1. Module 3: Statistical Quality Control Operations Management as a Competitive Weapon

2. 2 OM Course Framework 1. Cost - Design & Selection 2. Quality - TQM - SQC 3. Dependability - Project Management - JIT 4. Flexibility - Inventory - Supply Chain - Location - Forecasting - Aggregate Planning

3. 3 Module 03: Statistical Quality Control Learning Objectives At the end of this module, each student will be able to: 1.Discuss SQC background 2.Discuss SQC types and characteristics 3.Explain Statistical Process Control

4. 4 Module 03: Statistical Quality Control 1. SQC Background  Involves collecting, organizing, & interpreting data  Objective: Regulate product quality  Used to Control the process as products are produced Inspect samples of finished products

5. 5 Module 03: Statistical Quality Control 2. SQC Types Statistical Quality Control Process Control Acceptance Sampling Variables Charts Attributes Charts VariablesAttributes

6.  Characteristics for which you focus on defects  Classify products as either ‘good’ or ‘bad’, or count # defects e.g., radio works or not 2. SQC Characteristics Variables  Characteristics that you measure e.g., weight, length  Whole number or fractional value

7. 7 Module 03: Statistical Quality Control 3. Statistical Process Control Statistical Quality Control Process Control Acceptance Sampling Variables Charts Attributes Charts VariablesAttributes

8. 8 Module 03: Statistical Quality Control Statistical Process Control (SPC)  Statistical technique used to ensure process is making product to standard  All process are subject to variability Natural causes: Random variations Assignable causes: Correctable problems Machine wear, unskilled workers, poor mat’l  Objective: Identify assignable causes

9. 9 Module 03: Statistical Quality Control Control Charts-Theoretical Basis 95.5% of all  X fall within ± 2   X

10. 10 Control Charts-Theoretical Basis

11. 11 Control Charts-Theoretical Basis

12. 12 Control Charts-Theoretical Basis UCL LCL

13. 13 Module 03: Statistical Quality Control Control Chart Purposes  Show changes in data pattern e.g., trends  Show causes of changes in data Assignable causes Natural causes

14. 14 Module 03: Statistical Quality Control SQC Types Statistical Quality Control Process Control Acceptance Sampling Variables Charts Attributes Charts VariablesAttributes

15. 15 Module 03: Statistical Quality Control R Chart  Shows sample ranges over time Difference between smallest & largest values in inspection sample  Monitors variability in process  Example: Weigh samples of coffee & compute ranges of samples; Plot

16. 16 Module 03: Statistical Quality Control  X Chart  Shows sample means over time  Monitors process average  Example: Weigh samples of coffee & compute means of samples; Plot

17. 17 Module 03: Statistical Quality Control SQC Types Statistical Quality Control Process Control Acceptance Sampling Variables Charts Attributes Charts VariablesAttributes

18. 18 Module 03: Statistical Quality Control p Chart  Type of attributes control chart  Shows % of nonconforming items  Example: Count # defective chairs & divide by total chairs inspected; Plot Chair is either defective or not defective

19. 19 Module 03: Statistical Quality Control c Chart  Type of attributes control chart  Shows number of nonconformities (defects) in a unit  Example: Count # defects (scratches, chips etc.) in each chair of a sample of 100 chairs; Plot