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Process Performance and Quality. Chapter 5. The Costs of Poor Quality. Prevention Costs Appraisal Costs Internal Failure Costs External Failure Costs. Product/service design. Process design. Continuous improvement. Employee involvement. Customer satisfaction. Problem-solving tools.
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Process Performance and Quality Chapter 5
The Costs of Poor Quality • Prevention Costs • Appraisal Costs • Internal Failure Costs • External Failure Costs
Product/service design Process design Continuous improvement Employee involvement Customer satisfaction Problem-solving tools Purchasing Benchmarking TQMWheel Figure 5.2
Customer-DrivenDefinitions of Quality • Conformance to Specifications • Value • Fitness for Use • Support • Psychological Impressions
EmployeeInvolvement • Cultural Change • Teams
Data Analysis Tools • Checklists • Histograms and Bar Charts • Pareto Charts • Scatter Diagrams • Cause-and-Effect Diagrams • Graphs
Checklists Wellington Fiber Board Co. Headliner Defects Defect type Tally Total A. Tears in fabric //// 4 B. Discolored fabric /// 3 C. Broken fiber board //// //// //// //// //// //// //// / 36 D. Ragged edges //// // 7 Total 50 Figure 5.3
50 40 30 20 10 0 100 80 60 40 20 0 C Cumulative percentage Number of defects D A B Defect type Pareto Chart Wellington Fiber Board Co. Figure 5.3
People Materials Training Absenteeism Communication Out of specification Not available Broken fiber board Machine maintenance Machine speed Wrong setup Humidity Schedule changes Other Process Cause-and-Effect Diagram Wellington Fiber Board Co. Figure 5.3
UCL Nominal LCL Assignable causes likely 1 2 3 Control Charts Samples Figure 5.6
Using Control Charts for Process Improvement • Sample the process • When changes are indicated, find the assignable cause • Eliminate problems, incorporate improvements • Repeat the procedure
UCL Nominal Variations LCL Sample number Control Chart Examples Figure 5.7 (e)
Special Metal Screw Sample Sample Number 1 2 3 4 Rx 1 0.5014 0.5022 0.5009 0.5027 2 0.5021 0.5041 0.5024 0.5020 3 0.5018 0.5026 0.5035 0.5023 4 0.5008 0.5034 0.5024 0.5015 5 0.5041 0.5056 0.5034 0.5039 _ Control Charts for Variables Example 5.1
Table 5.1 Control Chart Factors Factor for UCL Factor for Factor Size of and LCL for LCL for UCL for Sample x-Charts R-Charts R-Charts (n) (A2) (D3) (D4) 2 1.880 0 3.267 3 1.023 0 2.575 4 0.729 0 2.282 5 0.577 0 2.115 6 0.483 0 2.004 7 0.419 0.076 1.924 8 0.373 0.136 1.864 9 0.337 0.184 1.816 10 0.308 0.223 1.777 Control Charts for Variables Example 5.1
= Sunny Dale Bank x = 5.0 minutes = 1.5 minutes n = 6 customers z = 1.96 UCLx = x + zx = = LCLx = x – zx x = /n UCLx = 5.0 + 1.96(1.5)/ 6 = 6.20 min UCLx = 5.0 – 1.96(1.5)/ 6 = 3.80 min Control Charts for Variables Using Example 5.2
UCLp = p + zp LCLp = p – zp p = p(1 – p)/n Control Charts for Attributes Hometown Bank Example 5.3
UCLp = p + zp LCLp = p - zp p = p(1 - p)/n Control Charts for Attributes Sample Wrong Number Account Number 1 15 2 12 3 19 4 2 5 19 6 4 7 24 8 7 9 10 10 17 11 15 12 3 Total 147 Hometown Bank n = 2500 Total defectives Total observations p = Example 5.3
p-Chart Wrong Account Numbers Figure 5.10
WoodlandPaper Company Control Charts for Attributes
WoodlandPaperCompany Control Charts for Attributes c = 20 z = 2 UCLc = c + z c LCLc = c – z c Example 5.4
WoodlandPaperCompany Control Charts for Attributes Example 5.4
Nominal value Process distribution Lower specification Upper specification Minutes 20 25 30 Process Capability (a) Process is capable Figure 5.12
Nominal value Process distribution Lower specification Upper specification Minutes 20 25 30 Process Capability (b) Process is not capable Figure 5.12
Nominal value Six sigma Four sigma Two sigma Lower specification Upper specification Mean Process Capability Figure 5.13
Upper specification - Lower specification 6s Cp = = x – Lower specification 3s , Cpk = Minimum of = Upper specification – x 3s Process Capability Process Capability Ratio Process Capability Index
Process Capability Intensive Care Lab Upper specification = 30 minutes Lower specification = 20 minutes Average service = 26.2 minutess = 1.35 minutes Example 5.5
Six Sigma Improvement Model • Define the current process using characteristics critical to customer satisfaction and determine gaps • Measure the work processes that affect the gap • Analyze the data focusing on process analysis • Improve the process • Control the revised process to maintain new performance levels
ASQ 6 Sigma Forum Six Sigma Implementation • Top Down Commitment • Measurement Systems to Track Progress • Tough Goal Setting • Education • Communication • Customer Priorities
ISO 9000 ISO 14000 International Quality Documentation • Environmental Management Systems • Environmental Performance Evaluation • Environmental Labeling • Life-Cycle Assessment