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Packing-Line Improvement Based on a Fault-Tree Analysis Approach
This article focuses on upgrading and improving a packing process to comply with current good manufacturing practices. The authors sought to maintain proper quality assurance for finished products.
Figure 3: Packing-process fault tree showing the main start section and the major unwanted event.
A BP 4100 technical balance (Sartorius, Göttingen, Germany) with a 0–4100-g range and a resolution of ± 0.1 g is located at
the end of the line. An operator places each MUB and reads its weight to verify that it has been filled. The MUB is then sealed,
and the corresponding label is affixed. Shipping boxes are also checked in the same way using a QC1500NNP scale (Sartorius
) with 0–1500-kg range and ± 200-g resolution. Shipping boxes are then sealed and labeled accordingly.
Figure 4: Packing-process fault tree showing the branch that follows from product temperature-requirement failure.
This arrangement is designed to ensure good coordination among all operators regarding manual performance. The time each packing
operator took to complete an MUB, including visual inspection, was measured as 160–170 s, with a margin of 10 s for recovery.
The conveyor was therefore set to a linear velocity of 900 cm/min. The labeling machine had an optimum working speed of 45–47
vials/min. Hence, the buffer operator has an important task, which is to control vial distribution through the conveyor at
intervals of 12–13 s. The buffer operator avoids bottlenecks by gathering the overflow of labeled vials to operators, and
releasing the collected vials when the labeling machine is interrupted.
Fault-tree analysis of the packing process
Figure 5: Packing-process fault tree showing the branch following from failure in primary-information imprinting.
An FTA model was specially developed for the packing process by representing failure events with logical operators to form
a logical information flow chart (see Figure 3). The special symbols employed in this flow chart are explained in the literature
(7). The major unwanted event was defined as "Finished-product quality noncompliance resulting from packing process." All
cause–effect fault events flow downward. Any of the following failures can provoke the major unwanted event:
Failure in product temperature requirements during the packing process (which exclusively applies to products that require
refrigeration)
Failure of packing material to display the corresponding primary product information (e.g., batch manufacturing date, batch
number or identification code, and batch expiration date)
Lack of correspondence between product specifications, printed packing material (e.g., vial labels, cartons, leaflets, MUBs,
and shipping labels), and documentation (e.g., QA release authorizations, packing order, and records created during packaging)
Failure to comply with cleaning and line-clearance requirements for areas involved in the packing process, including labeling
machine and all workstations, to avoid product-batch cross contamination.
Arturo Toledo Rivero is the head of the research and development department at LIORAD Laboratories, Ave. 27A No. 26402, La Lisa, Havana, Cuba, tel. 1537 2717935, fax 1537 2717899, atliorad@infomed.sld.cu.
Articles by Arturo Toledo Rivero
