Design Review Based on Failure Mode

Changes to current series production often have high and underestimated risks. is the defining tool for anticipating potential malfunctions and their consequences in the development process. Does this also apply to easily "manageable" design changes?

Fig. 1: DRBFM analyzes "Intended design changes": A positive connection becomes a frictional connection (source: Dietz Consultants)

1. Objective (Why?)
Function and interface X.
The functional transition at the interface X can be "solved" by constructive design of the components A and B.
However, the functional transition can also be realized with auxiliary components (bolt and nut) which are not themselves in the force flow.

Prof. Tatsuhiko Yoshimura (Toyota) came to the conclusion when applying FMEA in "Design Reviews" that the following aspects can complicate its application:

FMEA does not have a specific focus on changes and their consequences.
The complexity of the FMEA can interfere with the developers' focus on the changes.
FMEA may steer developers' thoughts too quickly in one direction during the creative phase of the design change.

This motivated Prof. Yoshimura to develop an independent method, but one that is closely related to .

Objective of the DRBFM method:

Identification of defects resulting from intended changes.
Identification of resulting unintentional changes to the product and the process

2. Procedure (How?)
Strengths DRBFM:

Least possible formalism.
Concentration on problem solving by focusing on changes
Stimulating creativity through appropriate work tools and procedures

and contents are partially compatible. The two methods complement and enrich each other. Nevertheless, the orientation of the methods is different:

FMEA is strong in identifying all potential causes (for potential non-performance of a function).
DRBFM is strong in the identification of all conceivable consequences of a (desired) change.

Areas of application of DRBFM

Changes to the system, subsystem, component
Application projects and variants
Changes in requirements and functions
Changes in manufacturing

How it works!

Assemble an interdisciplinary team.
Realize a creative process in the context of the planned changes to achieve robust products and processes.
Use the appropriate working tools for DRBFM, such as:

Change Checklist (Awareness Sheet)

Contents/Objectives: Identification of intentional and resulting unintentional changes.

Change Comparison Table

Contents/Objectives: Identification of the actual change by comparing the previous design and the changed design.

Function Focal Point Table

Contents/Objectives: Representation of the original functions and the impact of the change on the functions of the product.

Change/Function Matrix (Change and Functions Concern Points Table)

Contents/Objectives: Comparison of functions relevant to the customer and the intended and resulting unintended functions and changes, risk presentation.

DRBFM form

Contents/Objectives: Presentation of changes, the resulting risks and consequences, and the measures developed.

History: DRBFM
Tatsuhiko Yoshimura developed the following method in 1997.The purpose is to find our errors, which occur as a result of intentional changes and the resulting unintentional changes in the product and process.

Features

Less formalism, hence concentration on finding the problem
The working means and the procedure should stimulate the creativity of the engineers
DRBFM was integrated in the GD³ philosophy

Fig. 2: DRBFM FMEA (Source: Dietz Consultants)

What does GD³ stand for?

Fig. 3: DRBFM Mizenboushi Gd3 FMEA (source: Dietz Consultants)

Fig. 4: DRBFM FMEA training (source: DC)

DRBFM Process
Procedural course of DRBFM
Analysis of the change (1-4)

Observation of the desired changes and identification of undesired effects

Analysis of the risks (5-6)

Discussion about the effects on internal and/or external customers

Developing and evaluating solutions (6/7)

The objective is to achieve successfully the desired change and at the same time effectively minimizing the risks.

Defining measures (7)

Based on verfications and validations
Developing and tracking the measures

Success monitoring (8)

DRBFM working means
DRBFM-form sheet

Includes all changes, the risks emerging from them and all measures

Checklist of changes (Awareness-Sheet)

AInstructions to identify desired and resulting undesired changes

Table of changes (Change Comparison Table)

Comparison of the design until now and the modified design, makes the actual change clear

Table of functions (Function Focal Point Table)

Describes the effect of the changes on the product systematically

Matrix of changes/functions (Change and Functions Concern Points Table)

Comparison of the functions relevant for the customer and the desired and resulting changes, thus shows the risks

The DRBFM-form sheet

Fig. 5: DRBFM Formsheet FMEA Mizenboushi GD3 (Source: Dietz Consultants)

Fig. 6: DRBFM Formsheet FMEA (Source: Dietz Consultants)

Analysis of the Cause - Failure – Effect relations.

Presentation: Desired changes and the resulting undesired effects
Presentation: Effects on the function and risks
Determining measures for reducing the identified risks

Fig. 7: DRBFM Formsheet (Source: Dietz Consultants)

Design Review

Presentation: Specification of the required measures and determining the responsibility
Presentation: Evaluation of the effectiveness of the determined measures

The DRBFM-form sheet – Analysis of the Failure chain
1 Description of the desired and undesired changes

Part / Component name
desired changes and reason for changes
Undesired changes, which arise from the desired changes, with justification

Describe all specifications in detail

Fig. 8: DRBFM Formsheet - Components (Source: Dietz Consultants)

2 Description of the function

Describe the function of the part as much precisely as possible
Under which working conditions does the function occur?
Describe all functions precisely

Fig. 9: DRBFM Formsheet - functions affected by the change (source: Dietz Consultants)

3. describe the error possibilities from the change

Describe the risks exactly
Collect other fears in teamwork.

Fig. 10: DRBFM Formsheet - Fears, related to the changes (failure type) (Source: Dietz Consultants)

4 Description of the Occurance and the Failure causes

W-questions: When? / How often? / Where? / …
Negating functions
5 x Why questions (W-method), in order to find out the true cause (measures are effective only if they are directed against the causes)

Fig. 11: DRBFM Formsheet - When and in which form can errors occur? (Source: Dietz Consultants)

5 Consequences

Which consequences arise for the defined customers?

Fig. 12: DRBFM formsheet - implications for the customer (source: Dietz Consultants)

6 Current measures to Prevent Failures

Define measures
Follow thereby the operating conditions and requirements
When required, defined other measures (=>7)

Fig. 13: DRBFM Formsheet - Current design to avoid the errors(Source: Dietz Consultants)

7 Determined measures (Results of DRBFM)

If Point 6: „Present measures“ are not sufficient, additional measures are developed
Naming responsible persons and deadlines

Fig. 14: DRBFM Formsheet - Recommended Measures(Source: Dietz Consultants)

8 Determining effectiveness of the measures

For every measure from the DRBFM, the following is determined what was done, when and how and the results.

Fig. 15: DRBFM Formsheet - Result of the measures(Source: Dietz Consultants)