Quality, Quality Control

Lee Buddress, Ph,D., C.P.M.

Robert G. Gleason Professor and Director

Supply and Logistics Program

Portland State University

Quality

How would you define ‘Quality’?

Quality DefinitionsManufacturing-Based - Philip Crosby

“Quality means conformance to requirements”

Value-Based - Feigenbaum “Quality means best for certain customer

conditions. These conditions are (a) the actual use, and (b) the selling price of the product”

Quality DefinitionsCustomer-Based - Juran

“Quality is fitness for use”Customer-Based - AT&T

Quality is meeting customer expectations.”

Philip CrosbyQuality is Free, pp. 15-16

Quality has much in common with sex. Everyone is for it (under certain conditions, of course). Everyone feels they understand it (even though they wouldn’t want to explain it). Everyone thinks execution is only a matter of following natural inclinations. (After all, we do get along somehow). And, of course most people feel that all problems in these areas are caused by other people. (If only they would take time to do things right).

Quality Is Quality Free?Can We Achieve 100% Quality?

ShingoDifference Between Errors and Defects

Errors Cause Defects Defects Occur Because of Errors

Three Types of Inspection Self-Inspection Successive Checks - Next Person Source Inspection (Check for Errors that

WILL cause Defects Identify Errors, Fail Safe the Process

Control Charts Processes Have Natural Variation Fundamental Question:

Natural Variation or Process Change? That is what Statistical Process Control is All

About Key Assumptions:

Sample is RANDOMLY selected Defects are randomly distributed throughout the lot

Cautionary Note: Works Best for High Volume, Repetitive Tasks

SamplingFor Defects (What is Quality of Lot?)For Conformance to Specification (No

More Than X% Defective)

Control Chart TypesAttribute Charts (things counted)

P-chart: Proportion Defective C-chart: Number of Defects Focus is on PRODUCT output

Variable Charts X-chart: Sample Means R-chart: Range Means Focus in on PROCESS, itself

Control Chart Problem Indicators

One Data Point Outside Control LimitTwo Data Points in Zone ThreeFive Consecutive Data Points on One

Side of the MeanTrend - Five Successive Points in a

TrendErratic BehaviorSudden Change in Behavior

5 ‘M’s Ishikawa Diagrams (Fishbone)

Man Machine Method Materials Maintenance

Why-WhyGoal is to Get Past Symptoms to

Underlying CauseAsk Why Until No Further Useful

Information is Forthcoming

Quality and Supply ChainsCustomer RequirementsSpecificationsSupplier SelectionProcess CapabilityQuality Evaluation

First Article Inspection Defect Detection Defect Prevention

Quality and Supply ChainsSupplier Certification

ISO 9000 Incoming Receiving

Legal Requirements for Inspection Latent Defects

Learning Curves

Questions, Comments, Observations, Conclusions,

Arguments?