Selective laser solidification apparatus and method

A method of controlling an additive manufacturing process, in which a laser beam is used to selectively melt powder of a powder bed to form, in the presence of a gas flow across the powder bed, an object layer-by-layer, the method comprising:

• determining at least one lane across the powder bed in a direction debris is carried by the gas flow;
• and
• controlling the laser beam to melt the powder of the powder bed outside the at least one lane.

A method of controlling an additive manufacturing process, in which a laser beam is used to selectively melt powder of a powder bed to form, in the presence of gas-borne debris generated by the melting of the powder, an object layer-by-layer, the method comprising:

• ordering melting of areas of the powder to control creation of the gas-borne debris such that scanning of the laser beam across the layer does not interact with the gas-borne debris,
• wherein a downwind area, which is (i) downwind of an upwind area and (ii) outside of a zone of gas-borne debris created by melting the upwind area, is melted after melting the upwind area.