Process Division of Soldering Work by Skilled Workers and Cooperative Relationship between Motions and Eye Movements in Making Metal Fittings of Flags

Abstract

The knowledge of the soldering process in producting metal fittings of flags is based only on tacit knowledge, such as knack and intuition. Therefore, it is necessary to make tacit knowledge into explicit knowledge. The purpose of this study was to investigate the process of soldering and the characteristics of human movements during the soldering process. Three-dimensional upper extremity kinematics and eye movement data were collected. The resulting data showed that the process was divided into four stages: “preparation”, “pre-assembly”, “assembly” and “post-treatment”. Motions during the assembly stage suggested that skilled workers controlled the temperature of a soldering bit by checking the speed of solder wettability. In the motions which made the soldering iron come and go between the base material and solder, the metacarpal phalangeal joint of the right forefinger began to move earlier than the eyes, the eyes caught up with the right forefinger, passed it, and reached the solder earlier than the forefinger. In the end, the right forefinger and the eyes returned to the starting position of the cycle.