Quality Management

Quality Management Quality Defined: • Conformance to requirement:

meeting specification • Fitness for use: Quality is in the eye of the beholder

Dimensions of Quality • • • • • • •

Performance Features Reliability Durability Serviceability Aesthetics Perceived Quality

Measuring Quality Manufacturing Oriented • Defect rates • Scrap rates Customer Oriented • Customer satisfaction survey

Typical Causes for Quality Problems • Workmanship • Materials • Maintenance of process and equipment • Poor product design

Quality and Productivity Productivity = Output / Input

Poor quality leads to: • • • •

Low profit Low efficiency High Leadtime High inventory

Cost of Quality Cost of Nonconformance • Failure Cost – Internal – External

Cost of Quality Assurance• Appraisal cost • Prevention cost

Statistical Quality Control • Process Control – test random samples of output to determine if the process is under control

• Acceptance Sampling – test random sample from a lot to decide whether to accept or reject the the whole lot

Control Process • Define • Measure • Compare to standard • Take necessary action • Evaluate action

Variation Types • Random (common) • Assignable (special)

Designing Control Charts • Sample size • Sampling Frequency • Location of control limits