Lot Norm

Lot Norm 2018-05-29T16:40:06+00:00

Pages 71 and 72 of the USA Department of Defence document MIL-PRF-19500P of 10 April 2014 requires manufacturers of JANS products to implement controls on lots, to detect and reject maverick lots. Specifically, an extract of D.3.9.5.h.3 of the above specification states:

” The manufacturer shall ensure that the lot’s mean and standard deviation is consistent with
previous lots. After initial qualification a minimum of 5 lots must be statistically monitored for spread and location. Significant changes between lots for average and standard deviation shall be addressed by engineering comment. Lot-to-lot variation control in spread and location shall be performed for each critical parameter. Control shall be based on a moving average of at least 5 lots, see D.3.9.1. This control is for comparing lots only ….”

This specification is implemented in yieldHUB as follows. It avoids any analysis in a spreadsheet which would take hours otherwise and would be subject to human error.

Lots are automatically placed on a dashboard for review by engineers.

  1. They can select up to 10 lots of a JANS Part Number to be analysed for variation at a time
  2. If they select only one lot, the latest 10 which are not found already to be Atypical
    i.e. described as  “Approved-Atypical” or equivalent, are loaded into the report to be
    compared with the one you selected
  3. Any of the lots can be assigned a status “Approved”, “Pending” and “Approved-Atypical” in the yieldHUB database based on the engineers review of the statistical performance of each lot
  4. User can search the database for lots with a given status

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