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Lecture 14A - Managing Supplier Quality in the Supply Chain (Chapter 9). Value chains, Supplier partnering and development, Contingency perspective, ISO/TFS 16949, Acceptance sampling. Topics. The Value Chain. The Chain of Customers. Managing the Supply Chain.
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Lecture 14A -Managing Supplier Quality in the Supply Chain (Chapter 9) Value chains, Supplier partnering and development, Contingency perspective, ISO/TFS 16949, Acceptance sampling SJSU Bus. 142 - David Bentley
Topics SJSU Bus. 142 - David Bentley
The Value Chain SJSU Bus. 142 - David Bentley
The Chain of Customers SJSU Bus. 142 - David Bentley
Managing the Supply Chain SJSU Bus. 142 - David Bentley
Supplier Partnering - (1) SJSU Bus. 142 - David Bentley
Supplier Partnering - (2) SJSU Bus. 142 - David Bentley
Supplier Partnering - (3) SJSU Bus. 142 - David Bentley
Supplier Development SJSU Bus. 142 - David Bentley
Supplier Relationship Management Systems (SRMS) SJSU Bus. 142 - David Bentley
The Contingency Perspective SJSU Bus. 142 - David Bentley
A Supplier Development Program: ISO/TS 16949 SJSU Bus. 142 - David Bentley
ISO/TS 16949 • ISO/TS 16949 based on a model: • Quality management system • Management responsibility • Resource management • Product realization • Measurement, analysis and improvement • Closely aligned with ISO 9000:2008 SJSU Bus. 142 - David Bentley
Acceptance Sampling • Definition: statistical quality control technique “applied to lots or batches of items before or after a process, to judge conformance with predetermined standards” (from Stephenson) • Acceptance sampling is controversial • Some believe it to conflict with Deming’s position on continual improvement SJSU Bus. 142 - David Bentley
Acceptance Sampling • Form of inspection applied to lots or batches • Before or after a process, not during the process • Purpose: determine whether lot satisfies predetermined standards SJSU Bus. 142 - David Bentley
Acceptance Sampling SJSU Bus. 142 - David Bentley
Type I and Type II Errors • Type I (producer’s risk) • Conclusion: non-randomness is present and the process is out of control or the lot is bad • Action: stop the process which was OK or reject lot • Reality: randomness is present and the process is in control or the lot is OK • Type II (consumer’s risk) • Conclusion: randomness is present and the process is in control or the lot is OK • Action: don’t stop the process; continue making defects or reject lot • Reality: non-randomness is present and the process is out of control or the lot is bad SJSU Bus. 142 - David Bentley
Alpha and Beta Risks SJSU Bus. 142 - David Bentley
Acceptance Levels • Acceptable Quality Level (AQL) • Customers may be willing to accept lots containing less than or equal to a specified % defects • Relates to Type I risk (α or Producer’s risk) • Lot Tolerance Percent Defective (LTPD) • Upperlimit of the percentage of defects actually tolerated in accepted lots • Relates to Type II risk (β or Consumer’s risk) SJSU Bus. 142 - David Bentley
Operating characteristic (OC) Curves SJSU Bus. 142 - David Bentley
1 0.9 0.8 0.7 0.6 Probability of accepting lot 0.5 0.4 0.3 0.2 3% 0.1 0 0 .05 .10 .15 .20 .25 Lot quality (fraction defective) Operating characteristic curveStevenson, William J., Operations Management, 8th Edition (mod. 09/15/04 DAB) • Shows probabilities of accepting lots with various defect fractions SJSU Bus. 142 - David Bentley
Sampling Plans • Plan defines: • Lot size • Sample size • Number of samples • Acceptance/rejection criteria SJSU Bus. 142 - David Bentley
Single-sampling Plans • One random sample from each lot • Every item in sample inspected and classified: good or bad • If number of defects (bad) > specified limit, lot is rejected SJSU Bus. 142 - David Bentley
Double-sampling Plans • Upper and lower defect limits set for each lot • Results of initial sample • Defects ≤ lower limit: lot accepted • Defects ≥ higher limit: lot rejected • Defects between two limits: take 2nd sample • If 2nd sample needed, compare number of defects from both samples to third value • If number of defects (bad) > specified value, lot is rejected SJSU Bus. 142 - David Bentley
Multiple-sampling Plans • More than 2 samples • 2 limits specified for each sample • Cumulative number of defects compared to limits for each successive sample • Defects ≤ lower limit: lot accepted • Defects ≥ higher limit: lot rejected • Defects between two limits: continue sampling SJSU Bus. 142 - David Bentley
Acceptance Sampling in Continuous Production • Differs from lot-by-lot sampling • Typically alternate between 100% and sampling inspection • Described in DOD MIL STD 1235C (1988) SJSU Bus. 142 - David Bentley
Summary SJSU Bus. 142 - David Bentley