Patent ID: 9079248
Filing Date: 2015-07-14
Classification: B22F,B23K,B29C,B33Y,Y02P,Y10T

Abstract:
1. A method for increasing the resolution when forming a three-dimensional article through successive fusion of parts of a powder bed, which parts corresponds to successive cross sections of the three-dimensional article, said method comprising the steps of: providing a vacuum chamber, an electron gun, and a first powder layer on a work table inside said vacuum chamber; directing an electron beam from said electron gun over said work table causing said first powder layer to fuse in selected locations to form a first cross section of said three-dimensional article; providing a second powder layer on said work table; directing the electron beam over said work table causing said second powder layer to fuse in selected locations to form a second cross section of said three-dimensional article, wherein said second layer is bonded to said first layer; and reducing the pressure in the vacuum chamber from a first pressure level to a second pressure level between the providing of said first powder layer and said second powder layer, preheating the powder bed at least partially with said first pressure level, wherein a mean pressure level during the preheating is higher than a mean pressure level during the fusion of the selected locations.