100-Metodos-de-Qualidade-Total

22 100 METHODS FOR TOTAL QUALITY MANAGEMENT
Table 1 AQL sampling information
Inspection level Code letter Sample size Acceptance criteria
Accept Reject
G 32 2 3
II 80 5 6
JII K 125 7 8
Table 2 Operating characteristic curves of sampling plans G, J and K
Circumstances G K
Quality of submitted 5% chance of 2.5% chance of 0.5% chance of
batch bettcr than AQL rejection rejection rejection
Quality as bad as 5% 80% chance of 78% chance of 70% chance of
defective acceptance acceptance acceptance
Quality as bad as 10% 37% chance of 19% chance of 7% chance of
defective acceptance acceptance acceptance
The customer will be inspecting containers, so that defective units are to
be inspected: the container is either right or wrong. The normal inspection
level has been selected, the batch size is 1,000 containers and the batch is
part of a series. Reference to BS6001 gives the information in Table 1.
The implications in terms of sampling risk of selecting one or other of
these levels can be found by a study of the operating characteristic curves
of plans G, J and K (Table 2).
It must be remembered that a lower inspection level does not imply a
lower level of acceptable quality but an increase in the risks associated with
the acceptance of a single batch. In a series of samples, we have to take
into account the fact that some whole batches will be inspected and
rejected 100 per cent and this will affect the outgoing quality. This allows
you to make an informed judgement about which sampling plan is best for
your use.
Reference
Guide to the Use of BS 6001: Sampling Procedures.