Each screw is automatically qualified to allow only screws within specifications to queue. Any rejects are ejected. Oriented screws are stored in a track from which they are guided to an escapement mechanism by gravity and vibration. In blow feeding, screws are blown through a flexible, pressurized tube to the nosepiece of a driver. In other words, the length of the screw should be at least 1.5 times the width of the head.
Shorter screws tend to jam in the feed tubes.
Pointed screws also present some problems and usually can't be blow-fed, because the points can stick into the tube lining. In track feeding, screws travel to the nosepiece of a driver via a steel track. It's an option for screws that can't be fed through a tube. Screws are fed directly to the driver head, or the head can travel to the track to pick and place individual screws. Storage hoppers and feeder bowls are available in a wide variety of styles and sizes to ensure correct feed rates and orientation.