All of the nonprogrammed faulty vials were also detected and rejected. The vials' defects (e.g., labels with tiny wrinkles
and labels slightly out of their intended position) were almost imperceptible to the untrained eye. These defects were evidently
difficult for the buffer operator to perceive. This operator had intervals of 13 s maximum to inspect vials between each distribution
to the packing operators. The labeling machine functioned at a pace of 46 vials/min. The six packing operators had no problem
perceiving and eliminating the faulty vials that the buffer operator had missed.
The packing operator's performance ensuring MUB completion was verified by reading the weight of all MUBs at the end-of-line
station. Only one MUB with a weight equal to the lower limit was detected and set aside during the first run. Further visual
inspection by the supervisor showed that no components were missing. No out-of-limit MUBs were found during the other runs
(see Table III). This result was corroborated by the in-process control documented by the supervisor using the inspected MUBs
taken from the end of the line. All packaging runs, including shipping-box completion for market distribution, were thus considered
Table III: Results from packing-line simulation runs: Checking multiple-unit box (MUB) completion by weighing.
A further operational improvement of the above results can be achieved by reducing the time invested in manual packaging of
vials, based on the principle of economy of operator movement. Economy of movement is increased when operators use both hands
to pack two vials simultaneously. The time needed to complete MUBs could be reduced accordingly, thereby improving the balance
between the manual processing rate of the overall packing line and the optimal working regime of the labeling machine. The
amount of vials gathered and assimilated by the buffer operator could be minimized. For this purpose, packing-operator workstations
should be fitted out according to Figure 8. The conditions shown can facilitate the use of both hands for packaging manipulation.
Figure 8: Diagram of a workstation fitted out for packing operators.
The experiment demonstrated that a risk-analysis approach based on a fault-tree analysis model of the packing process achieved
upgrades and improvements. Packaging operations were arranged according to the analysis. The new arrangement resulted in a
product that was consistently packed and identified according to established requirements and current regulations.
Validation demonstrated the effectiveness of barriers against failures, which were implemented throughout the packing line,
in detecting and rejecting faulty vials. The barriers detected faulty vials deliberately included in the tests and also the
nonprogrammed faulty vials resulting from labeling-machine operation failures. The barriers did not compromise the correct
completion of multiple boxes, which reached 100%. The system therefore ensures an exceptionally low probability of product
failure and unacceptable defects at the process outlet.
This level of assurance can, in principle, significantly reduce customer complaints. It can also reduce the need for product
recalls in the worst case, which normally cause great losses for each batch withdrawn from the market.