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What is 5-Whys

Whenis used for?

Howis used?

Failure Modes

Root cause

Occurrence

Detection

Systemic Root cause

Corrective Actions

Examples

Questions and Answers

5 Whys Training


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What is 5-Whys

5-Whys is a tool used to determine the root cause(s) and

corrective actions for any specific problem.

An important idea behind the 5 Whys is to asked ourselves five

times, Why it happened?

The 5 whys is considered similar to a Problem Definition

Tree used for Shainin, with the difference that the 5 whys

also search for occurrence, detection and systematic root cause.


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When is used 5-Whys

5- Whyshas to be used whenever a5-phases report is generated

to solve a problem. This is a Divisional Procedure

requirements indicated on # 812 Procedure Corrective andPreventive Action.

When we use a 5-Whys, we assumed that the root cause and

corrective actions are unknown. It is important to know thefailure mode which requires to have the evidence (product)

available to analyze it and confirmed the failure mode.


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How is used 5-WhysFailure Mode:

First, we have to know the failure mode, this is the mechanism of

the failure, it means howitfailed.

Examples:

Problem:

Customer could notassembly harness connector with our mating

part at the Engine plant.

Failure Mode:

Mixed parts, specifically, part number 10456119 mixed in

container of model 10456226.


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Problem: Failure at M&D test.

Failure Mode:

Master Cylinder brake fluid leak between reservoir and

machined body.

Problem: Noise at RH front suspension.

Failure Mode:

Noisy damper

Once we know failure mode of problem, we start with the

5-Whys process.

Customer problem description andsupplier failure mode


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Root Cause:

5-Whys system helps us identifying the root cause of a problem.

This root cause is defined in three paths:

Occurrence Root Cause: Physically what happened at ourmanufacturing flow that generate this failure mode.

Detection Root Cause:What failed at our current detection system

Operator instructions, SPC, final testers, poka-yokes,

assessments, and reviewsto let the problem reachs our customer.Systemic Root Cause: What is weak in our Quality System, that

requires improvement eg. TPM, PFMEA, lack of knowledge of

Customer Interfaces, APQP, Build of Process/Design, etc.

How is used 5-Whys


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5 Whys Format


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Root Cause Examples:- Occurrence:

Worn tool due to inadequate preventive maintenance frequency

Final Test Stand operator was not warned of model change.

therefore, in the Fianl tester he mixed two part numbers in

same box and then it were shipped.

How is used 5-Whys


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5-Whys Root Cause of Occurrence


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Root Cause Examples:- Detection:

Final tester is not capable to review correct tool crimping. there is not any

test at process which could detect it.

Operator sorts mixed pieces, however this method is not effective, due

similarity on pieces.

Sample size taken by auditor was not big enough for mixed pieces detection.

There are not Label layered audits to ensure correct delivery of labels.

How is used 5-Whys


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5-Whys Root Cause of Detection


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Systemic-Root cause examples

PFMEA did not consider this failure mode.

Lack of knowledge of customer interfaces.

Drawing does not consider it as critical characteristic

(KPC)

Preventive maintenance has not appropriate frequencies,Worn life tool was not evaluated.

Model Changes procedure does not include inspection of

first samples.

How is used 5-Whys


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5-Whys Root Cause Systematic


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How is used

Corrective Actions:

After we found root cause of occurrence, detection and systemic ,

we have to generate irreversible corrective actions.It is also important to turn off/on the problem in order to proceed

with the corrective actions implementation.

These corrective actions have to be written at right side of

5 Whysprocess diagram.


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Improved 5 WhysAfter training provided

P/N 001190 could

not be assembled;

Burr on the outside

dia of the spindle

Burrs on the outside

dia of the spindle

Worn stamping tool

Tool exceeded

recommended wear life

PM interval did not

take into account toollife or wear

No procedure when

creating PMs to

determine tool life

based on history or

mfg recommendation

Define Problem

Parts passedinspection process

Inspector did not

follow the inspection

procedure properly

Inspector did not know to

inspect for this criteria

1. Not properly trained

2. No standard inspprocedure/criteria

1. No formal operator

training system

2. No standard insp

procedure or visual

aids/boundary samples

Not robust PM on

tool life

No FTQ history

available

Inadequate tool validation

Lack of PMProcedural

Specific

nonconformance

being investigated

Why the problem

was not detected

Systemic root cause

WHY?

WHY?

WHY?

WHY?

WHY?

WHY?

WHY?

WHY?

WHY?

WHY?

WHY?

A

B

C

Corrective Actionwith responsibility

Date

1. Replace worn tool 3/20

1. Train operator

3/20

WHY?

4/1

4/15

1. Conduct PM on all dies

after each run and

maintain history (KJ).

2. Develop strategic PM

intervals and requirements

on all dies based on

history and mfg

recommendations. (LB)3. Develop a company

wide training program with

clear requirements for

trained or certified (ST)

4. Review all inspection

procedures and improve

visual aids and criteria (LB)

5. Begin tracking FTQ at

stamping to monitor PM

improvement (PP)

6. Set up layered audits for

training matrix (CB)

7. Set up layered audits for

PM completion (DG)

8. Update PFMEA/PCP/TPM

5/20

4/21

3/25

4/1

DO

DO

DO/ACT

ACT

ACT

CHECK

CHECK

4/1

ACT

ACT

5/1 CHECK

CHECK

DO/ACT

Black = Suppliers initial response

Blue = Updated 5Why thru QFS process

Red = PDCA

4/1

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4/1 DO/ACT

PLAN

PLAN

PLAN

2. Add step in procedure

for creating new PM to

review manufacturers

recommendation and

history to determine

PM interval (GT)

2. Develop insp standards

for all products (JM)

3. Develop visual aids forinspection criteria for allproducts (DG)


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5 Whys Example


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5 Whys Example


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5 Whys Example

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