Abstract: Variation in hole diameter due to heating effects is minimized even if the shortest machining route is set, and machining quality is improved. A printed circuit board to be scanned by a laser beam is divided into a plurality of scan areas (S1). An order of drilling within the scan area is sorted to obtain a scanning route with the shortest distance (S2). The order of the (N+1)th hole and the (N+2)th hole is swapped in each scanning area if it is determined that the distance between the Nth hole and the (N+1)th hole (here, N is an integer in a range of 1?N?“the maximum number of holes to be drilled in the area”?1?) is less than a predetermined threshold value, and that N+1 is not correspond to the maximum number of holes to be drilled in the scanning area (S3).

Abstract: Variation in hole diameter due to heating effects is minimized even if the shortest machining route is set, and machining quality is improved. A printed circuit board to be scanned by a laser beam is divided into a plurality of scan areas (S1). An order of drilling within the scan area is sorted to obtain a scanning route with the shortest distance (S2). The order of the (N+1)th hole and the (N+2)th hole is swapped in each scanning area if it is determined that the distance between the Nth hole and the (N+1)th hole (here, N is an integer in a range of 1?N?“the maximum number of holes to be drilled in the area”?1?) is less than a predetermined threshold value, and that N+1 is not correspond to the maximum number of holes to be drilled in the scanning area (S3).

Abstract: The method for controlling the withdrawal of the electrode in an NC electric-discharge machine permits a linear withdrawal of the electrode to a forward position at least two blocks preceding the present forward position from the workpiece according to a withdrawal command received by the NC unit and with a high efficiency while a workpiece is being machined with electric discharges made between the electrode and the workpiece with the former being forwarded in relation to the latter according to a control information including positioning commands given to the NC unit for each block.