Statistical Process Control (SPC)
| Batch Certification |
| COC on-line though internet read more... |
| Batch monitoring by SPC-files covering |
| Individual Batch Data: |
| * Averages |
| * SDs |
| * Cpk on most critical product characteristic |
| * 6-Sigma level |
| * The definition of a defect |
| * The definition of a reject |
| * FPY-level |
| * Sigma-level |
| Links & full trace ability to all rawmats and/or intermediates |
| Statistical/SPC-files on all rawmats/intermediates with |
| reject levels |
| Statistical files on all Calibration&Maintenance items |
The AIAG PPAP-manual, PPAP, 4th Edition, March 2006, Appendix F, Section F10, page 46, acknowledges the fact that bulk materials, such as solder materials, quite often are produced in a low volume production regime. The batches can be small and the number of batches can range from just a couple to no more than approximately 250 a year.
Therefore the SPC rules for a Low Volume production environment have to be applied:
- The X-Bar Chart is named WR-Chart and it is characterized by a moving range for Avg and SD.1,2
- Data-points beyond 2ä will be considered as a deviation with a potential special cause and have to be investigated.1,2
- The Cp & Cpk value on a data collection with a moving range are calculated with the following equations 3
1 Quesenberry, C.P., SPC Q Charts for start up processes and short and long runs, Journal of Quality Technology 23, pp 213-224, 1991
2 Roes, K.C.B., Does R.J.J.M., Stam R., Shewart type charts in low-volume manufacturing, Mathematical Preprint series 95-10, University of Amsterdam, 1995
3 Kane , V.E., Process Capability Indices, Journal of Quality Technology 18, pp 41-52, 1986
| 
