This automatic feeder allows the line to work almost non-stop, greatly reducing the empty frames inside the oven. The feeding unit intervenes at a given scheduled time, taking over the wooden pallet, thus continuing to scroll the remaining sheets. This allows the operator to proceed with the preparation of the next pack of sheets on the platform of the sheet inserter made previously free. After processing the last sheet, the feeder leaves automatically the sheet inserter to load a new stack of sheets and to restart production immediately. This feeding unit can be: standard (vertical), bridge or cantilever type.