshimura, first tried to convince the engineers to do a creative design review using an FMEA form, but found that the design review was not creative due to the formal structure of the FMEA form.
Action
In contrast to FMEA, DRBFM does not usually work with moderators. However, technical specialists with a corresponding mindset are required. The DRBFM method is not a further management tool, but is a tool for generating a robust design during development. This means that DRBFM is a method used by the developers and engineers to achieve a robust design in the early stages of product creation.
The implementation takes place on a worksheet, preferably printed out in DIN A0 format, in order to create a collaboration with a high information content in an active discussion.
methodology
The DRBFM focuses on changes in the derivation (to be seen here in a broader sense: a new platform or application is also a change). It compares the detailed changes with the functions of the component elements. The changes are fully quantified (e.g. "Wall thickness of the pressure chamber before 1.2 mm, wall thickness afterwards 0.75 mm. Reason: Achieving a 29% lower component weight" instead of "Lower wall thickness". Or "Before: 20 Mantissa bits, afterwards 56 mantissa bits. Reason: Reduction of the signal noise at the output by 14 dB "instead of" higher computational accuracy ").
The so-called "Concerns" are searched for in this matrix. A "concern" is an objection formulated verbally or in writing that describes a potential problem in the design under consideration as a result of change. These (and only these) changes are then transferred to the "Worksheet" (or "Worksheet") and edited. A "concern" is described in a technically exact and comprehensible manner, so that the basic cause of the feared problem can be determined using a "5 × Why" analysis or that it can be shown quantitatively that the "concern" has no or no relevant influence (the design still meets specification after the change).
Fictional example: "By reducing the wall thickness of the pressure chamber to 0.75 mm, there is a risk that in the" casting "production step, due to production fluctuations, impermissible wall thinning or holes are created, so that the component is no longer airtight as specified at 1.2 bar internal pressure (absolute) is ". The "root cause" is determined on the basis of the "5 × Why" analysis. Example: "1. Why can this happen? Because a minimum wall thickness of 0.5 mm is necessary to maintain the internal pressure, but maximum manufacturing fluctuations of 0.3 mm are measured in 2% of the parts manufactured so far. This leads to a Falling below 0.05 mm. 2. Why do manufacturing fluctuations of 0.3 mm occur? Because ... ". As a result, it could be shown in this fictitious example that the "root cause" that will lead to the "concern" is an operating pressure of the casting device that is 15% too low. Whereby the work pressure could demonstrably be 25% higher without any relevant consequences. Based on a plausible design rule, this higher pressure would lead to a reduction in the maximum fluctuation to 0.1 mm.
In the review, the focus is on additional measures in design, testing or production. For the fictitious example, it would be conceivable, as a measure to eliminate the problem, to increase the working pressure of the casting device by 25% and to define a procedure which quantitatively proves the effectiveness of the measure taken.
Publications
- Beginners Guide to DRBFM, Toyota, Nov. 2005
- SAE J2886, SAE International Standard, 2013
