Head stroke or feed stroke
The head stroke (also called feed stroke) is needed when the work piece or the automatic screwdriver are not automatically positioned for the screwdriving process (e.g. by a robotic arm or a sliding carrier system). The head stroke describes the path travelled by the feed head to the work piece in order to screw in the fastening element: The fastening element is blown by air into the feed head, which then travels with the fastening element to the work piece.
Subsequently, the bit moves into position and screws the fastening element into the work piece. The feed head then returns to its start position and the bit is retracted. This process ensures that no incorrectly inserted fastening element (e.g. due to faulty boring or defective thread) will remain in the nose piece and have to be removed manually. The automatic screwdriving process continues without interruption; as a rule, the faulty work piece will be automatically ejected.