100-Metodos-de-Qualidade-Total

MANAGEMENT METHODS 21
switching to 'tightened inspection' when the supplier's performance is
shown to have become less satisfactory.
• Tightened inspection makes it less likely that a faulty batch will be
passed.
• Reduced inspection occurs when the supplier's performance has
consistently been better than the AOL agreed.
• BS 600] gives rules for switching from one inspection level to another
and the consequences of this.
3 Knowledge of whether defective units or defects are being inspected
for.
Background information is:
4 What is the size of the batch to be inspected?
5 Is the batch
• part of a series of batches which have already been inspected?
• the first batch of a new series?
• a 'one-off' or isolated batch?
6 The most advantageous method of sampling:
• Single sampling: a single sample of a given size is taken and a decision
made to accept, reject, or sample the whole batch if more than a
given number of defects is found.
• Double sampling: a sample is taken of a smaller size than the single
sample and then a decision is taken to accept, reject or take a second
sample.
• Multiple sampling: an extention of double sampling, allowing up to
seven samples to be taken before a decision is made.
• Sequential sampling: no fixed sample size; the samples are accumulated
until enough information is available to make a decision.
Benefits
AOL and BS 6001 give a set of rules on acceptance and rejection of
samples, based upon the sample size and number of defects found in the
sample, that can be mutually agreed between the customer and supplier,
thereby reducing disputes.
Example
An organization is purchasing containers. The critical part of the container
is the inside diameter of the curved corner. A specification has been drawn
up for the radius of the corner and an AOL of 2.5 per cent outside
specification agreed with the supplier.