APPARATUS AND METHODS FOR BUILDING OBJECTS BY SELECTIVE SOLIDIFICATION OF POWDER MATERIAL

摘要

This invention concerns an additive manufacturing machine for building objects by layerwise melting of powder material. The machine comprises a build chamber (101) containing a build platform (102) a powder dispenser (108 109) for depositing the powder material (104) in layers across the build platform (102) a high energy beam for selectively melting powder material (104) in each layer and a control device for controlling a property of the powder material given by build particles in the powder material that are below an upper particle size limit specified for the build. The invention also relates to a method comprising controlling during the build a property such as particle size distribution of the powder material given by build particles in the powder material that are below an upper particle size limit specified for the build. The invention also concerns a method of carrying out successive builds wherein in between the builds particles are added to or removed from the powder material to effect a property of the powder material given by build particles in the powder material that are below an upper particle size limit specified for the builds. The invention in particular concerns adding or removing particles to ensure that a sufficient proportion of micro build particles such as particles below 10 5 or 1�m particles are present in the powder.