A process is provided for making reduced fat, low fat or no-fat graham-based crackers and flour for the production thereof. A generator which is needed for generating the oscillating airflow comprises a movable surface which is integrated in a wall of a housing having an internal space and at least one opening for allowing air to flow to and from the internal space. 5% by mass of Al and an anticorrosive layer formed on a surface of the substrate by chemical conversion treatment.