The packaging machine must, first of all, have a capacity at least equal to the nominal production of the line (capacity at full production). It is then necessary to distinguish whether the product to be packaged arrives at the packaging machine in a single lane (e.g. cartons, bags) or is multi-lane channeled (e.g. rectangular bottles or jars) or in bulk on flow conveyors (e.g. round bottles or jars, cans ).
If the product to be packaged arrives at the packaging machine in a single row (e.g. cartons, bags), the conveyor belt that connects the packaging machine to the upstream production line does not allow for accumulation to happen. Thus, in the event of the packaging machine being stopped, the upstream machine (e.g. labeler or filler) will also be immediately stopped by an electrical signal exchanged between the two machines. When the packaging machine is restarted, another exchange will restart the upstream machine. In this case, the stop and restart condition does not affect the capacity (or speed) required of the packaging machine, so it is sufficient that its capacity is at least equal to the nominal production of the line (capacity at full production).
If the product to be packaged arrives at the packaging machine in a multi-lane flow (e.g. rectangular bottles or jars) or in bulk on flow conveyors (e.g. round bottles or jars, cans), the conveyor belt that connects the packaging machine to the upstream production line allows accumulation. Thus, in the event of a stop of the packaging machine, the upstream machine (e.g. labeler or filler) will continue to produce until a sensor on the conveyors warns that the maximum accumulation allowed by the length of the belts has been reached and only then will the upstream machine be stopped. If the packaging machine restarts before reaching the maximum accumulation allowed by the length of the conveyors, the machine upstream will be prevented from stopping upstream and therefore there will be no loss of production.
Regardless, when the packaging machine is restarted, the infeed conveyor will be full of accumulated product. In order that, in the event of a subsequent stop, these conveyors can again perform the function of accumulating products before stopping the upstream machine, they must first be emptied. The packaging machine must therefore have a capacity higher than the nominal capacity of the line (capacity at full production). Generally, an over-capacity of 20% over the nominal line capacity is considered sufficient (capacity at full production).