Week 9 Managing Supplier Quality in the Supply Chain

1
Week 9 -Managing Supplier Quality in the
Supply Chain

• Value chains, Supplier partnering and
  development, Contingency perspective, ISO/TFS
  16949, Acceptance sampling

2
Topics

3
The Value Chain

4
The Chain of Customers

5
Managing the Supply Chain

6
Supplier Partnering - (1)

7
Supplier Partnering - (2)

8
Supplier Partnering - (3)

9
Supplier Development

10
Supplier Relationship Management Systems (SRMS)

11
The Contingency Perspective

12
A Supplier Development Program ISO/TS 16949

13
ISO/TS 16949

14
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 Demings
  position on continual improvement

15
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

16
Acceptance Sampling

17
Acceptance Levels

• Acceptable Quality Level (AQL)
• Customers may be willing to accept lots
  containing less than or equal to a specified
  defects
• Lot Tolerance Percent Defective (LTPD)
• Upper limit of the percentage of defects actually
  tolerated in accepted lots

18
Type I and Type II Errors

• Type I (producers 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 (consumers risk)
• Conclusion randomness is present and the process
  is in control or the lot is OK
• Action dont 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

19
Alpha and Beta Risks
20
Operating characteristic (OC) Curves

21
Operating characteristic curveStevenson, William
J., Operations Management, 8th Edition (mod.
09/15/04 DAB)

• Shows probabilities of accepting lots with
  various defect fractions

22
Sampling Plans

• Plan defines
• Lot size
• Sample size
• Number of samples
• Acceptance/rejection criteria

23
Single-sampling Plans

• One random sample from each lot
• Every item in sample inspected and classified
  good or bad
• If number of defects (bad) gt specified limit, lot
  is rejected

24
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) gt specified value, lot
  is rejected

25
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

26
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)

27
Summary