5 Why Analysis 1z6e5c

Why / Why (5 Why) Analysis At Honda Cars India Limited

TQM International Pvt. Ltd.

Agenda • • • •

When to use 5 Why 5 Why guidelines 3 stages of 5 Why analysis 5 Why Examples / Exercises

Seven Steps of Problem Solving • • • • • • •

Define the process Present status Analyze Do Study Standardize Review

If a problem occurs First is containment What is after Containment??

Root Cause Analysis

Five Why’s is a Root Cause analysis Tool Five Why’s is a Root Cause Analysis Tool. Not a problem solving technique. The outcome of a 5 Why’s analysis is one or several root causes that ultimately identify the reason why a problem was originated. There are other similar tools as the ones mentioned below that can be used simultaneously with the 5 Why’s to enhance the thought process and analysis.

Problem

Root Cause

Root cause analysis tool:  Ishikawa Charts (Fish Bone)  Design of Experiments  Is / Is not Analysis  5 Why’s  Cause and Effective Diagram  Statistical Data Analysis(k, Paretto Charts, Anova, etc.)

Corrective Actions

When to Use 5 Why • Customer Issues – Required for all Problem Cases – May be requested for informal complaints – May be requested for warranty issues

• Internal Issues – – – –

Quality System Audit Non-conformances First Time Quality Internal Quality Issue Machine break down

When to use 5 Why • 5 Why Analysis can be used with various problem solving methods – – – – –

Internal Problem Solving GM Drill Deep Ford 8 D (Discipline) Chrysler 8 Step DMAIC (Six Sigma)

5 Why, when combined with other problem solving methods, is a very effective tool

Five Why’s Guidelines • A cross-functional team should be used to problem solve • Don’t jump to conclusions or assume the answer is obvious • Be absolutely objective

Five Why’s Guidelines • General Guidelines – If you are using words like “because” or “due to” in any box, you will likely need to the next Why box – Root cause can be turned “on” and “off” • Will addressing/correcting the “cause” prevent recurrence? • If not what is next level of cause? – If you don’t ask enough “ Why’s ”, you may end up with a “symptom” and not “root cause”. – Corrective action for a symbol is not effective in eliminating the cause • Corrective action for a symptom is usually “detective” • Corrective action for a root cause can be “preventive” • Path should make sense when read in reverse using “Can it cause that? Test.

Five Why’s Guidelines • Even though the discipline is called 5 Why’s is not always necessary to reach 5 before the root cause of a problem is fully explained; or it may take more than 5 why’s to get the bottom of it. It will depend on the complexity of the process or the problem itself. (Normally it is recommended 3 to 5 Why’s) • In any case, 5 has been determined; as a rule of thumb, as the number at which most root causes are clearly identified. Do not worry about meeting or exceeding this number though. Just follow your thought process and let it decide how many Why’s you require to get the point where the root cause is evident.

Five Why’s Guidelines For all the Five Why’s: Ask the full question including the problem or cause behind it. If there is a problem with labeling ask : • “Why the parts were labeled incorrectly?” If the answer is unreliable database ask : • “Why is the database unreliable?” If we do not follow this approach answers to the why’s tend to loose focus on the third or fourth why.

Five Why’s Guidelines • It is said that a well designed problem is a half resolved; hence it is important to state the problem as clearly as possible. • Whenever possible define the problem in of the requirements that are not being met. This will add a reference to the condition that should be and is not.

Five Why’s – The First Why • Clear statement of the reason of the reason for the defect or failure to occur, understood even by people who are not familiar with the operation where the problem occurred. • Often the 1st Why must be a short, concise sentence that plainly explains the reason. Do not try to justify it, there will be time to do that later on in the following why’s if it is pertinent to the thought process. It is Ok to write it down even if it seems too obvious for you. (it may not seem that obvious to other persons that will read the document).

Five Why’s – The Second Why • A more concise explanation to the first statement. • Get into the technical arena, the explanation can branch out to several different root causes here. It is OK to follow each of them continuing with their own set of remaining 3 why’s and so forth.

Five Why’s – The Third Why • Do not jump to conclusions yet, follow the regular thought process even though some underlying root causes may start surfacing already. • This 3rd why is critical for a successful transition between the obvious and the not so obvious. The first two why’s have prepared you to focus on the area where the problem could have been originated; the last three why’s will take you to deeper comprehension of the problem. Visualize the process where the product went through (process mapping) and narrow down the most likely sources for the problem to occur. • You do not need to answer all the why’s at the same time. It is an investigation activity and it is good practice sometimes to go to the process and see things you could have missed at first. • You may be missing the obvious by rushing into “logical explanations”.

Five Why’s – The Fourth Why • Clear your mind from preconceived explanations and start the fourth why with a candid approach. You may have two or more different avenues to explore now, explore them all. Even if one or several of them turn out not to be the root cause of the problem, they may lead to continuous improvements.

This is a good time to include a Cause and Effect analysis and look at the 5 M’s  Method Material  Manning Machines Mother Nature

Five Why’s – The Fifth Why • When you finally get to the fifth why, it is likely that you have found a systematic cause. Most of the problems in the process can be traced to them. Even a malfunctioning machine can sometimes be caused by an incorrectly followed Preventive Maintenance or Incorrect machine parameters setup. • When you address a systematic cause, do it across the entire process and detect areas that may be under the same situation even if there are no reported issues yet. • If you have reached the fifth why and you are still dealing with process related cause(s), you may still need one or two more why’s to deep dive into the systemic cause.

Five Why’s Using the Cause and Effect diagram with the major categories, begin with the “most likely” – the questioning of “why”. Root Cause – Most Basic Reason a Problem Has or Could Occur 1. Ask “why” 3-5 times. - Why is this failure mode active ?

Progressively becomes more difficult and more thought provoking assignment.

Symptom 1 Early questions are usually superficial, obvious; the later ones “Why” Symptom 2 more substantive. “Why” Symptom 3 “Why” Symptom 4 Why did this And more “why” Probable Root cause happen ?

Five Why’s (continued) 2. Get to something “Actionable”. – Something can be done that will, if fixed, prevent problem form existing or recurring. – You or your department can do something about the probable root cause. (Do you have control over the probable root cause? )

• Revisit each sub-bone for additional causes – move back to symptom 3 and ask again, why does this symptom occur? Next, why does symptom 2 occur? Continue asking why back to the major bone (category). • Complete the entire cause and effect diagram using this same methodology. • Identify the most likely root causes and circle or cloud them – the last element in the chain you identified. (Hint: sometimes the causes most repeated are a good place to start.) • the potential root causes using data. it’s not enough that the root causes exist where the problem occurs. You must also that the root cause doesn’t exist where the problem doesn’t exist.

Five Why’s (continued) 3. Check the logic in reverse direction • • • • •

Probable root cause can it cause symptom 4 to occur Symptom 4 can it cause symptom 3 to occur Symptom 3 can it cause symptom 2 to occur Symptom 2 can it cause symptom 1 to occur Symptom 1 can it cause failure

Why is this failure mode active ? Symptom 1 Symptom 2 Symptom 3 Symptom 4

Probable Root cause

Five Why’s - (continued) 4. Check the logic from probable root cause to problem/top event. • •

If the probable root cause is eliminated or corrected, would it prevent the problem from existing or occurring ? When the probable root cause occurs, does the problem occur?

5. No procedure and no training are usually potential solutions, not a potential root cause. No Procedure

Identify the Knowledge Gap

No Training

Identify the Skill Deficiency

Five Why’s - (continued) • Another good way to identify whether the 5 Why’s was done properly is to try to organize the collected data in one sentence and define it in an understandable manner. If this cannot be done or the sentence is fragmented or meaningless chances are that there is gap between one or several of the why’s. You then must revisit the 5 Why and identify those gaps to fill them in. If there is coherence in the way that the sentence is assembled, it shows consistency on the thought process. • Something like : “ Problem Description” occurred due to “Fifth Why”. This was caused by “Fourth Why” mainly because “Third Why” was allowed by “Second Why”, and this led to “First Why”.

Five Why’s (continued) • Do not forget that the sought outcome of a 5 Why exercise is a root cause of the defined problem, not the resolution of the problem itself; that will come later. 5 Why’s is not a standalone Problem Solving technique but more of a tool to aid in this process of getting to root cause. • Do not worry about Action plans and effectiveness verification yet as that comes later; but focus more on identifying the reason that allowed the problem to happen and escape. If you can come up with a reasonable answer, the 5 Why’s exercise would be successful. If it cannot be done, then quite probably more data needs to be collected to get a better grip of the problem and them the 5 why process can be restarted.

Five Why’s – (continued) • Once again final point to ponder : A PROBLEM THAT CANNOT BE REPRODUCED IS A PROBLEM THAT HAS NOT BEEN RESOLVED YET.

• Challenge the root cause(s) that resulted from the 5 Why’s exercise to try to reproduce the defect. If you cannot there is a very big chance that you have not reached to the bottom of it yet. If you do reproduce them, move on to the Corrective Action plan and congratulate your team for a job done well.

Three Stages of Five Why’s Any 5 Why’s must address three different problems at the same time. • The first part is specific related to the process that made the defective part. (“ Why made? ”) • The second one must address the detection system that was not able to detect the defection part before it became a problem. The lack of detection of a defective product is a problem of it’s own and must be treated independently than the product problem itself. (“ Why not detected? ” )

Three Stages of Five Why’s • The third part is (Systemic) system related which allowed the product, process or system design which did not foresee the failure and built fail safe product / process or system. (“ Why did our system allow it to occur ? “)

3 – Stages, 5 – Why Analysis Define Problem

Use this path for the specific non conformance being investigated

Root Causes

Why? Why? Why? Use this path to investigate why the problem was not detected

Why? Why?

A

Why? Use this path to investigate the systemic root cause

Why? Why? Why?

B

Why? Why? Why?

Why?

C

Specific • Define the problem – Problem statement clear and accurate – Problem defines as the customer sees it – Do not add “causes” into the problem statement

• Examples: – GOOD: Customer received a part with a broken mounting pad – NOT: Customer received a part that was broken due to improper machining – GOOD: Customer received a part that was leaking – NOT: Customer received a part that was leaking due to a missing seal

Specific • Specific Problem – Why dis we have the specific non-conformance ? – How was the non conformance created ? – Root cause is typically related to design, operations, dimensional issues, etc. • • • •

Tooling wear/breaking Set-up incorrect Processing parameters incorrect Part design issue

– Typically traceable to/or controllable by the people doing the work

Specific • Specific Problem – Root Cause Examples • Parts damaged by shipping – dropped or stacked incorrectly • Operator error – poorly trained or did not use proper tools • Operator error – performed job in wrong sequence • Changeover occurred – wrong parts used • Processing parameters changed • Excessive tool wear/breakage • Machine fault – machine stopped mid-cycle

Specific What if root cause is? Operator did not follow instructions

Do we stop here?

Specific Problem Operator did not follow instructions Do standard work instructions exist ?

No Create a standard instruction

Yes

Or do we attempt to find the root cause ?

Is the operator trained ?

No Train Operator

Yes Were work instructions correctly followed ?

No

Create system to assure conformity to instructions

Yes Are instructions effective ?

Yes

Yes Do you have the right person for this job/task ?

No

No

Modify instructions & check effectiveness

Specific Column would not lock in tilt position 2 and 4

Specific Problem

Tilt shoe responsible for positions 2 and 4 would not engage pin

Can it cause that ?

Shifter assembly screw lodged below shoe preventing full travel

WHY??

Screw fell off gun while pallet was indexing Magnet on the screw bit was weak

Exceeded the bits workable life

Specific Loss of torque at rack inner tie rod t

Specific Problem

Undersized chamfer (thread length on rack)

Can it cause that ?

Part shifted axially during drill sequence

WHY??

Insufficient radial clamping load. Machining forces overcame clamp force

Air supply not maintained Various leaks, high demand at full plant capacity, bleeder hole plugs caused pressure drop

Example: 5 Why’s Why?

Why?

Had to wait for information

Missing information to complete application

Insufficient human resources

Why?

Why?

CSR did not collect all required info for customer

Most apply leaves on Monday & Friday

Why?

Why?

CSR did not know pertinent info for each types of loan

Why?

To spend long weekends with friends and family

No guidelines provided to CSR

Investigate

End

Why?

Application needs 2 approval levels

Why?

High IT system downtime

Why?

Why?

First level recommends and next level approves

Frequent Software crash

Why?

Why?

Check and balance system to manage risk

Interfacing problems between applications and credit check systems

Why?

Why?

Not confidence 1st level can evaluate effectively

Different technology platforms

Investigate

Investigate

Example: 5 Why’s First why: Why did the machine stop ? Because the fuse blew due to an overload. Second why: Why was there an overload ? Because the lubrication was inadequate. Third why: Why was the lubrication inadequate ? Because the lubrication pump was not functioning right. Fourth why: Why wasn’t the lubrication pump working right ? Because the pump shaft was worn out . Fifth why: Why was the shaft worn out ? Because there was no strainer attached where it should be , letting metal–cutting chips in.

“By asking why until you reach the root cause you can find a sustainable solution, such as attaching a strainer to the lubricating pump.”

Example: 5 Why 5 WHY ANALYSIS – GOOD EXAMPLE Employee injured Hand

Hand clamped in robot

Safety screen failed

Safety screen defective

Inadequate installation

No checks at installation

Why?

Exercises Groups to select problem to be analyzed though 5 Why’s from their respective area of work Or take one of the following problem • • • •

Steering Hard Door rattling sound Uneven tyre wear Horn works intermittently or does not work

Detection • Detection: – Why did the problem reach the customer? – Why did we did not detect the problem? – How did the controls fail? – Root cause typically related to the inspection system • Error-proofing not effective • No inspection/ quality gate • Measurement system issues

– Typically traceable to/or controllable by the people doing work

Detection • Detection – Example Root causes • No detection process in place – cannot be detected in our plant • Defect occurs during shipping • Detection methods failed – sample size and frequency inadequate • Error proofing not working or byed • Gage not calibrated

Detection Column would not lock in tilt position 2 & 4

Detection

On-line test for tilt function is not designed to catch this type of defect

Test for tilt function is applied before shifter assembly

WHY??

Process flow designed in this manner – would not detect shifter ass screw lodged below tilt shoe

Can it cause that ?

Detection Detection

Loss of torque at rack inner tie rod t Undersized chamfer/ thread length undetected

Inspection frequency is inadequate. Chamfer gage is not robust

WHY??

Process K results did not reflect special causes of variation affecting chamfer

Can it cause that ?

Systemic • Systemic – Why did our system allow it to occur? – What was the breakdown or weakness? – Why did the possibility exist for this to occur? – Root Cause typically related to management system issues or quality system failure • Rework/repair not considered in process design • Lack of effective Preventive Maintenance system • Ineffective Advanced Product Quality Planning (DFMEA, PFMEA, Control Plans)

– Typically traceable to or controllable by People • • • •

Management Purchasing Engineering Policies/Procedures

Systemic Issues • Systemic – Helpful hint: The root cause of the specific problem step is typically a good place to start the systemic stage. – Root Cause Examples • • • •

Failure mode not on DFMEA, PFMEA Believed failure mode had zero potential for occurrence New product/process not properly evaluated Product, sub-process, Process changed creating a new failure cause • DFMEA’s, PFMEA’s generic – not specific to the process • Severity of defect not understood by team • Occurrence ranking based on external failure only, not actual defects

Systemic Systemic Root Cause Column would not lock in tilt position 2 and 4

Detection for tilt function done prior to installation of shifter assembly

PFMEA did not identify a dropped part interfering wit tilt function

WHY??

First time occurrence for this failure mode

Can it cause that ?

Systemic Loss of torque at rack inner tie rod t

Systemic Root Cause

Ineffective control plan related to process related to process parameter control (chamfer)

Can it cause that ?

Low severity for chamfer Control

WHY??

Dimension was not considered an important characteristic – additional control not required Insufficient evaluation of machining process and related severity levels during APQP process

Corrective Actions • Corrective Actions – Corrective action for each root cause – Look for 2 to 3 alternatives actions for each cause and choose the best one – Corrective actions must be feasible – Foresee consequential effects of each action – If customer approval required for corrective action, this must be addressed in the 5 why timing – Corrective actions include documentation updates and training as apporpriate

5 – Why Critique Sheet • General Guidelines: – Don’t jump to conclusions…don’t assume the answer is obvious – Be absolutely objective – A cross-functional team should complete the analysis

• Step 1 : Problem Statement – State the problem as the Customer sees it…do not add “cause” to the problem statement

5 – Why Critique Sheet • Step 2 : Three Stages (Specific, Detection, Systemic) – There should be no leaps in logic – Ask why as many times as needed. This may be fewer than 5 or more than 5 Why’s(Normally it is 3 to 5 why’s) – There should be a cause and effect path form beginning to end of each path. There should be data/evidence to prove the cause and effect relationship – The path should make sense when read in reverse form cause to cause – this is the “can it cause this” test (e.g. – did this, therefore this happened) – The specific problem stage should tie back to issues such as design, operations, supplier issues, etc. – The detection stage should tieback to issues such as DFMEA, PFMEA, control plans, error-proofing, etc.

5 – Why Critique Sheet • Step 3: Corrective Actions – There should be a separate corrective action actions for each root cause. If not does it make sense that the corrective action applies to more than one root cause? – The corrective action must be feasible – If corrective actions require Customer approval, does timing include this ?

• Step 4: Lessons Learned – Document what should be communicated as Lessons Learned • • • •

Within the plant Across plants At the supplier At the Customer

– Document completion of in-plant Look Across (communication of Lessons Learned) and global Look Across

5 Why Analysis Examples Group Exercise • Review a 5 Why using the Critique Sheet and what you have learned – Note: These are actual responses as sent to our Customers! – Has probable root cause been determined for: • Non-conformance stage • Detection stage • Systemic stage

– Do corrective actions address root cause? – Have Lessons Learned /Look Across been noted? – If any above answers are “no”, what recommendations would you make to the team working on the 3 stages of 5 Why?

Missing O-ring on part number K10001J

Why ? Part missed the O-ring installation process

Why ?

Why did they have to rework? Parts had to be reworked

Why ? Operator did not return parts to the proper process step after rework

Why ?

This still a systemic failure needs to be addressed, but it’s not the root cause.

No standard rework procedures exist

Missing threads on fastener part number LB123

Why ? Did not detect threads were missing

Why ? Sensor to detect thread presence was not working

What caused the sensor to get damaged ?

Why ? Sensor was damaged

Why ?

This is still a systemic failure & needs to be addressed, but it’s not the root cause of the lack of detection.

No system to assure sensors are working properly

Summary of Key Points • • • •

• • • • • •

When do you use it? Use a cross-functional team Never jump to conclusions Ask “WHY” until you can turn it off Use the “Can it cause that? ” test for reverse path Strong problem definition as the customer sees it Specific stage – Typically applies to people doing work Detection stage – Typically applies to people doing work Systemic stage – Typically applies to people – Start with root cause of specific stage Corrective actions with date and owner Document lessons learned and look across