six sigma 9 analyze-2

8/10/2019 Six Sigma 9 Analyze-2

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Upendra Kachru SIX SIGMA

Six Sigma – Analyze Phase




Step in Analyze Phase

Process Map Value Stream Mapping

Cause & Effect

Fishbone Diagram (Minitab)

C&E Matrix (Excel)

Process Capability Cpk

Cp




• Defines value from the customer’s perspective• All of the actions and tasks, both value added and

non-value added, required to bring an item (an idea,information, product or service) from its inception

through delivery. – These include actions to process information from the

customer and actions to transform the product on its wayto the customer.

• Value streams vary in scope: reach beyond theenterprise to single process size

What Is a Value Stream?




Value and Waste

Value is that for the sake of which a process exists; e.g., to produce designs that meet customer needs within the constraints

of time, money, and regulatory requirements.

Waste in a process is anything not needed to get the job done to

the satisfaction of the customer and other stakeholders.

Only processing adds value.

All the rest is waste:

– Waiting

– Moving

– Inspecting or Approving – Reworking




Ohno’s 7 Types of Waste

• Inventories of goods awaiting processing or consumption• Unnecessary transport of goods

• Defects in products

• Overproduction of goods not needed

• Unnecessary processing• Waiting by employees for process equipment to finish work or

for an upstream activity to complete.

• Unnecessary movement of people




Value Categories

– Value categories as defined below

• Value Added: – Physically transforms the “thing” going through the process

– Must be done right the first time

– Meaningful from the customer’s perspective (is the customer willing

to pay for it?)

• Value Enabling:

– Satisfies requirements of non-paying external stakeholders

(government regulations)

• Non-Value Added

– Everything else




A Simple Example

Pick Up Paper Walk to Stapler Staple Paper

Walk to Desk Put Down Paper

Time: 1 sec.

Distance: 0

Time: 5 sec.Distance: 20 ft.

Time: 5 sec.

Distance: 20 ft.

Time: 2 sec.

Distance: 0

Time: 1 sec.Distance: 0

Total Time: 14 sec.Total Dist: 40 ft.

Value Added Time: 4 sec. Value Added Dist: 0

Value Added Time: 28%

Info: Where to place stapleInfo: Location of stapler

Excess Travel

Customer Need:Stapled pages




Value Stream Process Steps

1. Prepare

2. Gather Data & Develop Current State

3. Develop Future State & Action Plan

4. Execute to Plan

5. Align




Value Stream Process

Step 1 - Prepare• Gather Preparatory Information

– Document the Case for Change

– Define the Scope (start and end of process)

– Identify the Requirements

– Review/establish Measurements

• Set Logistics for Event

– Participants

– Location

– Materials – Meals/Refreshments

– Etc.





Step 2 - Gather Data (Develop Current State)

• Observe and gather data

– Walk the value stream - see the actual work place

– Follow and make notes about “item” and information flow

– Gather data for each step in the flow

• Trigger/done actual lead time output

• Actual cycle time on time delivery staffing

• Defect rate batch sizes overtime

• Quality variations work in process

• Map the flow of items

• Map the flow of information

• Add data and issues




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't want to control

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




Characterising Inputs- Example

Machining a shaft

on a latheInputs (x’s)

Rotation speed

Traverse speed

Tool typeTool sharpness

Shaft material

Shaft length

Material removal per cut

Part cleanliness

Coolant flow

Operator

Material variation

Ambient temperature

Coolant age

Outputs (Y’s)

Diameter Taper

Surface finish

C

C

CC

C

C

C

S

C

N

N

N

S




Detailed Example

KLNS

(Y' AcDe(Y's)Surf - Re- Re- 'De

TB

(SS

N

NDT A

A

N

(x'CCNSNNNNSCN(x's)C TN PN OS RS M(x's)C Ma HydC PicS AgN QuN CoN Pr S PaN OpS Sh

BATH

(Y's)Uniformity ofNo excess fl

TUNN

(Y's)Dry castinWarm cas

IN ZINH / BU

(Y's)

Coating- Thickn- Unifor - Total- Appea- Rough- Comp

TER SPNOCK

RUM

(

A

S

(Y's)Zinc : AppeRemoFittin

COAFITTI

(x's)

C Speed of c

C Temperatu

C Make up of

S Cleanliness

N Geometry

S Pendant st

S Amount per

S Weight of p

(Heat remo

S Time fromN Humidity

(x's)

C Speed of

S Tempera

N Geometr

N Humidity

S Air veloci

(x's)

S Quality

C Tempe

S Level

S Level

N Geom

N Operat

S Quality

N Specifi

S Rate oS FluidityN Power

(x's)

S Wat

N Wat

C Spe

N Mas

(Rate

(x'CCNS





Step 3 – Future State & Action Plans

• Discuss the ideal state

• Develop the future state map

• Develop action plans & cadence tracking

– Build draft time line for implementation

• Communication & training as required

Designing for 6-sigma

• Reduce the number of parts in a product

• Reduce the number of steps in a process




Action Plan Template#

Process Step or

Function

Original

Problem Action ItemsPerson

Responsible

Due

Date Metrics and Comments

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17




Swimlane Diagram

Prepare ArchitecturalDrawings

Prepare

Engineering

Drawings based on

Loads

Modify

Engineering

Drawings

Subcontract Detailing

to Fabricator

Subcontract Detailing

To Detailer

Prepare Details

Check details

& modify asappropriate

Check details& modify as

appropriate

Check details

& modify as

appropriate

Check details

& modify asappropriate

Return modifieddetails to fabricator

Structural

Engineer

Architect

General

Contractor

Fabricator

Detailer

RFI Process for Placing Drawings




Example: RFI Process for Placing Drawings

Check RFI

& modify drawing as

appropriate

Structural

Engineer

LEAD

TIME

PROCESS

TIME

Q?

What is the percentage of actual processing

time compared to the amount of time it sits in

someone’s In tray?





Assumptions:

8 hour work days (weekends not deducted)

Sections of RFI log where time spent was not recorded are

not included in the calculation.

Sample entry :

Lead time

(LT)

Time spent

to respond

to RFIs

(VAT)





Value Stream Mapping (Designing for 6-sigma)

Current State Future State with

Rework

Future State without

Rework

Future State with

EDI

Steps % Steps % Steps % Steps %

87 100 67 100 32 100 11 100

73 84 46 69 11 34 3 27

12 14 19 28 19 60 6 55

2 2 2 3 2 6 2 18

Total steps

Non-Value adding

Non-value adding but

necessary

Value-adding


• Reduce the number of steps in a process

• Reduce the number of non-value adding steps




Cause & Effect (Fishbone) Diagram

C & E 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 qualitycharacteristic

• 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




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

characteristic

• Five Major Categories

– Materials

– Methods – People

– Machines

– Environment

The problem or quality

characteristic

The effect is the outcome of the factors that affect it

Cause & Effect (Fishbone) Diagram

C & Eff M i




The C&E matrix is constructed from the fishbone diagram using the

following procedure:1. List the process output variables

2. Rate each output on a 1-to-10 scale to importance to the

customer

3. 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;

6. Determine how each selected input variable can "go wrong" and

place that in the Failure Mode column of the FMEA.

Cause & Effect Matrix




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

C & Eff t M t i




• 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

Eight Steps in Cause and Effect Analysis:

Effect


C & Eff t M t i





Process Capability




20 25 30

Upper

specification

Lower

specification

Nominal value

Process Capability

This process is capable

Process distribution

Process capability is the ability of the process to meet the design

specifications for a service or product.

• Nominal value is a target for design specifications.

• Tolerance is an allowance above or below the nominal value.

P C bili




Capable Process

A stable process that meets customer requirements.

Capability assessments for unstable processes, may not be indicative

of how the process is actually performing.

Spec limits or tolerances for product quality characteristics are:

– Characteristic of the part/item (product) in question

– Based on functional design considerations

– Related to/compared with an individual part measurement

– Used to establish a part’s conformance to design intent

Process Capability




Process is not capable

20 25 30

Upper

specification

Lower

specification

Nominal

value

Process distribution

Process Capability



Process Capability




Process capability ratio, C p, is the tolerance width divided by6 standard deviations (process variability).

Process Capability Ratio, Cp

C p =Upper specification - Lower specification

6

Process Capability

A

B

SpecificationLimit

SpecificationLimit

Cpk =A divided by

B

P C bili




C pk = Minimum of Upper specification – x3s

x – Lower specification3s

,

=

=

Process Capability Index, C pk , is an index that measures the

potential for a process to generate defective outputs relative to

either upper or lower specifications.

Process Capability Index, Cpk

We take the minimum of the two ratios because it gives the worst-

case situation.

Process Capability

P C bili




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.

Process Capability

E ample: Intensi e Care Lab




Example: Intensive Care Lab

Upper specification = 30 minutes

Lower specification = 20 minutes

Average service = 26.2 minutes

= 1.35 minutes

The intensive care unit lab process has an average turnaround time

of 26.2 minutes and a standard deviation of 1.35 minutes.

The nominal value for this service is 25 minutes with an upper

specification limit of 30 minutes and a lower specification limit of

20 minutes.

The administrator of the lab wants to have three-sigma performancefor her lab. Is the lab process capable of this level of performance?

Intensive Care Lab




C pk

=Minimum of

Upper specification – x

3s

x – Lower specification

3s,

= =

Upper specification = 30 minutesLower specification = 20 minutes

Average service = 26.2 minutes

= 1.35 minutes

Intensive Care Lab

C pk = Minimum of 26.2 – 20.0

3(1.35),

30.0 – 26.2

3(1.35)

C pk = Minimum of 1.53, 0.94 = 0.94ProcessCapability

Index

Assessing Process Capability

i C




C p =Upper specification - Lower specification

6

C p =30 - 20

6(1.35)= 1.23 Process Capability Ratio

Before Process Modification

Upper specification = 30.0 minutes Lower specification = 20.0 minutes

Average service = 26.2 minutes = 1.35 minutes C pk = 0.94 C p = 1.23

Intensive Care Lab

Does not meet 3 (1.00 C pk ) target due to a shift in mean (Note

variability is ok since C p is over 1.0)

Assessing Process Capability

P C bilit




Statistical Assessment of Process Capability

• Get Process in Statistical Control

• Statistical Assessment (Minitab or Excel)

– Construct histogram of individual measurements

– Compute probability of exceeding specifications P(•)• Empirically (observed)

• Convert to defects per million (DPM) and sigma capability

• Compute process capability indices … C p, C pk

Process Capability

P C bilit




Control Charts for Attributes

p -chart: A chart used for controlling the proportion of

defective services or products generated by the process.

p = p(1 –

p)/nWhere

n = sample size

p = central line on the chart, which can be either the historical average

population proportion defective or a target value.

z = normal deviate (number of standard deviations from the average)

Control limits are: UCL p = p+z p and LCL p = p−z p – –

Process Capability




Process Capability Requirements

• Process must be normally distributed

• Process must be in control

• Process capability result:

– > 1.34 = capable

– < 1.33 = not capable

– = 1.33 = barely capable

– > 5 or 10 is “overkill”, excessive resource use

Process Capability




Process Capability

Spreadsheet Template

Process Capability Study





Process Capability




Alternatives for Improving Process Capability

• If bias

– Recenter and recompute P(•), dpm, and sigma capability

• If too much variation

– Sort by 100% inspection

– Widen tolerance

– Use a more precise process (e.g., better or new technology)to reduce variation

– Use statistical methods to identify variation reduction

opportunities for existing process

Process Capability

Process Capability




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

Process Capability

Process Capability




How it helps

• A Process Capability study is the end result of the analysis done

on process output data.

• A Process Capability study reflects what our customer sees.

• It indicates what our short term and long term situation looks

like.

• Recognise however that our processes need to be stable (in

statistical control) as well as capable.

• Before anything, we must have faith in our measurements, hence

the need for a measurement system analysis.

Process Capability




C l i c k t o e d i t c o m p a n y s l o g a n .

six sigma 9 analyze-2

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