SPCSimplified

How to Plug the Leaks

In Your Cash Flow!

SPC Made EasyQuick Reference Card

For SPC Video© 2008 Jay Arthur

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Analyze Stability

Processes that are "out of control" need to bestabilized before they can be improved using theproblem-solving process. Special causes requireimmediate cause-effect analysis to eliminatevariation.

The following diagram will help you evaluate stabilityin any control chart. Unstable conditions can be anyof the following:

Various trends are also considered unstableconditions. For a complete list see qimacros.com/qiwizard/stability.html. Any of these conditionssuggests that an unstable condition may exist.Consider investigating the special cause of variation.The QI Macros automatically identify these for you.

Use the Ishikawa diagram to analyze potential rootcauses.

Once you've eliminated the special causes, you canturn your attention to using the problem solvingprocess to reduce the common causes of variation:

Analyze Capability

When Cp, the process capability index, and Cpk,the centering index, are over 1.0, the process iscapable, but most manufacturers requireCp>1.33.

Use the problem solving process to identify andprevent the root causes of waste (usually belowthe lower specification limit) and rework (usuallyabove the upper specification limit). The goal, isto reduce variation so that all of your points fitwithin the specification limits, clustered around atarget.

$3.00

CapableCp>1Cpk>1

Cpk Sigma1.0 31.33 41.66 52.0 6

BEFORE

AFTER

ProblemSolving

LowerSpecLimit

UpperSpecLimit

Waste ReworkTarget

876543210

1110

9876543210

LSL USL

LSL USL

Time to Install (Before)

Time to Install (After)

3σ

-3σ

-1σ

-2σ

2σ

1σ

SPCSIMPLIFIED

SPC Made Easy

Sustain the Improvement

Purpose: Stabilize and Sustain the Improvement

Key Tools

Flowchart: Show the flow of workthrough a process including allactivities, decisions, andmeasurement points.

Control Chart: Help analyze,sustain, and monitor the currentlevels of process stability and toidentify key issues for problemsolving or root cause analysis.

Histogram: Determine the capability(i.e., the level of performance thecustomers can consistently expect)of the process and the distribution ofmeasurable data.

Sustain The Improvement (Control)

FISH Step Activity

Focus 1 Refine the process

Define 2 Identify the critical to qualityMeasure indicators (CTQs)

Improve 3 Implement the critical to qualityAnalyze indicatorsImprove

Sustain 4 Check the process for stability andControl capability

Honor 5 Review, recognize, and refocus

CycleTime

Choosing The Right Chart

VariableDataTo automate these charts, try the QI Macrosfor Excel. Download a FREE 30 day trial at

www.qimacros.com/freestuff.html.

QI Macros Control Chart WizardThe QI Macros can analyze your data and

select and run the right control chart for you.

Defect Data

To learn more about SPC, consider our onehour training video: www.qimacros.com/

spc-simplified-training-video.html

QI MacrosSample Data

XbarS

XbarR

XmRIndividuals

u Chart

c Chart

p Chart

Variable(Measured)decimal: 1.3

Attribute(counted)

integer: 1,2

np Chart

DefectsPeopleEvents

More thanone defectper item

Defective Defective?Yes/No

How many defects?

Count Defective Items?

Count Number ofDefects Per Item

Services &Manufacturing

Manufacturing

Sample Size

Constantdefects/100

Varieswrong orders/ordersmedication errorsinfections/patient days

Constantinjuries/monthPatient falls/month

Varieserrors/orderscomponents/assembliesPatient falls/days

1length or weight per itemtime/projectcost/projectinfections/1000 patient days

2-5diameters, lengthstensile strengthresistance

6-25diameters, lengthstensile strengthresistance

Samples usedto analyze largeruns of product

Time Cost

$Weight

LengthH

eight

X X X

X

Ratesor Ratios?

Individuals

Sub groups

Sub groups