Injection valve, specially fuel injection valve

The perforated disc manufacturing process involves first preparing two metal foil strips (35), making aperture patterns and auxiliary apertures in them, centering the individual strips and bringing them together and joining them by a jointing process. This produces a strip (29) of perforated disc blanks. The disc blanks are then separated from each other to produce the finished discs (21) in the form of a sandwich of foil layers firmly bonded to each other, with a characteristic aperture geometry in each foil layer.