A Guide to GD3 Activities and

DRBFM Technique to Prevent Trouble

Shigeto KanoHirokazu ShimizuReliability and Strength,Vehicle Technology Dept No. 1

Ver.　　　　5.0

How to Implement GD3 Activities and DRBFM

The first invariable principle in ensuring reliability in product development is to"make no changes." You should keep this in mind.Although the principle is to "make no changes," we understand that you havemany things to change when producing a new design. That is what you mustpay attention to. The concept of GD3 to note the changes and use techniquesdifferent from conventional techniques for controls and checks, thus achievingthe high goal of preventing the outflow of the problems encountered.

The changes you must note are "what a designer changed deliberately" and"what changed" in loads and environmental conditions imposed on a specificcomponent due to ambient conditions despite the lack of change in thecomponent design. The DRBFM technique is to use the FMEA, DesignReview and other techniques (which have so far been used for controls) astechniques for creation (for awareness).

The first requirement to complete a product in a short development period is toproduce a design with few problems, or a good design. To that end, it isimportant to "make no changes" that are unnecessary. You should alsoidentify problems in the first stage of development. To that end, it is importantto have a good discussion on the design and conduct a good design review bycarefully examining the test results and tested article. The GD3 is a techniquethat organizes all these.

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ContentsSection 1. What is the GD3 (G.D. Cube)? 3/39

Section 2. DRBFM and creative FMEA for perceptiveness 4/39

Section 3. Timing for the DRBFM 7/39

Section 4. Procedure for the creative FMEA 8/39

1) Preparations2) Fill out an FMEA worksheet one week before the DRBFM.3) Consider the product as disassembled into components. (The key points are the

changed parts.)4) Note the changes (both the changes deliberately made and the changes that resulted

from them).5) Fill out the field for component functions, specifying the functions to be fulfilled by the

components.6) Define the operating conditions of the components. (The key point is the operating

condition that has changed.)7) Note the changes and specify the disorders about the functions and unmarketability.8) Note the changes. Write down in what cases you have concerns and what the factors

of functional disorders and unmarketability (failure mode) are.9) Specify the possible effects of a specific disorder.10) Analyze importance to identify the most important issues.11) Do not overlook the factors related to the manufacturing process.12) Write down what kind of design you have made to eliminate the concerns.

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Section 5. How to proceed with DRBFM 17/39

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Section 6. An embodiment: Hair drier 25/39

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1) Preparations2) Things to be provided on the day of DRBFM3) Readiness for DRBFM (design reviews for perceptiveness)4) Begin debate while noting the changes in each component. (The key point is the

changed part.)5) Note the changes, and discuss if there are any concerns other than those listed in the

worksheet.6) Note the changes. Discuss in what cases concerns will result and the causes of

functional disorders and unmarketability (failure modes).7) Connect the factors about the manufacturing process FMEA.8) Examine the design considerations implemented to eliminate the concerns.9) Discuss design actions and evaluation methods while examining the particular

component and its drawings carefully for each concern and its cause in relation to thechanges.

10) Specify a department responsible, person responsible, and deadline.11) Organize the discussions in the DRBFM and complete the FMEA.12) Check if the items discussed in the DRBFM are actually reflected on the drawings

and evaluation items and effectively "prevent failures."13) DRBFM on the test-completed product14) DRBFM in the manufacturing process

Section 1. What is the GD3 (G.D. Cube)?

The GD3 (G.D. Cube) stands for:・ a good design・ a good discussion・ a good design review

The GD3 is a set of these three elements designed to prevent problems, as you "goback to where you were at the beginning." The GD3, in other words, involves: (1)identifying requirements for a "good design" at the initial stage of development andobserving them, (2) holding a "good discussion" with related departments andcoordinating one another's efforts, and (3) examining the product carefully andconducting a "good design review."

The first invariable principle in ensuring reliability in product development is to"make no changes." You should keep that in mind.Thus, the GD3 recommends in its clause on "Good Design" the practice of"identifying and observing requirements for a basically good design." Although theprinciple is to "make no changes," we understand that you have many things tochange when producing a new design. That is what you should pay attention to.The concept of the GD3 is to note the areas where you must make changes anduse techniques for "taking advantage of the humans' capability of identifying issues(perceptiveness)" different from conventional techniques for controls and checks,thus fulfilling the high goal of preventing the outflow of problems.

The changes are "what a designer changed deliberately" and "what changed" inloads and environmental conditions imposed on the component due to ambientconditions despite the lack of changes in the component design. The DRBFMtechnique is to use FMEA, design review and other techniques (which have so farbeen used as techniques for controls) as techniques for creation (perceptiveness).

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Section 2. DRBFM and creative FMEA for perceptiveness

Conventional design reviews tended to emphasize management. Although they helpedestablish the GD3 in the development process, they are losing its original significance ofidentifying issues. For that reason, we have found a technique for combining creativeFMEA with design reviews, which is a breakthrough from control techniques. We havecome up with a technique of noting the changes, using creativity to discuss even moreissues, and stimulate one another's brains to make one another notice things, thuspreventing problems. We named that technique the DRBFM (Design Review Based onFailure Mode). We believe that the DRBFM links design, evaluation, manufacturing,and quality assurance organically, which makes it possible to prevent problems.FMEA stands for "Failure Mode and Effects Analysis." It means a process of predictingwhat kind of failure is likely to occur, identify the factors of such a failure based onconceivable failure modes, and analyze the degrees of effects. Items that needcorrective actions are subjected to design measures in advance and also appropriateevaluation methods to prevent trouble.These days, the FMEA is actively used to minimize problems that are likely to occur indevelopment and increase development efficiency. The FMEA in the design stage iscalled the Design FMEA (DFMEA) and the FMEA in the manufacturing stage theProcess FMEA (PFMEA).Fig. 1 shows a standard worksheet for use in the FMEA. Many engineers haveprobably seen one before, at least once, and we believe that they understand theusefulness of the FMEA well. However, when you see a form where you must makemany entries, you may lose your motivation at once or you may get preoccupied withthe question of how to proceed with each item. We believe that the reality is that you donot easily start to use it in actual business.Now please think again of the purpose of the FMEA. The FMEA is a method foridentifying conceivable failure modes and preventing trouble. The purpose of the FMEAis not to fill out the worksheet in all entries, thus completing the FMEA form. Theimportant thing is to use your creativity and find a good way to notice many things andlead them to preventing problems. A creative FMEA is a tool for having an effectivediscussion to produce good ideas. Please use the FMEA to have debate first, withoutsticking to the way it should be done.For those who cannot get used to the FMEA, we have provided a new DRBFMworksheet as shown in Fig. 2. It is basically the same as the FMEA worksheet shown inFig. 1. You may use either of them.Section 3 shows the implementation timing for the DRBFM, Section 4 the procedure forimplementing creative FMEA, and Section 5 how to proceed with the DRBFM.

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No. Constituent component

Change and nature of change

Component's functions

Dysfunction and unmarketability due to change (failure mode)

Effect due to disorder

System Vehicle

Factors that produce dysfunction and unmarketability

(cause of failure)

Freq

uenc

y

Reflection on design (design measure)

Reflection on evaluation, quality check

Necessary items of evaluation and check

F M E A WORK SHEET

Fig. 1. A typical FMEA worksheet

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Component Article #Originator; Participants ;

No.;Date prepared;Date corrected;

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No.

Fig. 2. DRBFM worksheet

DRBFM WORK SHEET (For new designs and redesigns )Design Review Based on Failure Mode

Component

ChangeFunction

Concerns over the change

Loss of functionand

unmarketabilitydue to change

Any otherconcerns?(DRBFM) Fr

e-qu

ency

Concerns in what case?

Cause/factor

Any otherfactors toconsider?(DRBFM)

Effects oncustomers

What design was made toeliminate the concerns?

(such as designrequirements, designstandards, and check

sheets)

Recommended actions (DR BFM results)

Items that the DRBFMindicates should be

reflected on thedesign

Activitiesperformed asa result of the

actions

Model ;System ;Component; Originator; DR members;

No.;Date prepared;Date corrected;

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Items that the DRBFMindicates should be

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Section 3. Timing for the DRBFM

Creative FMEAComponents

Changes noted

Concerns over the changes(failure mode)

Causes of the concerns

Design ReviewReflection on the design Reflection on the evaluation

Actions checked

Effects and importance

Fig. 3. Composition and steps of the DRBFM Fig. 4. Timing for the DRBFM

Product planning

Basic design produced

Design

Prototype

Evaluation

Mass-production launched

DRBFM(DR of the prototypediagram )

DRBFM(DR of the officialdiagram after the FS)

DRBFM(DR of the conceptualdiagrams)

The DRBFM switches from the viewpoint of "management" which performs specifiedtasks correctly to the viewpoint of "taking advantage of the humans' capability ofidentifying issues (perceptiveness)." It combines the FMEA with design reviews. Thus, theDRBFM is an unprecedentedly creative technique. Fig. 3 shows the steps of the DRBFM.

Fig. 4 specifies the timings in development for the DRBFM. To prevent problems, it isimportant to implement the DRBFM on prototype drawings on a top-priority basis. It is themost effective way to increase the quality of the drawings. However, since the prototypeis not complete at this point in time, similar components and plastic models (photo-molding) should be provided.These days, because of the need to shorten development time, the DRBFM may beconducted even earlier, that is, in the stage of compiling conceptual diagrams of theproduct. In that stage, which is prior to a detailed design, people have debate mainly as tohow to design the items that one is concerned about. People can consider many designmethods there. In the stage of conceptual diagrams, the DRBFM is a tool that stimulatedesigners' creativity.The DRBFM is a technique that "takes advantage of the humans' capability of identifyingissues (perceptiveness)" to prevent problems. One must constantly examine whether thecorrective actions discussed were actually implemented and whether they provedeffective. For that reason, it is important to implement the DRBFM while actually holdingthe tested product and having a close look at it before the disassembled test product andtest results after the prototype test.

As discussed above, the DRBFM can be conducted about three times or so. In theprocess of development, redesigns may be conducted. Therefore, please conduct theDRBFM flexibly to make sure that the discussed details are reflected in the drawings andevaluation in a timely manner.

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Good Design Review

Preparations for mass-production DRBFM(DR of the permanentmodel )

(Redesign)

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Section 4. Procedure for the creative FMEAShown below is how to fill out a worksheet for the creative FMEA (DRBFM), whichforms the basis for debate at the DRBFM. These steps may be implemented either byindividuals or by groups. They will presumably prove more effective when implementedby a group. However, since many of the explanations are overlapped with the DRBFMto be mentioned later on, this section will mainly show how an individual can fill out aworksheet for the creative FMEA.(People who are to prepare such a worksheet in a group are referred to the DRBFMProcedure.)

No.

Component

Change

Function

Concerns over the change

Loss of functionand

unmarketabilitydue to change

Any otherconcerns?(DRBFM) Fr

e-qu

ency

Concerns in what case?

Cause/factor

Any otherfactors toconsider?(DRBFM)

Effects oncustomers

What design was made toeliminate the concerns?

(such as designrequirements, designstandards, and check

sheets)

Recommended actions (DRBFM results)

Items that theDRBFM indicates

should be reflectedon the design

Activitiesperformedas a result

of theactions

1) PreparationsTo fill out an FMEA worksheet efficiently, organize the following information inadvance:a) Required specifications: Requirements for performance and reliabilityb) Operating environment, destinations, etc.c) Structure of components and functions of partsd) Changes made on the previous version, design considerations

- Identify the changes made for a reason and the changes that resulted from those deliberate changes.--- "What" was changed "how" "for what" and "what resulted" from those changes, for example?

Before beginning work, provide the following:a) Drawings (such as plans, assembly diagrams, component diagrams, and

drawings of old parts)b) Components (The drawings should preferably show the internal structures of such

components.)(If the prototype is incomplete, provide a similar component or a plastic model.)

c) FMEA worksheet (DRBFM worksheet)

2) Fill out an FMEA worksheet one week before the DRBFM.Since DRBFM debate progresses according to the worksheet, the FMEA should beimplemented in advance. However, you do not have to complete the entireworksheet as shown in Fig. 1. If only you have entered some results you have givensufficient consideration to concerning what kind of design you have produced inorder to address the failure mode, its factors, and problems, you can have debate inthe DRBFM over specific corrective actions about "items to be reflected in thedesign" and "items to be reflected in the evaluation." Through debate for the DRBFM,you can also verify the failure mode and its factors again.

3) Consider the product as disassembled into components. (The key points arethe changed parts.)Divide the product to the level of component diagrams and consider it while watchingthe components and component diagrams.

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Items that the DRBFMindicates should be

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4) Note the changes (both the changes deliberately made and the changes thatresulted from them).Most problems occur when a change is made in a conventional design. To proceedefficiently with the FMEA, identify the changes first, then note the changes and considerthe problems. Here, identify all changes that are considered to affect the performance ofthe components.In that case, it is important to remember to check the changes that resulted fromdeliberate changes (such as heatup in the surroundings, the shape of the component incontact with the changed component, a change in material, and a change in oils).

5) Fill out the field for component functions, specifying the functions to be fulfilledby the components.Next, start listing up the functions that the target components are supposed to fulfill.While looking closely at the drawings and components, give sufficient consideration tothe functions of the entire system and the interaction between the components. If youare to conduct the FMEA in the stage of conceptual diagrams where you have notdecided on the details of the components, proceed with the examination with emphasison the functions of the entire system.

6) Define the operating conditions of the components. (The key point is theoperating condition that has changed.)Before noting the changes and considering the possible concerns, consider in whatenvironment the target component will be used, while putting yourself in a customer'sshoes. Examining what kind of stress (operating environmental conditions) the targetcomponent will be subjected to will identify the concerns over disorders about thecomponent functions and their unmarketability.

Photo 1. Filling out a DRBFM worksheet

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7) Note the changes and specify the disorders about the functions andunmarketability.Envisage the various environmental conditions under which the component will be used,then consider what the possible concerns a customer may have as a result of thechanges (those made deliberately and those resulting from them).When you think of the failure mode, you tend to think only of such disorders as damage,distortion and wear. While putting yourself into a customer's shoes, do not forget to listup functional losses and items that may affect marketability, such as "abnormal noise"and "difficulty in operation."You may find it hard to identify all failure modes in a short time all alone. You can alsohave debate in the DRBFM to be mentioned later on. So list up the modes thinking as ifyou were a customer.At the start of a discussion, concerns (failure modes) and their factors come up inconfusion. Do not think too much about which category each item belongs to. Just letwhat comes to your mind come out. If defects expected at first (factors and causes)come to your mind, begin with the next step: "functional disorders and factors ofunmarketability (failure mode)." However, it is important to go back to the start lineagain and again and conduct an examination from scratch to check for any otherconcerns in order to make sure all concerns (failure modes) are identified.

8) Note the changes. Write down in what cases you have concerns and what thefactors of functional disorders and unmarketability (failure mode) are.Finding a way to list up specific factors of failure modes is the key to useful debateabout the subsequent "items to be reflected on the design," "items to be reflected onthe evaluation," and "items to be reflected on the manufacturing process." Do not writedown such generic statements as "defect in ...." Instead, specify "which region isdefective in what way" in relation to a specific change made. While having a close lookat the "component" and "drawing," remember to write down sentences, not words."Writing sentences" should allow you to embody any image you may have in mind andconcretize the phenomenon of a specific defect in your mind.If factors of failure modes are confused and you cannot reach the real cause of aspecific failure mode, you can conduct the Fault Tree Analysis (FTA), thus organizingthe factors of the failure. However, it is basically important to identify the issues andproblems while noting the changes and use your creativity to think of the causes.

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Fig. 5 shows a typical FMEA procedure. It is part of the FMEA used in a design reviewfor considering the use of resin for the lever in the engine room. For each component,the worksheet specifies the component functions, failure modes, causes of the failures,and corrective actions taken. For the corrective actions, the worksheet separates thedesign actions from the actions checked in the test. At a glance, you will find standardand well-organized FMEA results.However, the study results of the cause of failure is summarized with a genericstatement common to all resin parts, "defect in ...." This FMEA does not give any clue tothe molding defects and dimensional imperfections. This FMEA would look naturalenough if the resin lever had been replaced with a resin knob of the parking brake lever.The causes of damage, distortion, and wear are specified with a repetition of identicalwords. The worksheet does not specify problems peculiar to that particular component.This sheet lists up universal factors common to all resin parts. It is a great deviationfrom the purpose of the FMEA which is to make people notice of various issues andproblems and find problems peculiar to the component in relation to the particularchange made.To have useful debate about "items to be reflected on the design," "items to be reflectedon the evaluation," and "items to be reflected on the manufacturing process" in thesubsequent DRBFM requires you to write sentences in a specific manner. You cannotdecide on a specific corrective action unless the cause of the component beingdiscussed is identified.Fig. 6 shows a typical operation where, concerning the cause of the failure, people firstthought of heat, moisture, oils, and other environmental conditions under which theparticular component is used and they progressed in the thinking process to the inputconditions and molding process. As shown in this example, describing in specificsentences the consideration results of the cause of the failure of the particularcomponent will allow one to determine a specific corrective action in the subsequent"items to be reflected on the design" and "items to be reflected on the evaluation."Fig. 7 shows how a DRBFM worksheet was typically used. You can determine a specificcorrective action for "items to be reflected on the design" and "items to be reflected onthe evaluation," along with "items to be reflected on the manufacturing process."

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1 3 1 3

1 3 1 3

1 3 1 3

1 3 2 6 ○

1 3 1 3

1 3 2 6 ○

1 3 1 3

1 3 1 3

1 3 1 3

1 3 2 6 ○

1 3 1 3

1 1 1 1

1 1 1 1

1 1 1 1

1 3 2 6 ○

1 3 2 6 ○

1 1 1 1

No. Region Component'sfunction Failure mode

Cause of failure(initial, deterioration

over time)

Effect of disorder

1 Resin lever( PA66 )

1. Springretention

1. Rupture ofthe bossthat fixesthe springhook

2. Distortionof theboss thatfixes thespringhook

3. Wear ofthe bossthat fixesthespringhook

1. Defective material

2. Defective molding

3. Defective dimension

4. Thermal deteriorationof material

5. Selection of the wrongmaterial

6. Internal residual stress

6. Spring resonance

Effect onassembly Vehicle or E/G

Unable to open Unable totravel

Corrective action

Design action Check method and result

・ Selection of a material that allowsfor deterioration

Fig. 5. A typical FMEA on a resin functional part (1)

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・ A shape design conducted,allowing for residual stresses

・ Durability tests conducted: Noproblems revealed

・ Durability tests conducted: Noproblems revealed

・ Selection of a material that allowsfor deterioration

・ Durability tests conducted: Noproblems revealed

・ Selection of a material that allowsfor deterioration

・ Durability tests conducted: Noproblems revealed

・ Selection of a material that allowsfor deterioration over time

・ Durability tests conducted: Noproblems revealed

1. Defective material

2. Defective molding

3. Defective dimension

4. Thermal deteriorationof material

5. Selection of the wrongmaterial

1. Defective material

2. Defective molding

3. Defective dimension

4. Thermal deteriorationof material

5. Selection of the wrongmaterial

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No.

1

Fig. 6. A typical FMEA of resin functional components (2)

Deteriora-tion overtime

-

Ａ Ａ

Impact Ｂ Ａ

Ｂ Ｂ

Ｂ Ａ

Fatigue

　

Ｃ Ｃ

　

　

Ａ Ａ

　

Ｂ Ａ

Deteriora-tion overtime

Ｂ Ａ

Ｂ Ｂ

　 Ａ Ａ

　

　 Ａ Ａ

Resinlever

Component(region)

Changeand

nature ofchange

Component'sfunction

1.

Functionaldisorder and

unmarketabilitydue to the change

(failure mode)

1.

Effect ofdisorder

System Vehicle

Unabletoopen

Unabletotravel

Factors leading to functionaldisorders and unmarketability

Symptomas a

factorCause of failure

Corrective action

Reflection on the design (design actions)

Rep

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tive Quality check

(check method and result)

Metal toPA

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Perform strength calculations allowing forthe causes of deterioration.* Determine the safety factor.* Perform calculations based on thecharacteristics after deterioration due toheat and grease.Survey the stickable solvents (such as E/Goil, fuel and LLC).

Perform a durability test afterdeterioration.* Durability test after deterioration dueto heat and grease* 100°C x 500 hrsPerform a composite deteriorationdurability test.* Cold and heat: coat with calciumchloride (-35 to 100°C, 95%)Perform a test at the top limit springforce.

Static strength declined and damage resulteddue to resin deterioration.* Thermal deterioration* Grease deterioration* Deterioration due to moisture* Deterioration due to calcium chloride* Deterioration due to E/G oil, fuel, and LLCFatigue strength declined and damageresulted due to resin deterioration.

-

-

-

-

-

-

- Damage due to spring impact

- Cracks resulted from a boss having too smallan outside diameter and the repeatedreaction of the spring.

- A boss bottom with a small radius ofcurvature resulted in stresses concentrated,which then resulted in cracks.

- A high GF fill-up ratio resulted in repeatedloading, which then resulted in fatigue cracksin the boss bottom.

- Dispersions in the molding conditionsresulted in welds in the boss bottom, whichthen resulted in cracks.

- Forcible releasing of the mold resulted incracks in the boss bottom.

Overload

- Resin deterioration resulted in a decline instatic strength and creep strength, which thenresulted in a deformed boss.* Thermal deterioration* Grease deterioration* Deterioration due to moisture* Deterioration due to calcium chloride* Swelling due to E/G oil, fuel and LLCPlastic deformation of the boss due to thespring reaction

- Deformed when the spring was installed.

- Dispersions in the molding conditions (resintemperature and mold temperature) resultedin deformation after the mold was removed.

-

- Deformed due to the orientation of the glassfibers.

Conduct an approximate quote on impactstrength.

-

Conduct a quote on fatigue strength.* Conduct an estimate based on an S-Nchart of stresses generated and PA.

-

Boss radius of curvature: 0.5 or moreindicated in the drawings

-

Consider the optimal fill-up ratio of glassfiber.* Consider static strength, fatigue, andimpact strength.

-

Control the molding conditions thoroughly.* Specify in the QC process chart: resintemperature, mold temperature, injectionpressure, injection speed, etc.

-

Give instructions to check the boss forcracks in an inspection instruction sheet.

-

Perform deformation calculations based ona material characteristics chart afterdeterioration.(A stress-strain curve.)* Consider the outside diameter and heightof the boss.* Give instructions about the tolerance ofthe spring force.

-

Make sure that the instructions are followedin installing the spring.

-

Control the molding conditions thoroughly.* Specify in the QC process chart: resintemperature, mold temperature, injectionpressure, injection speed, etc.

-

Consider the gate position.-

Perform an impact test (at low andhigh temperatures).

-

Conduct a durability test afterdeterioration.

-

Check the dimensions of the sample.-

Perform a durability test on a worst-scenario sample with welds.

-

Check for deformation in a hotatmosphere.Perform a deformation test afterdeterioration (due to heat, grease,and temperature).

-

-

Perform a deformation test on asample under the worst moldingconditions.

-

Check the orientation of the glassfibers. (Consider optimizing themolding conditions.)

-

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Springretention

Damage to theboss that fixes thespring hook

2. Deformation ofthe boss that fixesthe spring hook

[Typical DRBFM cases]

　

　

A

　

　

　　

　　

No.

↑

↑

↑

↑

↑

↑

A

A

A

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A

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1 3 1 3

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1 3 2 6 ○

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1 3 2 6 ○

1 3 1 3

1 3 1 3

1 3 1 3

[Typical formal FMEA cases]

Fig. 7. How a DRBFM worksheet is typically filled out

No. Region Component'sfunction

Failuremode

Cause of failure(initial, deterioration

over time)

Effect of disorder

Effect onassembly Vehicle or E/G

Corrective action

Design action Check method and resultFreq

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Seve

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Failu

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Fata

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1 Resin lever( PA66 )

1. Springretention

1. Ruptureof theboss thatfixes thespringhook

2. Distortionof theboss thatfixes thespringhook

1. Defective material

2. Defective molding

3. Defective dimension

4. Thermal deteriorationof material

5. Selection of thewrong material

6. Internal residualstress

Unable to open Unable totravel ・ Selection of a material that allows

for deterioration

・ A shape design conducted,allowing for residual stresses

・ Durability tests conducted: Noproblems revealed

・ Durability tests conducted: Noproblems revealed

1. Defective material

2. Defective molding

3. Defective dimension

Component (region)

Changeand

nature ofchange

Function

Concerns over the change (failure mode)

Any otherconcerns?(DRBFM)

Any otherfactors to beconsidered?

(DRBFM)Freq

uenc

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Impo

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Activ

ity p

erfo

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as a

resu

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the

actio

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Resinlever

1 Metalto PA

1. 1. Damageto theboss thatfixes thespringhook

Hig

hLo

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ediu

mD

eter

iora

tion

over

tim

eIm

pact

Fatig

ue

Static strength declined and damageresulted due to resin deterioration.* Thermal deterioration* Grease deterioration* Deterioration due to E/G oil, fuel,and LLC* Deterioration due to moisture* Deterioration due to calciumchlorideFatigue strength declined anddamaged resulted due to resindeterioration.

-

-

Damage due to spring impact-

Cracks resulted from a boss havingtoo small an outside diameter andthe repeated reaction of the spring.

-

A boss bottom with a small radius ofcurvature resulted in stressesconcentrated, which then resulted incracks.

-

A high GF fill-up ratio resulted inrepeated loading, which thenresulted in fatigue cracks in the bossbottom.

-

Dispersions in the moldingconditions resulted in welds in theboss bottom, which then resulted incracks.

-

Forcible releasing of the moldresulted in cracks in the boss bottom.

-

Unableto travel

Aromatic PAadopted in viewof thermaldeteriorationanddeteriorationdue tomoisture.

*

Safety factor ofstatic strength>3.0

*

A 3-point gateto be used toprevent weldsand increaseresin fluidity

*

　Perform strengthcalculations allowing forthe causes ofdeterioration.* Determine the safetyfactor.* Perform calculationsbased on thecharacteristics afterdeterioration due to heatand grease.Survey the stickablesolvents (such as E/Goil, fuel and LLC).

-

-

Conduct an approximatequote on impactstrength.

-

Conduct a quote onfatigue strength.* Conduct anestimate based on anS-N chart of stressesgenerated and PA.

-

Boss radius of curvature:0.5 or more indicated inthe drawings

-

Consider the optimal fill-up ratio of glass fiber.* Consider staticstrength, fatigue, andimpact strength.

-

Party

A, M

ar.

Party

A, A

pl.

Party

A, M

ar.

Party

A, M

ar.

Party

A, F

eb.

Perform a durability testafter deterioration.* Durability test afterdeterioration due to heatand grease* 100°C x 500 hrsPerform a compositedeterioration durabilitytest.* Cold and heat: coatwith calcium chloride(-35 to 100°C, 95%)Perform a test at the toplimit spring force.

-

-

-

Perform an impact test(at low and hightemperatures).

-

Conduct a durability testafter deterioration.

-

Check the dimensionsof the sample.

-

Perform a durability teston a worst-scenariosample with welds.

-

Party

B, J

un.

Party

B, M

ayPa

rty B

, Jun

.Pa

rty B

, Apl

.

Sampling inspection(once a month)After thermaldeterioration, adurability test wasconducted.

-

Boundary samples to beused to make sure thatall workers observe therequirements.

-

Items of acceptanceinspection of moldingmaterials to bedetermined andobserved by allpersonnel

-

Molding conditions to becontrolled thoroughly* Specify in the QC processchart the resin temperature,mold temperature, injectionpressure, and injection speed.* Boundary samples to beused to make sure that allworkers observe therequirements

-

Use an inspectioninstruction to instruct thepersonnel to check thebosses for cracks.* Boundary samples tobe used to make surethat all workers observethe requirements

-

Party

C, S

ep.

Party

C, S

ep.

Party

C, S

ep.

Party

C, S

ep.

Party

C, S

ep.

Test inprogress(sched-uled to befinished inJune)

Test inprogress(sched-uled to befinished inJune)

Completed

(14/39)

Loss of functionand

unmarketabilitydue to change

Concerns in what case?

Cause/factor

Effects oncustomers

What design wasmade to eliminate

the concerns? (suchas design

requirements,design standards,and check sheets)

Recommended actions (DRBFM results)

Prio

rity

ratin

g

Rep

rese

ntat

ive

Dea

dlin

eItems that the DRBFMindicates should be

reflected on thedesign

Items that the DRBFMindicates should be

reflected on thedesign

Items that the DRBFMindicates should be

reflected on thedesign

Springretention

Rep

rese

ntat

ive

Dea

dlin

e

Rep

rese

ntat

ive

Dea

dlin

e

9) Specify the possible effects of a specific disorder.For an effect analysis, please list up the possible items from assembly componentsto systems on which the particular part is to be mounted, while putting yourself in thecustomer's shoes.

10) Analyze importance to identify the most important issues.An importance analysis is not conducted to eliminate discussions about "reflectionon the design" and "reflection on the evaluation" in the DRBFM by droppingunimportant items one by one from the particular level. It is conducted to identify themost important issues such as "recall issue" and "vehicle fire" in view of thefunctions of the entire system. Her, divide importance into about three levels (A, B,and C) and check the low-importance item (rank C) well for any hidden problems.In the FMEA in Fig. 5, factors of low importance are not subjected to the subsequentstudies in "items to be reflected on the design" and "items to be reflected on theevaluation." Even if you successfully identify various factors, you may overlooksome hidden important items. Your previous accumulated efforts in FMEA may turninto a waste. Please keep in mind that you must do this to find new issues.

11) Do not overlook the factors related to the manufacturing process.You must also consider variances in the manufacturing process. It is particularly tobe noted that molding conditions and methods of material control may affect theperformance of resin parts. Therefore consider carefully and list up the factorsrelated to the manufacturing process.

12) Write down what kind of design you have made to eliminate the concerns.When you start FMEA, the design examination should be complete. For the causesof any concerns listed up regarding the changes, please write down in advance anydesign requirements incorporated in the design examination and which can besubjected to some corrective action.You are to specify the items already incorporated in the design and items subjectedin advance to a design examination according to the design standards, checklists,preventive information and other documents, in relation with the possible causes.There should be problems that cannot be solved with the design requirementsincorporated in the design examination. Conducting FMEA to identify issues shouldmake items that cannot be detected with conventional checklists come to thesurface.

Component

ChangeFunction

Concerns over the change

Loss of functionand

unmarketabilitydue to change

Any otherconcerns?(DRBFM) Fr

e-qu

ency

Concerns in what case?

Cause/factorAny otherfactors toconsider?(DRBFM)

Effects oncustomers

What design was made toeliminate the concerns?

(such as designrequirements, designstandards, and check

sheets)

Recommended actions (DRBFM results)

Items that the DRBFMindicates should be

reflected on thedesign

Activitiesperformedas a result

of theactions

Rep

rese

ntat

ive

Dea

dlin

e

Impo

rtanc

e

Prio

rity

ratin

g

Rep

rese

ntat

ive

Dea

dlin

e

Rep

rese

ntat

ive

Dea

dlin

eItems that the DRBFMindicates should be

reflected on theevaluation

Items that the DRBFMindicates should be

reflected on themanufacturing process

No.

(15/39)

Organizing the findings obtained so far in a worksheet identifies the concerns to beexpected by noting the changes in the particular part and making the design changes andidentifies the possible causes of such concerns. The design findings obtained so far willalso determine whether such concerns are likely to be solved.

When the DRBFM worksheet has been filled out to this stage, you are to conduct DRBFMin the next step. DRBFM, where active debate is held among the personnel concerned,will identify concerns and specific corrective actions that you did not notice by yourself.This process will then turn into a creative design review for identifying the issues.

(16/39)

Section 5. How to proceed with DRBFM "We have conducted many design reviews in the process of development, but we cannotidentify the issues so easily." "I am not sure if we have detected all issues." Those arecomments we often hear. In such a case, we ask them "Do you find such meetings justfollowing a pattern?" They respond, "Yes, those meetings tend to be places for only reportingwhat is going on." That is the result of continued emphasis on the administrative aspect ofdesign reviews. It has helped establish the concept of design review in the process ofdevelopment, but the result is that the personnel concerned are losing the significance ofidentifying the issues, which significance is what design reviews are supposed to have.We therefore wish to recommend design reviews and DRBFM which emphasize the aspect ofthe design review where "people notice the issues and make corrective actions." DRBFMidentifies all anticipated issues in order to proceed with the debate by means of worksheets.As a result, the design, evaluation, manufacturing, and quality assurance of components willbe organically connected, which will presumably make it possible to "take design measures inadvance to prevent trouble," thus preventing problems.Described below is the DRBFM method of proceed with a design review based on FMEA.

1) PreparationsOrganize information given below and distribute it to the participants in advance in orderto have efficient debate in DRBFM.

a) Requirements: Requirements for performance and reliabilityb) Operating environment, destinations, etc.c) Structures and functions of componentsd) Changes and design considerations in the system

- Identify the changes made as a necessity and the changes resulting from them. --- "What" was changed "how" "for what" and "what changed as a result?" etc.

2) Things to be provided on the day of DRBFMTo start DRBFM, be sure to provide the following:

a) Drawings (such as scheme drawings, assembly drawings, component diagrams, anddrawings of old components)

b) Components (It is better to have cut articles that show their internal structures.)

c) DRBFM worksheets- Worksheets where previous FMEA results are organized should clearly indicate

what are the concerns that are conceivable by noting the changes, what causessuch concerns, and which of the necessary corrective actions can be taken in thedesign examination so far.

- If a prototype is not complete, provide a similar sample, conventional component,or plastic model that allows people to understand the structure and functions of theproduct easily.

(17/39)

3) Readiness for DRBFM (design reviews for perceptiveness)In DRBFM, it is very important for participants to participate actively in debate andexchange ideas, thus stimulating one another's brains and making one another noticevarious things. Described below are the readiness and considerations for joining theDRBFM process, which is a method for perceptiveness (creation).

[What designers should be ready for]Honestly speaking, designers hate to join a design review. "They give us all those stupidcomplaints, give us a ton of homework, and give us no good advice at all. If anybody saysthey know these things better than we designers do, let them dare to speak!" That isprobably what those designers think in their minds. As far as designers think that way, adesign review will not be a success.Being at a DRBFM session, designers should be thinking "they are going to stimulate ourbrains and inspire us." They should organize the items on the agenda for debate at theDRBFM session. If any design review failed to inspire them, they must think that it was theirfault.When having a design review with a supplier, some designers say nothing but "Everything isall right!" whatever the supplier says, because those designers are too interested instressing that their system is problem-free. Such design reviews are a failure.

[What chairpersons should be ready for]It is no exaggeration to say that the success in DRBFM depends on the chairperson of thesession. The chairperson should create an atmosphere where people can relax but have anappropriate degree of tension so that experts' opinions can be heard sufficiently in order toprevent the discussions from going one way. It is important to lead the debate whileconstantly being aware of the need to concentrate the participants' attention to a single pointand then spreading it to the entire spectrum.

[What participants should be ready for]Debate for DRBFM should be joined not only by component designers but also byrepresentatives of the teams for materials, evaluation, manufacturing and other operations.They should discuss what concerns there are from various viewpoints and identify theissues. When joining a design review, are you not having an easy attitude, like "I am goingto get some inputs." When attending a DRBFM session, you should be as ready as to thinkto yourself "I am going to help the designers with my own expertise. Any problem with thissystem would be my responsibility."The number of the attendants should be about 10 or 15 at the most, to make sure that allmembers can join the debate.

　 　　　　

(18/39)

[What you should be ready for when looking at a thing]In a DRBFM session, you will proceed with debate while looking carefully at the drawingsand components. Looking carefully at a thing is harder than you may think. For that reason,you should be ready for what is described below. At a DRBFM session for a test-completeditem, it is important to pick up each component in your hand and look carefully at all itsregions and corners. Make a sufficient check to detect any hidden problems stemming fromdiscoloration and wear.- Looking at things that are seen

Some people look only at the parts that are on the agenda. It is important to look at allthe things surrounding them, covering all corners.

- Looking at things that are hiddenLooking at things disassembled and cut sections is a must for participants other than thedesigners.

- Comparing and arrangingIf you do not notice anything easily when you are handling the article in question alone,arrange good things with bad ones. You can then see the difference.

- Measuring with an easy methodApply a ruler to the component, roll it on a desk, or measure it with an easy method. Youcan then see a lot of things. You can get a lot of information for debate without using anupmarket meter.

[Debate considerations]Described below are the considerations for proceeding with creative FMEA and DRBFM.Use your creativity and notice various factors in debate about the concerns (failure modes)and their causes related to the changes.- First of all, think of the concerns that may result from the changes anticipated, while

putting yourself in your customers' shoes. (Note the changes deliberately made andthose resulting from them.)

- Consider the operating environmental conditions (stresses) and think of the factors,beginning with materials and moving on to the shapes and manufacturing process.

- Have debate about the causes of the variances (such as dimensions and manufacturing).- Think not only of the mechanical factors. Think of the chemical ones as well.

- Note not only those in direct contact. Note the indirect factors as well. (They includeacids, metal ions dissolved in oils and other liquids, adhesion of cleaning agents, andadhesion of machine oil.)

- Note the temperatures from high to low. Pay particular attention to ice and condensation(especially those on electric parts).

- Note the fasteners (such as bolt fasteners, crimping, and snap fits), welds, fused parts(methods and shapes of fusion), and sealed parts. (Note the regions of discontinuity.)

- Discuss the unique methods of the customers.(Have sufficient debate about how the customers will use the product, while puttingyourselves in their shoes.)

* Electric corrosion (the formation of local batteries due to contact between differentmetals and corrosion in the clearance: such as corrosion due to an atmosphere ofacids or alkalis)

* Effects of oils and solvents and those of various additives and fillers* Effects of products generated by deterioration (such as oxides)* For oils and solvents, consider the status of new articles and the effects of

deterioration.

(19/39)

4) Begin debate while noting the changes in each component. (The key point is thechanged part.)In DRBFM, you are to have debate about one item at a time, about the items organizedon a DRBFM worksheet. With the dimensions changed, the product may retain the sameshape and its changes are often not listed. First, the members should check the changesin the particular component.

5) Note the changes, and discuss if there are any concerns other than those listed inthe worksheet.Next, envisage the environmental conditions under which the particular component is tobe used, then all members should think what concerns will result from the changes made(notice the changes made deliberately and those resulting from them), while puttingthemselves in the customers' shoes.It may be hard for a person to identify all concerns (failure modes) all alone in a shorttime. However, debate by all members from various angles should identify modes otherthan the items listed in the DRBFM worksheet. The DRBFM worksheet provides aseparate field in the field for concerns concerning the changes, where ideas raised in aDRBFM session can be entered. Entering such ideas in the separate field may identifythe items raised from angles different from those people are accustomed to and maylead to new ideas.

6) Note the changes. Discuss in what cases concerns will result and the causes offunctional disorders and unmarketability (failure modes).As described in the procedure for creative FMEA described above, the possibility oflisting up specific items about the causes of concerns (failure modes) is the key to usefuldiscussion in the subsequent "items to be reflected on the design," "items to be reflectedon the evaluation," and "items to be reflected on the manufacturing process." In aDRBFM session, have debate about each item listed in the worksheet and discuss anyother causes from various angles. The DRBFM worksheet provides a separate fieldsimilar to those for concerns, which can be stratified.Debate about the causes of concerns (failure modes) should be deepened until theparticipants come to envisage concretely a specific symptom of defect in their minds. Ifthe factors are too complicated for people to identify the causes, an FTA-assistedanalysis is recommended.If specific results can be obtained from a study of the causes of failures peculiar to theparticular part, each cause can be given a specific corrective action in debate about thesubsequent "items to be reflected on the design," "items to be reflected on theevaluation," and "items to be reflected on the manufacturing process."

7) Connect the factors about the manufacturing process FMEA.Variances in the manufacturing process should also be considered. If methods ofmaterial control and manufacturing conditions may affect component performance, havesufficient debate abut the factors related to the manufacturing process as well. If suchcannot be identified in DRBFM, they should be discussed in process FMEA.

(20/39)

8) Examine the design considerations implemented to eliminate the concerns.The DRBFM worksheet lists up the items already incorporated in the design, itemsfor which design examinations were conducted in advance, and other items for whichcorrective actions are possible, selected from among the design requirements,design standards, and checklists of trouble prevention concerning the causes of theconcerns identified with attention paid to the changes in the stage of designexamination.The DRBFM identifies the additional items and items that cannot be subjected tosolutions with traditional designs and evaluations alone, based on a discussion of theitems considered in the stage of design examination. Concerning the concerns thatare considered to be likely to be resolved by using a conventional design as a resultof the discussion, you can lower the priority ranking of the discussion. As a result, itshould become clear what the peculiar problems are in relation to the changes.

9) Discuss design actions and evaluation methods while examining the particularcomponent and its drawings carefully for each concern and its cause inrelation to the changes.While checking each cause listed in the DRBFM worksheet, discuss the designactions and evaluation methods for each item and identify the "items to be reflectedon the design (design actions)," "items to be reflected on the evaluation(considerations to be noted in the evaluation)," and "items to be reflected in themanufacturing process (such as process control items)."In discussions about strength, you are to check the method of calculating the safetyfactor and data to be used. Discussions about dimensional tolerances are designedto check the method of drawing instructions and process capability. On the otherhand, items where changes over time are an issue need to be tested. You are todiscuss and determine in concrete terms the temperature, time, and conditions ofdeterioration, and test method.At that time, it is important to proceed with debate while matching each item to eachcause, while looking closely at the particular component and its drawings in order toavoid collective debate about two or three items at one time. If debate covers aswide range of topics, fill in later items provisionally and then go back to the originalconcern (failure mode). It is important to determine the corrective actions discussed,on the spot. If any item can be dropped, specify it in the DRBFM worksheet. If youleave it for later, your homework will build up, making you stuck.While in debate about the concerns (failure modes) and their causes, you will havemany items. To organize such discussions, you will have to identify the items to beconsidered in the design, items to be checked in the evaluation, and items to be fedback to the manufacturing process. You will often see a case where the conclusion isthat all items will be checked in a durability test. Before checkup by durability testing,you must first make a "basically good design." You should also be able to omit a partof the evaluation process by using imaginative methods of design calculation anddrawing instructions.If variances in the manufacturing process or other manufacturing condition affectsthe performance of a specific component, have sufficient debate about the causesrelated to the process. In order to ensure a good performance of the component,identify the items to be considered and controlled for the manufacturing process andenter the items to be fed back to the manufacturing process, in the "items to bereflected in the manufacturing process." Use a DRBFM worksheet to have a closelinkage with the "process FMEA" and the manufacturing process to be implementedlater on.

(21/39)

The difference between the checklist and the DRBFM is that the checklist is"something t observe common requirements," while the DRBFM is "something thathelps find requirements peculiar to a specific design." In filling out the worksheet,therefore, do not use such comprehensive expressions as "as per the designstandards" and "perform various durability tests." Instead, use such specificexpressions as "the ......... region ensures a value R of 0.5" and "measure thedimensions of the sliding parts after the operation durability test."As you go on that far with the debate, you will have clarified the problems andcorrective actions peculiar to the component regarding the changes. However, sincewe have proceeded with the debate for each component, you may overlook theproblems that may arise on the borders between components. Sometimes note alsothe relationship between surrounding components and the relationship among thecomponents in the entire system by going back to the beginning, asking yourself"let's see if there is any other concerns."

Do these prior to the DRBFM. Discuss these in the DRBFM.

10) Specify a department responsible, person responsible, and deadline.Concerning the items discussed in terms of the corrective actions, specify the itemsto be reflected on the design, evaluation, and manufacturing, then determine aperson responsible and deadline.

Component

ChangeFunction

Concerns over the change

Loss of functionand

unmarketabilitydue to change

Any otherconcerns?(DRBFM) Fr

e-qu

ency

Concerns in what case?

Cause/factorAny otherfactors toconsider?(DRBFM)

Effects oncustomers

What design was made toeliminate the concerns?

(such as designrequirements, designstandards, and check

sheets)

Recommended actions (DRBFM results)

Items that the DRBFMindicates should be

reflected on thedesign

Activitiesperformedas a result

of theactions

Rep

rese

ntat

ive

Dea

dlin

e

Impo

rtanc

e

Prio

rity

ratin

g

Rep

rese

ntat

ive

Dea

dlin

e

Rep

rese

ntat

ive

Dea

dlin

eItems that the DRBFMindicates should be

reflected on theevaluation

Items that the DRBFMindicates should be

reflected on themanufacturing process

No.

11) Organize the discussions in the DRBFM and complete the FMEA.Discuss the concerns that are likely to occur as a result of a specific change(changes made and those resulting from them) in the DRBFM (failure modes) andtheir causes. Determine design actions, evaluation methods, and action methodsand organize the items in the form of "items to be reflected on the design (designactions)," "items to be reflected on the evaluation (considerations to be noted in theevaluation)," and "items to be reflected on the manufacturing (items to be reflectedon the process)." You can then complete the FMEA.

Component

ChangeFunction

Concerns over the change

Loss of functionand

unmarketabilitydue to change

Any otherconcerns?(DRBFM) Fr

e-qu

ency

Concerns in what case?

Cause/factorAny otherfactors toconsider?(DRBFM)

Effects oncustomers

What design was made toeliminate the concerns?

(such as designrequirements, designstandards, and check

sheets)

Recommended actions (DRBFM results)

Items that the DRBFMindicates should be

reflected on thedesign

Activitiesperformedas a result

of theactions

Rep

rese

ntat

ive

Dea

dlin

e

Impo

rtanc

e

Prio

rity

ratin

g

Rep

rese

ntat

ive

Dea

dlin

e

Rep

rese

ntat

ive

Dea

dlin

eItems that the DRBFMindicates should be

reflected on theevaluation

Items that the DRBFMindicates should be

reflected on themanufacturing process

No.

(22/39)

12) Check if the items discussed in the DRBFM are actually reflected on the drawingsand evaluation items and effectively "prevent failures."We believe it important for a DRBFM worksheet, which is as it were a crystallization ofwisdom with much work, is used in relation to all processes ranging from design(drawings) to evaluation and then to quality auditing. These days, many developedcomponents are based on FMEA. However, it is far from true that a checkup isconducted to see if the worksheets are maintained in the process of development andthe items discussed in the DRBFM are actually reflected on the drawings and evaluationitems. The completion of a worksheet does not mean that of DRBFM. To make DRBFMdebate prove effective, always follow up on the items listed below, check the actions,and write the results down in the field for "activities taken as a result of the actions."

13) DRBFM on the test-completed productIn the DRBFM conducted in the drawing stage, we identified predictable concerns anddetermined specific actions to be taken. Concerning action methods discussed in the"items to be reflected on the design," be sure to conduct the DRBFM on the test-completed product when the prototype incorporated in the drawings is complete and theevaluation designed to check its effect is complete.Disassemble each component and conduct the DRBFM while watching the drawings andthe DRBFM worksheet. To check the changes in the internal structure of the particularcomponent, provide a sample with a cut cross section and check every corner of theinside sufficiently.

Cut and see.Disassemble and see.

Drawing

FMEA　　　　　　　　　　　　Work　　　　Sheet

a) Check if the items listed in "items to be reflected on the design" are reflected on thedrawings of the component.

b) Check if the items listed in "items to be reflected on the evaluation" are reflected onthe evaluation items and evaluation conditions and an actual evaluation conducted.

c) Check if the items listed in "items to be reflected on the manufacturing process" arereflected on the control and inspection items of the manufacturing process.

(23/39)

Similarly to the DRBFM conducted in the stage of drawing, note the changes and checkfor "any other concerns" and "any other factors" while monitoring the test results andchecking the entries made in the "items to be reflected on the evaluation" in theworksheet. At that time, it is important not only to discuss whether the answer is yes orno. It is also very important to hold each test-complete component in your hands andhave a close look at it. To find hidden issues such as "is this test appropriate?" and "isit not necessary to redesign the product in view of the condition of the component?"Conduct a sufficient analysis of the "looks" of the test-complete product.When having a close look at the "looks" of a discolored or scratched product, thecomponent you are looking at should begin talking to you about the hidden issues. It isimportant to examine each corner of the product well until you have such a feeling.(Note: See Section 5-3 "What you should be ready for in the DRBFM: [What you shouldbe ready for when looking at a commodity].)

14) DRBFM in the manufacturing processThe DRBFM in the manufacturing process can be conducted in the same manner as inthe drawing stage. Instead of the component, note the changes in each process,identify the concerns anticipated and their causes, and determine specific actionmethods. You are also to determine specific action methods to eliminate problemsrelated to the manufacturing process discussed in the DRBFM of the drawing stage.In debate about specific action methods, it is important to stratify and organize theitems to be implemented in the process design and the items to be implemented in theprocess control. Take care not to lead the personnel responsible to the conclusion thatall actions are to be taken by process control and inspection.

We have so far discussed the steps for implementing the DRBFM. Although the FMEAmay look inaccessible at first, you can complete it progressively by conducting theDRBFM (that is, combining it with a design review and letting many interestedengineers share their ideas).We earnestly recommend you to use the FMEA method on a product you are currentlydeveloping, as at ease as if you were writing meeting minutes, and try a creative designreview: Design Review Based on Failure Mode (DRBFM).

Component

Change

Function

Concerns over the change

Loss of functionand

unmarketabilitydue to change

Any otherconcerns?(DRBFM) Fr

e-qu

ency

Concerns in what case?

Cause/factorAny otherfactors toconsider?(DRBFM)

Effects oncustomers

What design was made toeliminate the concerns?

(such as designrequirements, designstandards, and check

sheets)

Recommended actions (DRBFM results)

Items that the DRBFMindicates should be

reflected on thedesignIm

porta

nce

Prio

rity

ratin

g

Rep

rese

nta-

tive

Dea

dlin

eItems that the DRBFMindicates should be

reflected on theevaluation

No.

Rep

rese

nta-

tive

Dea

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e

Activitiesperformedas a result

of theactions

Wax theinside ofthe door.Frommanual toautomaticwaxing

1 Wax thebottom oftheinside ofthe door.

Insufficientwaxing insomeareas

Spray head clogged up1)Wax viscosity too highDischarge pressure too lowWax too cold

---

Reducedcorrosionresistanceof the door

Use a coatingspray gun.

-1)

2)

Add an automatictemperatureregulator and anautomatic agitator tothe wax tank.Add a check processto the spray pattern.

1)

2)

Control wax viscositythoroughly (twice,directly).Clean the spray headmore frequently(twice, directly).

(24/39)

Section 6. An embodiment: Hair drier

Photo 2. An exploded-view photo of a hair drier

As an actual embodiment, let's pick up the hair drier. It involves 58 components as shownin Table 1, while Photo 2 shows the shapes of the main components.The hair drier is based on the following specifications:- Power supply: 100V AC, 50/60Hz - Power consumption: 1,200W for hot air- Hot air temperature: 120°C (ambient temperature, 30°C)- Weight: 34g - Cord length: 1.8m- Equipped with a overheat controller (thermostat and temperature fuse)

Fig. 8. General view of the hair drier Fig. 9. Overheat controller

16 13 14-2 14-125

23

3

50 51

4

62

17

18

1967

15

Fig. 10. Electric circuit diagram

Bimetal (30) Traveling contact plate (29)

Terminal block (32) Terminal block (33)

(25/39)

Contact (28)

Insulation block (31)

To reach the component being discussed, disassemble it to the constituent for which apart diagram is available. The point in disassembling the product to the constituents is inthe possibility of consideration while having a close look at the drawings and component.You can concentrate on the target component by considering each constituent.

The target component of the hair drier picked up for the present case study consists of 58constituents shown in Table 1. If it is better to consider the product on a unit-by-unit basiswith the parts collected in small groups, enter a unit designation in the field for the targetcomponent.

Fig. 11. Structure diagram of a typical DC motor

Bearing (42) Commutator (39) Rotor (69) Ferrite (40) Housing (70) End plate (71)

Brush (38)

(26/39)

Table 1. Composition of a typical hair drier (a hierarchical structure)

Power supply

Casing

Heat source

Fan

Connection unit

Cord U (61)(unit) Plug (1)

Power cord (2)Protector (3)

Switch UControl lever (4)

Switch proper (62)

Contact (5)Contact spring (6)Traveling contact (7)Contact grease (8)Slider (9)Slider click (10)Switch cover (11)Switch base (12)

Temperature fuse

Body U

Grip U

Heat-insulatingU (63)

Heater U (64)

Heater holderU (65)

Overheatcontroller U (66)

Body A (13)

Body B-2 (14-2)Barrier (15)Hood (16)

Grip A (17)Grip B (18)Hinge ring (19)Tapping (20)

Heat-insulating mica (21)

Heat-insulating plate (22)

Heater A (23)Heater B(24)Mica A (25)Mica B (26)Clamp (27)Contact (28)Traveling contact plate (29)Bimetal (30)Insulating block (31)Terminal A (32)Terminal B (33)

Motor U

Fan U

DC motor (67)

Rotor (69)

Rectificationmechanism

Shaft (34)Core (35)Windings (36)Commutator (39)Brush (38)Brush holder (39)

Ferrite (40)Housing (70) Case (41)

Bearing A (42)Bearing B (43)

End plate (71) Terminal (44)Terminal holder (45)Sealing mica (46)

Voltage-dropresistance (47)Ripple capacitor (48)Diode (49)

Motor holder (50)Fan (51)

Electricconnection U (68)

Lead (52)Lead wire (53)Terminal lug (54)Crimp terminal (55)Insulating tube (56)Soldering (57)Stopper (58)

Manual UOperating manualPrecaution labelTag

Hai

r drie

r

Body B-1 (14-1)

(27/39)

Photo 5. An exploded-view photo of the motor, motor holder, and fan

Photo 4. Motor holder Photo 3. An exploded-view photo of the bodies B-1 and B-2

When all constituents are listed up, identify the target constituents, for both the changes madedeliberately and those resulting from them.In the present discussion, we will assume that the operating environmental conditions are thesame as those of conventional hair driers and will explain how to disassemble the hair drier,while noting only the changes made deliberately. For the changes made deliberately, make asufficient check on the changes in material, material changes, and changes in shapes (such aschanges in plate thickness and dimensions). For constituents that remain completelyunchanged and based on traditional designs without modification, you can lower the priorityranking in the FMEA. First, note the components subjected to a change and proceed with theconsideration.In this study, we base ourselves on the assumption that design changes have been madeconcerning the three components listed below. Fig. 14 shows typical entries made in theDRBFM worksheet.

Snap fit Screw tightening hole

Press-fit the fan directly.

14－－－－2

14－－－－1

50505050

Lug A

Orifice BNote: Snap fitThe flexibility of the resinmaterial is used to build astructure where the lug A isinserted into the orifice Band the lug A is stuck, thusbeing prevented fromcoming loose.

① Simplifying the mating methods for the parts of the casing and the "rear bodies (14-1 and14-2)":Switch from snap-fit mating (see Photo 3) to a friction melting structure (where the resin ismelted with friction heat from vibration).

② Change the method of fixing the motor holder (50) and motor from screw fastening to directpress-fitting.

(28/39)

　　　　　　　　　　　　

　　　　　　　　　　　　　　　　　

Listed below are the operating conditions for a typical hair drier in view of the need todry hair, wet laundry, and futon.

You are to secure such operating conditions first, then proceed with your FMEA.Some customers may be using the product in a peculiar manner. Although it may seemodd to the designers, the customers may find it quite an ordinary method of use. Thedesigners should therefore give sufficient consideration at this stage.

- Operating atmospheric temperature: -10 to 35°C- Operating humidity: 95% (possibility of use with a wet hand)- Applicable regions: Throughout the country (from excessively salty sea coasts to

cold areas)- Applicable places: Bathrooms, lavatories, kitchens, living rooms- Storage: Lavatories (hot and humid), living rooms (directly sunlit, hot)- Users: From children to adults- Power supply: Service outlet (possibly with too many cords plugged into a single

service outlet)- Operation time: Normal (approx. 10 minutes), continued use (negligence to switch

off the unit)- Objects to be dried: Drying of hair and wet clothes and futon, as well as softening

of resins and adhesives, among other objectives- Abnormal use: Purposes other than drying (such uses as children's toys and fans)- Other: Possibility of disassembly when broken down

(29/39)

Concerning the hair drier that we picked up for the present case study, we will note thechanges in the three components listed below and identify the concerns to be anticipated asa result of such redesigns, by taking full advantage of our creativity.

（14－1）（14－2）

(Motor )

1.5

Motor holder（50）

Screw fastening

Before thechange

t

① Simplifying the method of mating the parts of the casing and the "rear bodies (14-1) and(14-2)":Change from snap fit mating to a friction melting structure. Fig. 12 shows a structuraloutline of the fused parts.

Fig. 12. A structural outline of the fused parts of the rear bodies

Fig. 13. A structural outline of the location where the motor holder is press-fitted

After thechange

Extension

② Change the method of fastening the motor holder (50) and the motor from screwfastening to direct press-fitting to prevent them from coming loose. Fig. 13 shows astructural outline of the press-fit parts.

If there is no change whatsoever in the designs of other constituents shown in Table 1,you have only to proceed with your FMEA for the changed parts alone. However, youmust examine carefully what the changes are. (Note the changes made deliberately andthose resulting from them.)In the present study, we are to proceed with the embodiment concerning the changes inthe friction fusion structure of the mating parts of the "rear bodies (14-1) and (14-2)" of①. While referring to the case ①, conduct the DRBFM starting with the FMEA, inrelation to the case where the method of fastening the motor holder (50) in ② and themotor from screw fastening to direct press-fitting in order to prevent them from comingoff. Shown below is the press-fitting process implemented as a result of the study of themotor holder dimensions, the characteristics of the resin materials of the holder, and therequired press-fit load when direct-fitting is used.

(30/39)

(31/39)

【【【【Characteristics of polypropylene resin: at normal temperature】】】】1) Vertical plastic modulus (E): 1000MPa 2) Tensile strength : 30MPa3) Coefficient of linear expansion : 11～12×10-5/°C

(Coefficient of linear expansion of the motor casing); 1×10-5/°C)

【【【【Study overview of the dimensions of the press-fit parts and the press-fit load 】】】】

Stress in the directionof compression σr

E・δ・(R32－ R2

2)

2・R2・R32

P・(R32＋ R2

2)

R32 － R2

2

δ: Compression margin of the motor holder

1) Maximum stress in thedirection of compression σr

max

E・δmax・(152－ 13.62)

2×152×13.6= 0.13 kg/mm2

2) Maximum stress in the directionof circumference σt

maxσr

max×(152 + 13.62)

152－13.62= 1.34 kg/mm2

3) Required press-fit load P = σrmax・S・μ = 0.13×(27.2・π×17.4）×0.2

= 0.13×1486×0.2 = 38.6kg

(Assume that the PP motor holder and the motor circumference have a friction coefficient (µ) of 0.2.)

【【【【Overview of the press-fit process (Press-fit the motor holder, then solder thewire harness.) 】】】】

Fasten the motor casing. Install the motor holder. Press-fit the motor holder.

P

Motor holder OD : 2R3=30.0Motor holder ID : 2R2=27.3±0.1Motor OD : 2R1=27.6

―　 Dimensions of the motor holder 　―

（δmax＝0.2mm）

=

Stress in the directionof circumference σt

=

=

=

(32/39)

Concerning the hair drier we picked up for the present case study, note the changes in thetwo components in the case 1), then identify the concerns to be anticipated as a result ofsuch redesigns, by taking full advantage of your creativity as an FMEA implementer.

First of all, enter the rear bodies (14-1) and (14-2) (to be subjected to the FMEA) in the fieldfor the component designations. Then specify the friction fusion structure to be changed.Concerning the functions of the components, do not forget to list up the relationships withthe surrounding parts and the functions of the components in terms of marketability.

If no change whatsoever has been made in the designs of other components shown inTable 1, you have only to proceed with your FMEA for the changed parts alone. However,the FMEA implementer is requested to identify the changes (changes made deliberately andthose resulting from them) carefully.

Fig. 14. FMEA worksheet for a typical hair drier (1)

DRBFM WORK SHEET (For new designs and redesigns )Design Review Based on Failure Mode

① Simplifying the method of mating the parts of the casing and the "rear bodies (14-1 and14-2)":Change from snap-fit mating to a friction fusion structure.

(33/39)

No.

Component

ChangeFunction

Concerns over the change

Loss of functionand

unmarketabilitydue to change

Any otherconcerns?(DRBFM)

Concerns in what case?

Cause/factor

Any otherfactors toconsider?(DRBFM)

Effects oncustomers

What design was made toeliminate the concerns?

(such as designrequirements, designstandards, and check

sheets)

Recommended actions (DRBFM results)

Items that the DRBFMindicates should be

reflected on thedesign

Activitiesperformed asa result of the

actions

Model ;System ;Component; Originator; DR members;

No.;Date prepared;Date corrected;

Rep

rese

ntat

ive

Dea

dlin

e

Impo

rtanc

e

Prio

rity

ratin

g

Rep

rese

ntat

ive

Dea

dlin

e

Rep

rese

ntat

ive

Dea

dlin

eItems that the DRBFMindicates should be

reflected on theevaluation

Items that the DRBFMindicates should be

reflected on themanufacturing process

Body B-1(14-1)

1

Frictionfusionstructure

Body B-2(14-2)

2

Frictionfusionstructure

1. Fasteningthe bodyB-2

2. Preventingtheingress offoreignmatter

3. Air intake

1. Holdingthe body A

2. Holdingthe bodyB-1

3. Holdingthe grip U

4. Smoothactivationof the gripU

Fre-

quen

cy

Concerning the hair drier we picked up in the present case study, we noted the change 1)and summed up the designations of the components to be studied and their changes, alongwith their functions in Fig. 14.

Next, you are to identify the concerns to be anticipated as a result of the redesigns asdescribed in ①, by taking full advantage of your creativity as an FMEA implementer. Here,you must list up all concerns anticipated. Since they can be discussed in the latter half ofthe DRBFM, it is so designed that the items identified in the DRBFM can be entered in thefield for "Any other concerns? (DRBFM)."

Fig. 15. FMEA worksheet for a typical hair drier (2)

(34/39)

① Simplifying the method of mating the parts of the casing and the "rear bodies B-1 (14-1)and B-2 (14-2)":Change from snap fit mating to a friction fusion structure.

DRBFM WORK SHEET (For new designs and redesigns )Design Review Based on Failure Mode

No.

Component

ChangeFunction

Concerns over the change

Loss of functionand

unmarketabilitydue to change

Any otherconcerns?(DRBFM)

Concerns in what case?

Cause/factor

Any otherfactors toconsider?(DRBFM)

Effects oncustomers

What design was made toeliminate the concerns?

(such as designrequirements, designstandards, and check

sheets)

Recommended actions (DR BFM results)

Items that the DRBFMindicates should be

reflected on thedesign

Model ;System ;Component; Originator; DR members;

No.;Date prepared;Date corrected;

Rep

rese

ntat

ive

Dea

dlin

e

Impo

rtanc

e

Prio

rity

ratin

g

Rep

rese

ntat

ive

Dea

dlin

e

Rep

rese

ntat

ive

Dea

dlin

eItems that the DRBFMindicates should be

reflected on theevaluation

Items that the DRBFMindicates should be

reflected on themanufacturing processFr

e-qu

ency

Body B-1(14-1)

1

Frictionfusionstructure

Body B-2(14-2)

2

Frictionfusionstructure

1. Fasteningthe bodyB-2

1. Holdingof thebody B-1

1. Looseningdue to acrack in theresin of themating parts

2. Enlargeddistortion ofthe resin ofthe matingparts

3. A leveldifference inthe matingparts (lowmarketability)

4. Fusion burrsin the matingparts (lowmarketability)

1. Looseningdue to acrack in theresin of themating parts

2. Enlargeddistortion ofthe resin ofthe matingparts

3. A leveldifference inthe matingparts (lowmarketability)

4. Fusion burrsin the matingparts (lowmarketability)

Activitiesperformed asa result of the

actions

We have listed up in Fig. 15 the results of a study of the concerns to be anticipated as aresult of the redesign as described in ①. Next, consider in concrete terms how theconcerns over the changes will occur.

Fig. 16 shows a typical result of a study of the ways and causes of concerns over thechanges occurring, concerning the body B-1 (14-1). Here, you should list up allconceivable causes. Since you can consider them again in the latter half of the DRBFM, itis so designed that the items identified in the discussion in the DRBFM can be enteredinto the field for "Any other factors to be considered? (DRBFM)."

Fig. 16. FMEA worksheet for a typical hair drier (3)

(35/39)

Component

ChangeFunction

Concerns over the change

Loss of functionand

unmarketabilitydue to change

Any otherconcerns?(DRBFM) Fr

e-qu

ency

Concerns in what case?

Cause/factorAny otherfactors toconsider?(DRBFM)

Effects oncustomers

What design was made toeliminate the concerns?

(such as designrequirements, designstandards, and check

sheets)

Recommended actions (DR BFM results)

Items that the DRBFMindicates should be

reflected on thedesign

Activitiesperformedas a result

of theactions

Rep

rese

ntat

ive

Dea

dlin

e

Impo

rtanc

e

Prio

rity

ratin

g

Rep

rese

ntat

ive

Dea

dlin

e

Rep

rese

ntat

ive

Dea

dlin

eItems that the DRBFMindicates should be

reflected on theevaluation

Items that the DRBFMindicates should be

reflected on themanufacturing process

No.

DRBFM WORK SHEET (For new designs and redesigns )Design Review Based on Failure ModeModel ;

System ;Component; Originator; DR members;

No.;Date prepared;Date corrected;

Body B-1(14-1)

1

Frictionfusionstructure

Fasteningthe bodyB-2

2.

1. Looseningdue to acrack in theresin of themating parts

2. Enlargeddistortion ofthe resin ofthe matingparts

3. A leveldifference inthe matingparts (lowmarketability)

4. Fusion burrsin the matingparts (lowmarketability)

1. Looseningdue to acrack in theresin of themating parts

1.

2.

3.

4.

5.

6.

The fused parts break downdue to thermal deterioration.The resin in the fused partscracks due to creepdistortion.The mating parts undergofusion damage due to heat.The mating parts breakdown due to motor vibration(microscopic vibration orresonance).The fused parts getdamaged due to therepetition of thermalexpansion and shrinkage.The fused parts break downdu to a drop impact imposedwhen assembled or in use.

1.

2.

3.

4.

The poorly fused parts getdistorted greatly due to heat.The fused parts getdistorted due to moisture.The body gets distorted dueto residual strains occurringat the time of molding.Poor fusion results inreduced penetration,leading to great distortion.

1.

2.

3.

The bodies get distorted dueto residual strains occurringat the time of molding,resulting in a level difference.The poorly fused parts getdistorted due to heat,resulting in a level difference.A level difference occurs dueto a phase deviation at thetime of fusion.

1.

2.

Excessive penetration in thefused parts results in stuck-out burrs.A large gap between themating parts results in stuck-out burrs.

Fig. 15 summarizes the study results of what concerns are anticipated as a result of theredesign as presented in ①, while Fig. 16 lists up the items that may cause suchsymptoms.The next step is to specify in concrete terms what designs have been made to eliminatethe adverse effects on the customers and the concerns related to the particular change, inrelation to the causes of the concerns.In the stage where the FMEA is implemented, the design of the body B-1 (14-1) should bealmost complete. Fill out the worksheet while basing yourself on the design requirements,design standards, and defectives-preventive checklists, along with other information andwhile relating them with the items already incorporated in the design at that time and theitems subjected to design consideration in advance, and other adverse factors andcauses to be anticipated.

Fig. 17. FMEA worksheet for a typical hair drier (4)

A

B

B

(36/39)

Component

ChangeFunction

Concerns over the change

Loss of functionand

unmarketabilitydue to change

Any otherconcerns?(DRBFM) Fr

e-qu

ency

Concerns in what case?

Cause/factorAny otherfactors toconsider?(DRBFM)

Effects oncustomers

What design was made toeliminate the concerns?

(such as designrequirements, designstandards, and check

sheets)

Recommended actions (DR BFM results)

Items that the DRBFMindicates should be

reflected on thedesign

Activitiesperformedas a result

of theactions

Rep

rese

ntat

ive

Dea

dlin

e

Impo

rtanc

e

Prio

rity

ratin

g

Rep

rese

ntat

ive

Dea

dlin

e

Rep

rese

ntat

ive

Dea

dlin

eItems that the DRBFMindicates should be

reflected on theevaluation

Items that the DRBFMindicates should be

reflected on themanufacturing process

DRBFM WORK SHEET (For new designs and redesigns )Design Review Based on Failure ModeModel ;

System ;Component; Originator; DR members;

No.;Date prepared;Date corrected;

No.

Body B-1(14-1)

1

Frictionfusionstructure

Fasteningthe bodyB-2

2. Enlargeddistortion ofthe resin ofthe matingparts

3. A leveldifference inthe matingparts (lowmarketability)

4. Fusion burrsin the matingparts (lowmarketability)

1. Looseningdue to acrack in theresin of themating parts

1.

2.

3.

4.

5.

6.

The fused parts break downdue to thermal deterioration.The resin in the fused partscracks due to creepdistortion.The mating parts undergofusion damage due to heat.The mating parts breakdown due to motor vibration(microscopic vibration orresonance).The fused parts getdamaged due to therepetition of thermalexpansion and shrinkage.The fused parts break downdu to a drop impact imposedwhen assembled or in use.

1.

2.

3.

4.

The poorly fused parts getdistorted greatly due to heat.The fused parts getdistorted due to moisture.The body gets distorted dueto residual strains occurringat the time of molding.Poor fusion results inreduced penetration,leading to great distortion.

1.

2.

3.

The bodies get distorted dueto residual strains occurringat the time of molding,resulting in a level difference.The poorly fused parts getdistorted due to heat,resulting in a level difference.A level difference occurs dueto a phase deviation at thetime of fusion.

1.

2.

Excessive penetration in thefused parts results in stuck-out burrs.A large gap between themating parts results in stuck-out burrs.

2.A

Low

Med

ium

Hig

hH

igh

Unserviceable(they find itrisky)

They find itdefective.

Unserviceable(they find itrisky)

They find itlow in quality.

1.

2.

3.

4.

Dimensions andshapes that resultin the breakdownof the basematerial in thegeneral part of theresinKeep it at or belowthe resin meltingtemperature withan overheatcontroller (at nomore than 120ºC).Unify the bodyproper at the samegrade for provenPP resins.Do not usecomponents thatdropped duringassembly.(Conduct thoroughprocess control.)

1.

2.

Determine theoptimal value byadjusting the fusionand moldingconditions.Unify the bodyproper with highlywater-resistant andproven PP resins.

1.

2.

Determine theoptimal value byadjusting thefusion and moldingconditions.Identify andimplementthoroughly theitems of processcontrol andinspection in thefusion process.

1.

2.

Determine theoptimal value byadjusting thefusion and moldingconditions.Identify andimplementthoroughly theitems of processcontrol andinspection in thefusion process.

The DRBFM allows the participants to have thorough debate on the items listed in theFMEA worksheets in Figs. 15 through 17 implemented so far by a single person fromdifferent angles, thus enabling you to find new items that you have never thought of before.Here, as typical items identified anew, we have entered the mode of "the smoking and burnsof the resin due to heat in the body B-1" in the field for "Any other concerns? (DRBFM)," andthe "progress in the cracks starting with the welds" and the "deterioration and cracks due tothe UV rays in direct sunlight" in the field for "Any other factors to be considered?(DRBFM)."

Fig. 18. FMEA worksheet for a typical hair drier (5)

A

A

B

B

7. Loosening due toprogress in the cracksstarting with the welds

8. Deterioration andcracks due to the UVrays in direct sunlight

5. Smoking andburns of the resindue to heat

DRBFM additions

DRBFM additions

(37/39)

DRBFM WORK SHEET (For new designs and redesigns )Design Review Based on Failure ModeModel ;

System ;Component; Originator; DR members;

No.;Date prepared;Date corrected;

Component

ChangeFunction

Concerns over the change

Loss of functionand

unmarketabilitydue to change

Any otherconcerns?(DRBFM) Fr

e-qu

ency

Concerns in what case?

Cause/factorAny otherfactors toconsider?(DRBFM)

Effects oncustomers

What design was made toeliminate the concerns?

(such as designrequirements, designstandards, and check

sheets)

Recommended actions (DR BFM results)

Items that the DRBFMindicates should be

reflected on thedesign

Activitiesperformedas a result

of theactions

Rep

rese

ntat

ive

Dea

dlin

e

Impo

rtanc

e

Prio

rity

ratin

g

Rep

rese

ntat

ive

Dea

dlin

e

Rep

rese

ntat

ive

Dea

dlin

eItems that theDRBFM indicates

should be reflectedon the evaluation

Items that the DRBFMindicates should be

reflected on themanufacturing process

No.

Body B-1(14-1)

1

Frictionfusionstructure

Fasteningthe bodyB-2

2. Enlargeddistortion ofthe resin ofthe matingparts

3. A leveldifference inthe matingparts (lowmarketability)

4. Fusion burrsin the matingparts (lowmarketability)

1. Looseningdue to acrack in theresin of themating parts

1.

2.

3.

4.

5.

6.

The fused parts break downdue to thermal deterioration.The resin in the fused partscracks due to creep distortion.The mating parts undergofusion damage due to heat.The mating parts break downdue to motor vibration(microscopic vibration orresonance).The fused parts get damageddue to the repetition of thermalexpansion and shrinkage.The fused parts break downdu to a drop impact imposedwhen assembled or in use.

1.

2.

3.

4.

The poorly fused parts getdistorted greatly due to heat.The fused parts getdistorted due to moisture.The body gets distorted dueto residual strains occurringat the time of molding.Poor fusion results inreduced penetration,leading to great distortion.

1.

2.

3.

The bodies get distorted dueto residual strains occurringat the time of molding,resulting in a level difference.The poorly fused parts getdistorted due to heat,resulting in a level difference.A level difference occurs dueto a phase deviation at thetime of fusion.

1.

2.

Excessive penetration in thefused parts results in stuck-out burrs.A large gap between themating parts results in stuck-out burrs.

1.

Med

ium

Hig

hH

igh

Unserviceable(they find itrisky)

They find itdefective.

Unserviceable(they find itrisky)

They find itlow in quality.

1.

2.

3.

4.

Dimensions andshapes that result inthe breakdown ofthe base material inthe general part ofthe resinKeep it at or belowthe resin meltingtemperature with anoverheat controller(at no more than120ºC).Unify the bodyproper at the samegrade for proven PPresins.Do not usecomponents thatdropped duringassembly. (Conductthorough processcontrol.)

1.

2.

Determine theoptimal value byadjusting the fusionand moldingconditions.Unify the bodyproper with highlywater-resistant andproven PP resins.

1.

2.

Determine theoptimal value byadjusting thefusion and moldingconditions.Identify andimplementthoroughly theitems of processcontrol andinspection in thefusion process.

1.

2.

Determine theoptimal value byadjusting thefusion and moldingconditions.Identify andimplementthoroughly theitems of processcontrol andinspection in thefusion process.

Low

While confirming the causes listed in the worksheet, discuss ways to make designs andevaluate them for each item and identify the "items to be reflected on the design (designactions)," "items to be designed on the evaluation (considerations to be noted in theevaluation)," and "items to be reflected on the manufacturing process (process control andinspection items)."

Fig. 19. FMEA worksheet for a typical hair drier (6)

A

A

(38/39)

DRBFM WORK SHEET (For new designs and redesigns )Design Review Based on Failure ModeModel ;

System ;Component; Originator; DR members;

No.;Date prepared;Date corrected;

Component

ChangeFunction

Concerns over the change

Loss of functionand

unmarketabilitydue to change

Any otherconcerns?(DRBFM)

Concerns in what case?

Cause/factorAny otherfactors toconsider?(DRBFM)

Effects oncustomers

What design was made toeliminate the concerns?

(such as designrequirements, designstandards, and check

sheets)

Recommended actions (DR BFM results)

Items that the DRBFMindicates should be

reflected on thedesign

Activitiesperformedas a result

of theactions

Rep

rese

ntat

ive

Dea

dlin

e

Impo

rtanc

e

Prio

rity

ratin

g

Rep

rese

ntat

ive

Dea

dlin

e

Rep

rese

ntat

ive

Dea

dlin

eItems that theDRBFM indicates

should be reflectedon the evaluation

Items that the DRBFMindicates should be

reflected on themanufacturing process

No.

Fre-

quen

cy

Body B-1(14-1)

1

Frictionfusionstructure

Fasteningthe bodyB-2

2. Enlargeddistortion ofthe resin ofthe matingparts

1. Looseningdue to acrack in theresin of themating parts

The fused parts break downdue to thermal deterioration.

The poorly fused parts getdistorted greatly due to heat.

Med

ium

Unserviceable(they find itrisky)

Unserviceable(they find itrisky)

1. Dimensions andshapes that resultin the breakdownof the basematerial in thegeneral part of theresin

1. Determine theoptimal value byadjusting thefusion andmoldingconditions.

Low1.

1.

The resin in the fused partscracks due to creep distortion.

2.

The mating parts undergofusion damage due to heat.

3.

The mating parts break downdue to motor vibration(microscopic vibration orresonance).

4.

The fused parts get damageddue to the repetition of thermalexpansion and shrinkage.

5.

The fused parts break downdu to a drop impact imposedwhen assembled or in use.

6.

Loosening due to progress inthe cracks starting with thewelds

7.

Deterioration and cracks dueto the UV rays in directsunlight

8.

1.

The fused parts getdistorted due to moisture.

2.

The body gets distorted dueto residual strains occurringat the time of molding.

3.

Poor fusion results inreduced penetration,leading to great distortion.

4.

2. Unify the bodyproper with highlywater-resistantand proven PPresins.

2. Keep it at or belowthe resin meltingtemperature withan overheatcontroller (at nomore than 120ºC).

3. Unify the bodyproper at the samegrade for provenPP resins.

4. Do not usecomponents thatdropped duringassembly.(Conduct thoroughprocess control.)

Consider the fusionconditions (frequency,time, and pressureapplied) under whichthe base metal breaksdown in the generalpart.

Shape the fused partswith a level differenceand provide aclearance of 0.2mm tocontain the burrs.

*

*

Subject a samplewith the worstfusion conditionsto heatdeterioration, thenperform a staticstrength test.(80°C × 2,000 hrs)

*

Subject a sample with theworst fusion conditions tothermal deterioration, thenperform a distortion test.(80°C × 2,000 hrs)

*

Check the PP resinsfor distortiontemperature andfusion startingtemperature.

*

Subject a sample withthe worst fusionconditions to thermaldeterioration, thenperform a vibrationdurability test.(80°C × 2,000 hrs)

*

Subject a samplewith the worst fusionconditions to a coldand heat repeat test.(-20°C to 120°C ×100 cycle)

*

Perform a low-temperature (-20°C)drop test (1.5m) onnew samples andthermallydeteriorated ones(80°C x 2,000 hrs).

* Prevent it fromdropping duringassembly and strictlyprohibit the use ofdroppedcomponents.

*

Subject a sample withthe worst moldingconditions to thermaldeterioration, thenperform a vibrationdurability test.(80°C x 2,000 hrs)

* Control the moldingconditions (moldtemperature andinjection pressure).

Consider a multi-point gate, film gate,and otherparameters for amold structure.

*

Weatherproofness(Sun Shine) (If thecurrent PP isproblem-free, use aproduct of the samegrade.)

*

*

Control the fusionconditions(frequency, time,and pressureapplied).

Consider the fusionconditions (frequency,time, and pressureapplied) under whichthe base materialbreaks down in thegeneral parts.

Subject a sample withthe worst fusionconditions to thermaldeterioration, thenperform a distortiontest.(80°C × 2,000 hrs)

* Subject a sample withthe worst fusionconditions to a cold,humid, and heatrepeat test. (-20°C to50°C, 90% to 120% ×100 cycle)

Subject a sample withthe worst fusionconditions to thermaldeterioration, thenperform a distortiontest.(80°C × 2,000 hrs)

If residual strains afterthe molding are great,consider usingannealing (thermaltreatment).

Control the moldingconditions (moldtemperature andinjection pressure).

* Consider the fusionconditions (frequency,time, and pressureapplied) under whichthe base metal breaksdown in the generalparts.

*

*

Check the penetrationstatus of the crosssection of the fusedparts by a polarizationmicroscope.Perform a staticstrength test on asample with the fusionconditions.

Control the fusionconditions(frequency, time,and pressureapplied).

*

* * *

* * *

In the final step, you should follow up on whether the items determined in the DRBFM areactually reflected on the drawings and evaluation items. Enter the follow-up results into thefield for "activities as a result of the actions" in the worksheet.After the DRBFM, it is important to use the worksheets while maintaining the additions andcorrections and constantly checking that the decisions are actually implemented.

Fig. 20. FMEA worksheet for a typical hair drier (7)

A

A

A

B

C

B

A

A

C

C

A

A

C

A

00/02

00/03

99/11

00/02

00/04

00/02

00/03

00/04

99/12

00/03

99/03

00/03

00/03

00/04

00/03

00/04

00/02

(39/39)

DRBFM WORK SHEET (For new designs and redesigns )Design Review Based on Failure ModeModel ;

System ;Component; Originator; DR members;

No.;Date prepared;Date corrected;

Component

ChangeFunction

Concerns over the change

Loss of functionand

unmarketabilitydue to change

Any otherconcerns?(DRBFM)

Concerns in what case?

Cause/factorAny otherfactors toconsider?(DRBFM)

Effects oncustomers

What design was made toeliminate the concerns?

(such as designrequirements, designstandards, and check

sheets)

Recommended actions (DR BFM results)

Items that the DRBFMindicates should be

reflected on thedesign

Activitiesperformedas a result

of theactions

Rep

rese

ntat

ive

Dea

dlin

e

Impo

rtanc

e

Prio

rity

ratin

g

Rep

rese

ntat

ive

Dea

dlin

e

Rep

rese

ntat

ive

Dea

dlin

eItems that theDRBFM indicates

should be reflectedon the evaluation

Items that the DRBFMindicates should be

reflected on themanufacturing process

No.

Fre-

quen

cy

Body B-1(14-1)

1

Frictionfusionstructure

Fasteningthe bodyB-2

2. Enlarged distortionof the resin of themating parts

1. Loosening due to acrack in the resin ofthe mating parts

1. The fused parts break downdue to thermal deterioration.

The poorly fused parts getdistorted greatly due to heat.

Med

ium

Low

1.

The resin in the fused partscracks due to creep distortion.

2.

The mating parts undergofusion damage due to heat.

3.

The mating parts break downdue to motor vibration(microscopic vibration orresonance).

4.

The fused parts get damageddue to the repetition of thermalexpansion and shrinkage.

5.

The fused parts break downdu to a drop impact imposedwhen assembled or in use.

6.

Loosening due to progress inthe cracks starting with thewelds

7.

Deterioration and cracks dueto the UV rays in directsunlight

8.

1.

The fused parts getdistorted due to moisture.

2.

The body gets distorted dueto residual strains occurringat the time of molding.

3.

Poor fusion results inreduced penetration,leading to great distortion.

4.

Unserviceable(they find itrisky)

Unserviceable(they find itrisky)

1. Dimensions andshapes that resultin the breakdownof the basematerial in thegeneral part of theresin

1. Determine theoptimal value byadjusting thefusion andmoldingconditions.

2. Unify the bodyproper with highlywater-resistantand proven PPresins.

2. Keep it at or belowthe resin meltingtemperature withan overheatcontroller (at nomore than 120ºC).

3. Unify the bodyproper at the samegrade for provenPP resins.

4. Do not usecomponents thatdropped duringassembly.(Conduct thoroughprocess control.)

Consider the fusionconditions (frequency,time, and pressureapplied) under whichthe base metal breaksdown in the generalpart.

Shape the fused partswith a level differenceand provide aclearance of 0.2mm tocontain the burrs.

*

*

Subject a samplewith the worstfusion conditionsto heatdeterioration, thenperform a staticstrength test.(80°C × 2,000 hrs)

*

Subject a sample with theworst fusion conditions tothermal deterioration, thenperform a distortion test.(80°C × 2,000 hrs)

*

Check the PP resinsfor distortiontemperature andfusion startingtemperature.

*

Subject a sample withthe worst fusionconditions to thermaldeterioration, thenperform a vibrationdurability test.(80°C × 2,000 hrs)

*

Subject a samplewith the worst fusionconditions to a coldand heat repeat test.(-20°C to 120°C ×100 cycle)

*

Perform a low-temperature (-20°C)drop test (1.5m) onnew samples andthermallydeteriorated ones(80°C x 2,000 hrs).

* Prevent it fromdropping duringassembly and strictlyprohibit the use ofdroppedcomponents.

*

Subject a sample withthe worst moldingconditions to thermaldeterioration, thenperform a vibrationdurability test.(80°C x 2,000 hrs)

* Control the moldingconditions (moldtemperature andinjection pressure).

Consider a multi-point gate, film gate,and otherparameters for amold structure.

*

Weatherproofness(Sun Shine) (If thecurrent PP isproblem-free, use aproduct of the samegrade.)

*

*

Control the fusionconditions(frequency, time,and pressureapplied).

Consider the fusionconditions (frequency,time, and pressureapplied) under whichthe base materialbreaks down in thegeneral parts.

Subject a sample withthe worst fusionconditions to thermaldeterioration, thenperform a distortiontest.(80°C × 2,000 hrs)

* Subject a sample withthe worst fusionconditions to a cold,humid, and heatrepeat test. (-20°C to50°C, 90% to 120% ×100 cycle)

Subject a sample withthe worst fusionconditions to thermaldeterioration, thenperform a distortiontest.(80°C × 2,000 hrs)

If residual strains afterthe molding are great,consider usingannealing (thermaltreatment).

Control the moldingconditions (moldtemperature andinjection pressure).

* Consider the fusionconditions (frequency,time, and pressureapplied) under whichthe base metal breaksdown in the generalparts.

*

*

Check the penetrationstatus of the crosssection of the fusedparts by a polarizationmicroscope.Perform a staticstrength test on asample with the fusionconditions.

Control the fusionconditions(frequency, time,and pressureapplied).

*

* * *

* * *

Party C

Party A

Startconsideringthe fusionconditions(frequency,time, andpressureapplied).

*

Party C

Party C

Party C

Party C

Party C

Party C

Party C

Party C

Party C

Party C

Party A

Party B

Party A

Party B

Party B

Decided thatthe currentPP wasproblem-free.

*

Startconsideringthe fusionconditions

*

Startedconsideringthe fusionconditions.Startingobservationswith amicroscope.

*

*