Development of Edge-Preparing Plasma Arc Cutting (EPPAC) System

Edge-Preparing Plasma Arc Cutting (EPPAC) systems have been developed. Top edges of kerfs generated by these systems have bevel angle of θ >155°, which is equal to or larger than that of 3-pass grinding edges. Cutting qualities except for melting of cut shoulder equivalent to or better than those of kerfs generated by conventional machines, and there is no slowdown on the cutting speed. The developed systems are tested under the practical condition in Japanese shipyards, and it has been demonstrated that there is no special problem in workplace safety, and kerfs which satisfy the requirements specification can be generated with high stability. The lower bound of 95% confidence interval of edge retention ratio (ERR) of EPPAC kerfs is about the same as that of 3-pass grinding edges. This means that the top edge shape of kerfs generated by developed EPPAC systems conforms to IMO/PSPC, and there is no need of additional hand grinding. We can cut the man-hours for edge treatment in half by using developed EPPAC systems.