Method and device for producing three-dimensional objects

A computer program product comprising at least one non-transitory computer-readable storage medium having computer-readable program code portions embodied therein, the computer-readable program code portions comprising one or more executable portions configured for:

• scanning a powder layer area by scanning a first electron beam in a first region along a first series of paths and by scanning a second electron beam in a second region along a second series of paths distributed over the powder layer area, wherein consecutively scanned paths in each of the first and second series of paths are separated by, at least, a security distance, said security distance being adapted to prevent a pre-heated powder in said first and second regions respectively to exceed a maximum charge density, above which discharge will occur, from said consecutively scanned paths;
• and
• synchronizing a movement of said first and second electron beams when simultaneously preheating powdery material within said first and second regions respectively, so that said first and second electron beams are always separated from each other by at least a minimum security distance, said minimum security distance being adapted to prevent a sum of a charge distribution in the powdery material from reaching a critical point at which powder particles start to repel each other.