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 Definitions  Manufacturing-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 Definitions  Customer-Based - Juran  “Quality is fitness for use”  Customer-Based - AT&T  Quality is meeting customer expectations.”

Philip Crosby Quality is Free, pp 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?

Shingo  Difference 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

Sampling  For Defects (What is Quality of Lot?)  For Conformance to Specification (No More Than X% Defective)

Control Chart Types  Attribute 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 Limit  Two Data Points in Zone Three  Five Consecutive Data Points on One Side of the Mean  Trend - Five Successive Points in a Trend  Erratic Behavior  Sudden Change in Behavior

5 ‘M’s  Ishikawa Diagrams (Fishbone)  Man  Machine  Method  Materials  Maintenance

Why-Why  Goal is to Get Past Symptoms to Underlying Cause  Ask Why Until No Further Useful Information is Forthcoming

Quality and Supply Chains  Customer Requirements  Specifications  Supplier Selection  Process Capability  Quality Evaluation  First Article Inspection  Defect Detection  Defect Prevention

Quality and Supply Chains  Supplier Certification  ISO 9000  Incoming Receiving  Legal Requirements for Inspection  Latent Defects  Learning Curves

Questions, Comments, Observations, Conclusions, Arguments?