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Engineering Management Six Sigma Quality Engineering Week 7 Analyze Phase
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Page 1: 618week7-Analyze.ppt

CSUN EngineeringManagement

Six Sigma Quality Engineering

Week 7

Analyze Phase

Page 2: 618week7-Analyze.ppt

Chapter 6 Outline

Process Map Inputs characteristics

Cause & Effect Fishbone Diagram (Minitab) C&E Matrix (Excel)

Failure Mode & Effect Analysis (FMEA) Process Capablity

Cpk Cp

Minitab Tutorial In this session you will learn how to:

·    Produce X and R charts·    Produce histograms with normal curves·    Perform a process capability analysis

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Detailed Process Map Example

PICKLE RINSE

(Y's)Acid freeDebris removed

(Y's)Surface cleanliness- Removel of sand- Removal of rust- 'Defect free'

SHOTBLAST

(Y's)Surface cleanliness (dust / rust free)Surface roughness

HANG ON PENDANTS

STAND

UNCOATED FITTINGS

(x's)C TimeC Shot size / mix of sizesN HumidityS Type / Material / Original size of gritN Effectiveness of seperatorN Product geometryN Condition of machineN Dust arrestor conditionS Amount of work being shotblastC Time between pickle and shotblastN Operator

(x's)C TimeN Product geometryN OperatorS Rocked / Not rockedS Method of packing

(x's)C Make up of mix, Concentration and % of Hydrochloric Acid, Hydrofluoric Acid, Activol, WaterC Pickling timeS Age of mix / SGN Quality of work / containerN Containers / tankN Product geometryS Packing methodN OperatorS Shotblast prior to pickling

LYE BATH

(Y's)Uniformity of fluxNo excess flux (removed by Dry ing Oven)

DRYING TUNNEL

(Y's)Dry castingsWarm castings

DIP IN ZINC BATH / BUMP

(Y's)Coating Quality- Thickness of z inc / z inc alloy layers- Uniformity of coverage- Total coverage- Appearance- Roughness / tex ture- Composition of coating

WATER SPRAY KNOCK OFF

RUMBLE

(Y's)AppearanceSmooth Finish

(Y's)Zinc : Zinc Alloy thicknessAppearance (brightness)Removal of ash (c leanliness)Fitting temperature COATED

FITTINGS

(x 's)C Speed of chain / time in bathC Temperature of lye bathC Make up of lye bathS Cleanliness of lye bathN Geometry of partsS Pendant sty le / orientation of workS Amount per pendantS Weight of product per minute put through bath (Heat removal + heat pickup)S Time from shotblastN Humidity

(x 's)C Speed of chainS Temperature of tunnelN Geometry / Mass of fittingsN HumidityS Air velocity

(x 's)S Quality of supplier / materialsC Temperature of z incS Level of drossS Level of leadN Geometry / mass of fittingsN Operator (Skimming surface / agitation of pendants)S Quality of pendantsN Specifiacation (BS, ISO, EN)S Rate of withdrawalS Fluidity of z incN Power of bumper unit

(x 's)S Water volumeN Water temperatureC Speed of chainN Mass / Geometry of fittings (Rate of cooling)

(x 's)C TimeC Number of fittings per loadN Geometry of fittingsS Condition of rumbling barrel

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Characterising Inputs

Inputs can be classified as one of three types Controllable (C)

• Things you can adjust or control during the process• Speeds, feeds, temperatures, pressures….

Standard Operating Procedures (S)• Things you always do (in procedures or common sense things)

• Cleaning, safety….

Noise (N)• Things you cannot control or don not want to control

(too expensive or difficult)• Ambient temperature, humidity, operator...

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Example

Machining a shaft on a lathe

Inputs (x’s)Rotation speedTraverse speedTool typeTool sharpnessShaft materialShaft lengthMaterial removal per cutPart cleanlinessCoolant flowOperatorMaterial variationAmbient temperatureCoolant age

Outputs (Y’s)DiameterTaperSurface finish

CCCCCCCSCNNNS

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The Eight Steps in Cause and Effect Analysis

Define the Effect

Identify the Major Categories

Generate Ideas

Evaluate Ideas

Vote for the Most Likely Causes

Rank the Causes

Verify the Results

Recommend Solutions

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Cause & Effect (Fishbone Diagram)

Objectives

• To understand the benefits of Cause & Effect Analysis

• To understand how to construct a C & E Diagram

Analysis

• A method a work group can use to identify the possible causes of a problem

• A tool to identify the factors that contribute to a quality characteristic

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Uses of C & E (Fishbone Diagram)

Visual means for tracing a problem to its causes

Identifies all the possible causes of a problem and how they relate before deciding which ones to investigate

C & E analysis is used as a starting point for investigating a problem

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C&E (Fishbone Diagram)

Effect

• The problem or quality characteristic

• The effect is the outcome of the factors that affect it

Effect

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Causes (Fishbone Diagram)

All the factors that could affect the problem or the quality characteristic

Five Major Categories

• Materials

• Methods

• People

• Machines

• Environment

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Effect

PeopleMethodsMaterial

Machine Environment

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Cause and Effect (Matrix)

Benefit• Gain new knowledge and perspectives by sharing

ideas with others• Helps us understand our processes• Provides a basis for action

• Whenever a problem is discovered, using C&E analysis forces us to take a proactive stance by seeking out causes

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Rating of Importance to

Customer

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Total

Process Step Process Input

1 02 03 04 05 06 07 08 09 0

10 011 012 013 014 015 016 017 018 019 020 0

0

Total 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Lower Spec

Target

Upper Spec

1

2

3

4

5&6

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C&E Matrix

Instructions

This table provides the initial input to the FMEA and experimentation. When each of the output variables (requirements) are not correct, that represents potential "EFFECTS". When each input variable is not correct, that represents "Failure Modes".

1. List the process output variables 2. Rate each output on a 1-to-10 scale to importance to the customer3. List process input variables (from the process map)4. Rate each input's relationship to each output variable using a 0, 1, 3, 9 scale 5. Select the high ranking input variables to start the FMEA process; Determine how each selected input variable can "go wrong" and place that in the Failure Mode column of the FMEA.

This table provides the initial input to the FMEA and experimentation. When each of the output variables (requirements) are not correct, that represents potential "EFFECTS". When each input variable is not correct, that represents "Failure Modes".

1. List the process output variables 2. Rate each output on a 1-to-10 scale to importance to the customer3. List process input variables (from the process map)4. Rate each input's relationship to each output variable using a 0, 1, 3, 9 scale 5. Select the high ranking input variables to start the FMEA process; Determine how each selected input variable can "go wrong" and place that in the Failure Mode column of the FMEA.

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FMEA

It is an approach to:• Identify potential failure for a product or a process• Estimate risks that are associated with causes• Determine actions to reduce risks• Evaluate product design validation plan• Evaluate process current control plan

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FMEA types

There are two types:• Process: Will focus on Process Inputs• Design: Will used to analyze product designs before

they are released to production

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The use of the FMEA

Improve processes before failure occur (Proactive approach)

Prioritize resources to ensure process improvement efforts are beneficial to customers

Track and document completion of projects It is a living document. It will be updated and

reviewed all the time

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Inputs & Outputs to FMEA

Inputs Process Map C&E Matrix Process History Process technical procedures

Outputs Actions list to prevent causes Actions list to detect failure modes Document history of actions taken

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FMEA step-by-step

For each process input, determine the ways in which the input can go wrong- the failure modes.

What is the process

step/input under investigation?

In what ways does the input go wrong?

What is the impact on the Output Variables

(Customer Requirements)

or internal requirements?

How

sev

er is

the

eff

ect

to t

he

cust

omer

?

What causes the input to go wrong?

How

oft

en d

oes

caus

e of

FM

oc

cur?

Process Step/Input

Potential Failure Mode

Potential Failure Effects Potential Causes

OCC

SEV

What can go wrong with input

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FMEA step-by-step

For each failure mode associated with the inputs, determine the effects of the failures on the customer.

What is the process

step/input under investigation?

In what ways does the input go wrong?

What is the impact on the Output Variables

(Customer Requirements)

or internal requirements?

How

sev

er is

the

eff

ect

to t

he

cust

omer

?

What causes the input to go wrong?

How

oft

en d

oes

caus

e of

FM

oc

cur?

Process Step/Input

Potential Failure Mode

Potential Failure Effects Potential Causes

OCC

SEV

What the effect on outputs?

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FMEA step-by-step

Identify potential causes of each failure mode.

What is the process

step/input under investigation?

In what ways does the input go wrong?

What is the impact on the Output Variables

(Customer Requirements)

or internal requirements?

How

sev

er is

the

eff

ect

to t

he

cust

omer

?

What causes the input to go wrong?

How

oft

en d

oes

caus

e of

FM

oc

cur?

Process Step/Input

Potential Failure Mode

Potential Failure Effects Potential Causes

OCC

SEV

What are The causes?

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FMEA step-by-step

List the current controls for each cause or failure mode (Prevent/Detect).

How are these Found or prevented?

Prevent Detect

Current Controls

What are the existing controls and procedures (inspection and test) that prevent/detect either

the Cause or Failure Mode? Should include an SOP number.

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FMEA step-by-step

Create Severity, Occurrence, and Detection rating scales.

– Severity of effect- importance of effect on customer requirements. It is a safety and other risks if failure occurs.» 1= Not Severe, 10= Very Severe

– Occurrence of cause- frequency in which a give Cause occurs and creates Failure Mode. Can sometimes refer to the frequency of a failure mode.» 1= Not Likely, 10= Very Likely

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FMEA step-by-step

Create severity, Occurrence, and Detection rating scales.

– Detection- ability to:» Prevent the causes or failure mode from occurring or

reduce their rate of occurrence» Detect the cause and lead to corrective action» Detect the failure mode» 1= Likely to Detect, 10= Not Likely at all to Detect

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FMEA step-by-step

Risk Priority Number:• After rating we get the output on an FMEA Risk

Priority Number. It is calculated as the product of Effects, Causes, and Controls

RPN= Severity X Occurrence X Detection

Effects Causes Controls

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FMEA step-by-step

Dynamics of the Risk Priority Number:• The team defines the rating scales 1-10 for the

severity, Occurrence, and Detection ratings. The team choose the levels and numbers:

• How severe is it: Not Severe = 1

Somewhat = 3

Moderately = 5

Very Severe = 10

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FMEA step-by-step

Dynamics of the Risk Priority Number:• The team defines the rating scales 1-10 for the

severity, Occurrence, and Detection ratings. The team choose the levels and numbers:

• How often does it Occur? Never/rarely = 1 Sometimes = 3 Half the time = 5 Always = 10

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FMEA step-by-step

Dynamics of the Risk Priority Number:• The team defines the rating scales 1-10 for the

severity, Occurrence, and Detection ratings. The team choose the levels and numbers:

• How well can you detect it? Always = 1 Sometimes = 3 Half the time = 5 Never = 10

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FMEA step-by-step

Determine recommended actions to reduce high RPN’s:

Ho

w w

ell

can

yo

u d

ete

ct

cau

se o

r F

M?

What are the actions for

reducing the occurrence of the

Cause, or improving

detection? Should have actions only on high RPN’s or

easy fixes.

Who is responsible for the

recommended action?

What are the completed actions

taken with the recalculated RPN?

Be sure to include

completion month/year.

DET

RPN

SEV

OCCResponsible Actions Taken

RPN

Actions Recommended

DET

What can be done?

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FMEA step-by-step

Take appropriate actions and recalculate RPN’s

Ho

w w

ell

can

yo

u d

ete

ct

cau

se o

r F

M?

What are the actions for

reducing the occurrence of the

Cause, or improving

detection? Should have actions only on high RPN’s or

easy fixes.

Who is responsible for the

recommended action?

What are the completed actions

taken with the recalculated RPN?

Be sure to include

completion month/year.

DET

RPN

SEV

OCCResponsible Actions Taken

RPN

Actions Recommended

DET

Assign responsibleParties

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Process Capability Study

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Cpk & Cp

•Cpk incorporates information about both the process spread and the process mean, so it is a measure of how the process is actually performing.

•Cp relates how the process is performing to how it should be performing. Cp does not consider the location of the process mean, so it tells you what capability your process could achieve if centered.

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Process Capability Study

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Non-normal distributions

•Use Capability Analysis (Nonnormal) to assess the capability of an in-control process when the data are from the nonnormal distribution. A capable process is able to produce products or services that meet specifications.

•The process must be in control and follows a nonnormal distribution before you assess capability. If the process is not in control, then the capability estimates will be incorrect.

•Nonnormal capability analysis consists of a capability histogram and a table of process capability statistics

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Questions? Comments?