Method and equipment for testing the quality of production in a tobacco product manufacturing line

The quality of cigarettes advancing along a manufacturing line is tested by a method that includes the steps of checking key characteristics of the cigarettes as they pass through testing units placed at given points along the line, so as to obtain first signals reflecting the quality of the tested characteristics presented by each cigarette, inhibiting the operation of reject devices to prevent defective cigarettes from being ejected, then taking up a given number of tested cigarettes as samples at the outfeed stage of the line, including defective cigarettes, and directing them into an auxiliary off-line testing unit by which they are checked a second time so as to obtain a second signal reflecting the quality of the same characteristics; the method also includes the step of sending a signal to the in-line testing units so that, if the first signals differ from the second signals, the in-line units can be recalibrated, thereby optimizing the quality of the cigarettes produced on a given manufacturing line or in a particular batch, and minimizing rejects.