3x5 Why-why Analysis - A new appr approach oach for root root cause cause anal analysis ysis
1st Supplier Quality Day * 27NOV09 ST Shenzhen Plant
3x5 Wh Why y Why Why Ana Analys lysis is Con Conten tentt
A.
The 3x5 Why Project Background
B.
The 3x5 Why Method
C.
The 3 x 5Why Focus
D.
Templates
ST target is to share with our suppliers a common approach for problem problem solving solving methods methods especially especially for for “3x5 Why why why “ tool , to get complete, exhaustive FA report and to avoid any recurrence.
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Naze-Na NazeNaze ze / 3x5Wh 3x5Why-A y-Anal nalysi ysis s Project Background
A. The Naze-Naze Project Background * Naze Naze = “Why” “Why” in Japa Japanes nese e
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Naze-Na NazeNaze ze / 3x5Wh 3x5Why-A y-Anal nalysi ysis s Project Background The Situation
寻根究底
1.The Need of our Customers
* To understand each 8D-Report from semiconductor and passive suppliers in depth * To understand if the problems are solved in a way that they never reoccur Remark: Having reached ppm-level, our customer fails enable ST and their customers / suppliers to look at each 8D-Report in depth.
2. Improvement of 8D-Quality by Why-Why-RCA (Root Cause Analysis)
In 2009, ST takes the next step and has started a project with our key suppliers. Focus on: * Implementing Why-Why-Analysis for non-conforma non-conformance nce and and non-detection non-detection aspects including system root causes * Getting a common understanding of a sustainable problem solving process * Having a comprehensive documentation of each failure which is understandable on a general technical knowledge level for our customers & management. Hint: This project is part of the 8D improvement improvement initiative which is measured acc. acc. Toyota scoring methodology 4
Naze-Na NazeNaze ze / 3x5Wh 3x5Why-A y-Anal nalysi ysis s Project Background Motivation ST is the Top 3 automotive electronics supplier.
All automotive customer request is “ZERO FAILURE”
However, ST devices didn’t reach the target : •
some failure were reoccurrences, special caused by quality excursions material.
•
quality level is improving very slowly.
there is a strong need for persistent improvement
⇒
•
requires systematic application of lessons learned
•
prerequisite: full understanding of real root causes (technical and non-technical)
=> method: method: 5 why why analysis analysis (naze naze), from from Toyota Toyota
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Naze-Naze / 3x5Why-Analysis Project Background Role of Naze-Naze Champions Internal and Supplier’s 5Why-Champion Name: - Reviewed and Agreed by STM management Task:
- Leading of internal 5Why project, roll-out to all divisions and plants, Develop to all key suppliers. - Encourage and support 8D-Engineers in applying the 5Why problem solving method - Assure that technical & systemic root cause is analyzed and eliminated for “prevent” and “escape” aspect=> avoidance of recurrence. - To be trained and evaluated by ST QA. - Involving management team into Naze-Naze Method.
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B. The Naze-Naze Method
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Naze-Naze / 5Why-Analysis Method Historical Background Although the 5-Why problem solving technique has been popularized by the Japanese, this common-sense concept has been around for quite some time. • • • • • • • •
For want of a nail a shoe (hoof) was lost, for want of a shoe a horse was lost, for want of a horse a rider was lost, for want of a rider an army was lost, for want of an army a battle was lost, for want of a battle the war was lost, for want of the war the kingdom was lost, and all for the want of a little horseshoe nail.
John Gower‘s dated approximately 1390 AD. The earliest known written version of the rhyme above (often taught to British children)
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Naze-Naze / 5Why-Analysis Method Historical Background (cont.) One of Ohno´s habits was to repeat asking 1. why the problem happened 2. why the problem was not prevented -why–why-why-why….. until the real root cause was found. This habit has been preached to overseas transplants of Toyota. All Toyota employees are trained through their daily jobs to find out problems, root causes, countermeasures in this way. His habit became a Toyota´s culture. This culture is one of the keys of Toyota´s success today, that is realized by enthusiastic problem finding skill of every employee.
Mr.KAIZEN (1912-1990) Mr.KAIZEN „Taiichi Ohno“ Ohno“ (1912
Former executive vice president of Toyota who established Toyota-ProductionSystem, which is known by “Kanban”. His philosophy is still alive in today's Toyota way.
"Ask ‘why’ five times about every matter." 1. "Why did the robot stop?" The circuit has overloaded, causing a fuse to blow. 2. "Why is the circuit overloaded?" There was insufficient lubrication on the bearings, so they locked up. 3. "Why was there insufficient lubrication on the bearings?" The oil pump on the robot is not circulating sufficient oil. 4. "Why is the pump not circulating sufficient oil?" The pump intake is clogged with metal shavings. 5. "Why is the intake clogged with metal shavings?" Because there is no filter on the pump. Link to the information source: http://www.asahi.com/jinmyakuki/TKY200509290213.html http://www.toyota.co.jp/en/vision/traditions/mar_apr_06.html
Having no problems is the biggest problem of all 9
Naze-Naze /5Why-Analysis Method Purpose of Naze Naze Analysis (5 x Why) • Question: How are you sure that your Naze-Naze Analysis is performed properly? • Answer: When real root causes are identified,
there should be no reoccurrence of failures! • The purpose of Naze-Naze Analysis: To prevent reoccurrence of failures by implementing correct countermeasures on real root causes
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Naze-Naze / 5Why-Analysis Method What does “Problem” mean?
“Problem” is defined as a gap between “the way it should be” and “the way it is”.
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Naze-Naze / 5Why-Analysis Method Problem description
First step of problem solving!
If a problem is described wrongly, the result of problem solving will be also wrong. Example of wrong description
This is not a joke! Real example from a workshop with engineering colleagues
Customer give us feedback very late when a delivered sample was out of spec., and we can not make improvement timely.
An out-of-spec. sample was produced and delivered to customer.
Then, describe “standard” and “actual” in comparison
Think from customer’s view 12
Naze-Naze / 5Why-Analysis Method Basics of Naze-Naze Analysis What to do
Grasp the situation Pursue root causes
Analyze with GENCHI-GENBUTSU 1. Organize & narrow down the problem A complex problem
plural individual problems
2. Localize the problem Perform GENCHI-GENBUTSU 3. Evaluate the situation of occurrence
Implement effective C/M Why to do
Grasp the pattern
Fix the real root cause and never let it reoccur 1. Shift from “reactive firefighting” to “preventive countermeasure”
C/M to prevent a reoccurrence
Firefighting will result in reoccurrence 2. Master the key points of Naze-Naze to pursue real root causes Grasp every factor of the failure regularly, orderly
No reoccurrence should happen when the real root cause is fixed 13
Naze-Naze / 5Why-Analysis Method Grasp the situation accurately
Initial Problem Perception (large, vague or unclear) Clarify the problem
Shortcut to real root causes!
Preparation for 5 x Why 3 elements to grasp the situation ① Organize and narrow down the problem ② Localize the problem ③ Evaluate the situation, how the problem
happened
Locate the Point of cause
Locate the Point of cause
to clarify what when where who how in GENCHI GENBUTSU 14
Naze-Naze / 5Why-Analysis Method Initial Problem Perception (large, vague or unclear)
1
Clarify the problem
2
Locate the Point of cause
2
Point of cause
3 5 x Why is a key step in the problem solving
Basic Cause/Effect Investigation
Direct Cause
4
5 Why investigation
5
Root Cause
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Countermeasure Follow Up and Check
G R A S P T H E S I T U A T I O N
C A U S E I N V E S T I G A T I O N
把 握 真 实 情 况
进 行 原 因 调 查 分 析 Source: TMUK PPS
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Naze-Naze / 5Why-Analysis Method Grasp the situation accurately 1. Organize and narrow down the problem ・・・
Often a detected failure is a combination of complex problems ＜Example＞ Contamination on a product
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Naze-Naze / 5Why-Analysis Method Grasp the situation accurately 2. Localize the problem
・・・
Go back the processes from where the problem was detected ＜Example＞ Iron ball particle on a product
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Naze-Naze / 5Why-Analysis Method Grasp the situation accurately Localize the problem in the history
・・・
If different direct causes were set in different timing or many persons were involved, list up all the events chronologically with evidences. Evaluate each action if it was correct or not.
Example
Email, letter, documents, etc…
l e p m t E x a y c h a r o r t s i H
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Naze-Naze / 5Why-Analysis Method Grasp the situation accurately 3. Evaluate the situation, how the problem happened ・・・
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Naze-Naze / 5Why-Analysis Method Fact analysis
find important factors
・・・
• Compare no problem time and problem time • If not yet clarified, use Ishikawa diagram • Always consider with 5M1E
5M1E Man Machine Material Method Measurement Environment 20
Naze-Naze / 5Why-Analysis Method
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Naze-Naze / 5Why-Analysis Method For your successful Naze-Naze analysis
Understand the function and construction of the object well
• Product: understand the function and construction with parts,
drawings, etc… • Management: confirm the process and function with working process
flow, rules, documents, etc… • Search in two dimensions of “Produced” and “Delivered”
Non-conformance
Non-detection
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Naze-Naze / 5Why-Analysis Method Drill for important factors deeper with Naze-Naze analysis Do not jump immediately to investigate countermeasures. Do Naze-Naze analysis to search real root causes.
Direct Cause 5 Why Investigation
Root Cause
Repeat asking “why” at least 5 times. However this does not mean to repeat asking meaninglessly “why” just 5 times, but to find the real root causes. 23
Naze-Naze / 5Why-Analysis Method Difference between “containment” and “preventive” measures ＜Example＞ Machine stop
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Naze-Naze / 5Why-Analysis Method Difference between “Technical” and “System” root cause ＜Example＞ Machine stop
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Naze-Naze / 5Why-Analysis Method Example entered into excel-template
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Naze-Naze / 5Why-Analysis Method How Yokoten works in Toyota
*Depending on the severity, escalation level is decided.
水平扩展、 水平扩展、水平展开
Horizontal Deployment
C/M should be implemented not only in technical aspect, but also system aspect**.
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Naze-Naze / 5Why-Analysis Method Key Points： ① Define “1st Why” from principle ② Describe only things differing from normal state ③ Verify the hypothesis as soon as a hypothesis is made ④ Do not diffuse the problem (avoid subjective issues) ⑤ Avoid searching for causes under psychological (心理上的)aspects ⑥ Describe simply (not two facts in one sentence) ⑦ Avoid ambiguity (含糊不清的unclear expression like “bad” or “insufficient”) ⑧ Clarify the comparative object when an adjective is used ⑨ Repeat “why” until a cause which can lead to a preventive
countermeasure is found to avoid a reoccurrence ⑩ Read backwards and confirm if Naze-Naze story is correct
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Naze-Naze / 5Why-Analysis Method ① Define “1st Why” from principle
Principle: something very basic Focus on the problem phenomenon and define “1st Why” upon the principle of the problem Problem
1st Why
2nd Why
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Naze-Naze / 5Why-Analysis Method Thoroughly Pre-Investigation first
These 2 causes are to be found through thoroughly pre－ investigation. They are not necessarily part of 5Why.
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Naze-Naze / 5Why-Analysis Method ② Describe only things differing from normal state
< Bad example > Dust level increased in clean room
Machines create dust
Machines are operated with full capacity
Production volume is big
Demand increased
No business can be continued with this root cause !
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Naze-Naze / 5Why-Analysis Method ③ Verify the hypothesis as soon as a hypothesis is made • Verify the hypothesis immediately if possible, even during NazeNaze analysis. • Verify by facts based on: SANGEN-SHUGI (Genba 现场 , Genbutsu 现物 , Genjitsu 现实), interview, reproduction test, etc…
Principle of the three “Gen”s – real place, real thing and reality. Two methodologies:
my eyes and my legs. These are all I need to see, to judge, to consider, to decide.
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Naze-Naze / 5Why-Analysis Method ④ Do not diffuse the problem < Bad example > Motor overheate d
Insufficient lubricant
Avoid subjective issues, i.e. ＜Bad example＞ personal skills
The story was diffused due to missing description of what “insufficient” is Lubricant forgotten
Insufficient maintenance managemen t
Manager does not know GENBA
Wrong manager at the post
⑤ Avoid searching for causes under psychological aspects It is difficult to make effective countermeasures against mental to prevent reoccurrence < aspects Bad example > Why Mr.A got his head injured
Mr.A hit his head at the edge of the ceiling
Why
Why
C/M
Mr.A did not pay attention
Mr.A was careless
Be careful when walking
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Naze-Naze / 5Why-Analysis Method ⑥ Describe simply + when, where, how, etc…
Describe simply with subject + verb Do not describe two facts in one sentence （risk to miss other causes)
< Bad example >
Only 1 subject in one sentence
Be careful with „and, or, therefore, because, thus“
The battery has not been replaced for long time and the pointer cannot be turned on.
Separate into 2 sentences The battery has not been replaced for long time
The pointer cannot be turned on Problem
Problem
The pointer cannot be turned on
The battery has run down The battery has run down The spring lost contact with the bulb
More potential causes are successfully found!
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Naze-Naze / 5Why-Analysis Method ⑦ Avoid ambiguity Describe concretely Examples of inappropriate texts (to be avoided) XX is bad
XX is insufficient
Operator not enough experienced
XX shortage
XX not thoroughly done
X
Operator did not remember the changeover procedure
Describe concretely
Operator did not know where the stop switch located Inexperienced operator was disposed at this process
⑧ Clarify the comparative object when an adjective is used XX is too big for YY
XX is bigger than YY
The bolt diameter is big
XX is longer than YY
X
Bolt diameter is too big for the hole diameter The hole diameter is too small for the bolt diameter 35
Naze-Naze / 5Why-Analysis Method ⑨ Repeat “why” until a cause which can lead to a preventive countermeasure is found to avoid reoccurrence A containment measure cannot prevent a reoccurrence. （See Page 4）Considering the daily operation, stop “why” when a preventive measure which we can maintain is found.
⑩ Read backward and confirm if Naze-Naze story is correct
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Naze-Naze / 5Why-Analysis Method Practical hints for your problem solving workshop* Team member selections: • Expert team + the persons who were directly involved in the problem. This is not to punish the individual faults, but is to perform “grasp the situation” with facts. • Manager Question technique: • During “grasp the situation”, avoid questioning based on assumptions and concentrate on gathering facts. Otherwise this might guide the team into a wrong direction. Manager’s attitude: • Think about why the problem was not predicted nor discovered by manager. Is there anything to improve?
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Naze-Naze / 5Why-Analysis Method
Last but not least: It is necessary to keep on learning in your daily work in order to improve your Naze-Naze skills.
Is it a reoccurrence? 「Product B was mixed in product A 」 After a measure was implemented 「Product C was mixed in product A 」
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Naze-Naze / 5Why-Analysis Method Practical hints for successful Yokoten*
For a successful Yokoten, the key point is in “receiver side”.
If the product or process is different, it is easy to excuse “not applicable“.
Instead of saying “not applicable” quickly, think how the Yokoten case can be interpreted to your own processes.
Every case is an opportunity of On the Job Training.
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Naze-Naze / 5Why-Analysis Method Before you sign on a problem solving report: Go back with “therefore”
• Is 5 x Why logically done till system aspect? • Are you convinced that the problem will not happen again? • Is the report easy-to-understand from customer’s view? Can you present it to your customer? Mindset of coach
The reason that students (my colleagues) are not learning is because the teacher (I) is not teaching.
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C. The 3 x 5Why-Focus
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Naze-Naze / 3x5Why-Analysis Focus What is the 3x5Why-Root Cause Analysis?
General: •
The 5-Why Root Cause Analysis technique is a practical and proven tool for elimination of root causes.
•
Failing to address the deeply rooted seed of the problem means it will likely recur.
The •
Method:
Because
The problem-solver simply asks a Why-question approximately five times in series to analyze a certain aspect.
•
Why
Through the 3x5Why-method the root cause can be discovered… 1.
in the Manufacturing process to PREVENT failures (non-conformance)
2.
in the Quality test inspection process, in order to PROTECT the customer from test escapes (non-detection), and
3.
to identify/PREDICT weaknesses in the (Quality) Management or System, in order to exclude recurrence (-> learning organization towards zero defect).
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Naze-Naze / 3x5Why-Analysis Focus Avoid this Pattern The following sequence of Questions should not be followed:
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Naze-Naze / 3x5Why-Analysis Focus Basic Solution Pattern The following sequence of Questions is recommended:
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Naze-Naze / 3x5Why-Analysis Focus Identification of System-Rootcause Purpose of 5Why-Analysis: Identification of the individual (1) Technical and Drill Deep
(2) System Root Cause
Definition System Root Cause: Organizational causes, that lead to a deviation. Example: Missing work flows, unclear descriptions and/or responsibilities not defined Solution or definition of measures is up to the management System Root Cause Recommendation: In the Fishbone-branch for „methods“ organizational weaknesses can be considered. 45
Naze-Naze / 3x5Why-Analysis Focus Summary Why-Why Analysis
Ask for system root causes for each technical root cause
non-detection: same as above! 46
D. Templates
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Naze-Naze / 3x5Why-Analysis Template Naze-Naze / 5Why-Basic Word-Template Corrective Action with Responsibility
Date
1 x 5Why :
A
DD.MM.YYYY
2 x 5Why :
B
DD.MM.YYYY
C1
DD.MM.YYYY
C2
DD.MM.YYYY
NON- Define Problem
CONFORMANCE (PREVENT) ASPECT: Use this path for the specific nonconformance bein investi ated
3 x 5Why :
WHY?
NON-DETECTION
Technical Root Causes
WHY?
PROTECT ASPECT: Use this path to Investigate why the problem was not detected
System Root Causes PREDICT ASPECT : Use these fields to investigate the systemic root cause
WHY?
WHY?
WHY?
WHY?
A
WHY?
WHY?
WHY?
C1
WHY?
C2
Ref. No. (RMA, DMR, etc)
The template (word
.
…
or excel file) can be used as a Date
WHY?
DD.MM.YYYY summary sheet for root cause investigation. Product / Process
Location
B
WHY?
Content Latest Rev Date
It is not mandatory toCountry use exactly Electrical component City/ DD.MM.YYYY Communicate to Customer Date: DD.MM.YYYY this form, but it might be a helpProcess in Change tracing back Break Point Date: DD.MM.YYYY Problem Resolution Complete Implement System Change Date: DD.MM.YYYY
Lessons Learned: the systemic root cause for both aspects,
non-conformance and non-detection.
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Naze-Naze / 3x5Why-Analysis Template Define Problem:
TECHNICAL ROOT-CAUSE
SYSTEM ROOT-CAUSE
Result Investigation Report:
SYSTEM-ROOT CAUSE (PREDICT) NON-CONFORMANCE (PREVENT): Use this path for the specific non-conformance b eing in vested
Use these fields to i nvestigate the systemic or Managem ent-Root Cause
... Why?
Why?
Why?
Why?
Why?
Why?
Why?
e t a l p m e t – l e c x E
NON-DETECTION (PROTECT): Use this path to investigate why the probl em was not detected
Why?
Why?
Why?
Why?
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Naze-Naze / 3x5Why-Analysis Template Example: Processability due to bad solderability
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Naze-Naze / 3x5Why-Analysis Template Example: Weak Processability due to bad solderability (cont.)
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