SELECTIVE SOLIDIFICATION APPARATUS AND METHODS

A selective solidification apparatus includes a build chamber, a build platform lowerable in the build chamber, a wiper for spreading powder material across the build platform to form successive powder layers of a powder bed, an energy beam unit for generating an energy beam for consolidating the powder material, a scanner for directing and focussing the energy beam onto each powder layer and a processor for controlling the scanner. The processor is arranged to control the scanner to scan the energy beam across the powder bed to consolidate powder material either side of the wiper when the wiper is moving across the powder bed and to scan the energy beam across at least one of the powder layers during two or more strokes of the wiper across the powder bed.