Method of determining process parameters for laser powder bed fusion additive manufacturing

A computer-implemented method for controlling a device arranged to perform a laser powder bed fusion, LPBF, additive manufacturing process, the method comprising determining a set of control parameters to control said device for additive manufacturing by:

• providing a set of thermophysical properties of the powder to be used, a set of parameters specific to said device including at least a laser spot size, and a target layer thickness for a layer to be produced in the LPBF process;
• modelling a laser melt pool as a half ellipsoid shape with melt pool depth d and melt pool width w, wherein consecutive laser passes have a separation x, and determining a value for the separation x which yields a maximum amount of added net molten material in a single laser pass;
• expressing said determined value of the separation x as a function of melt pool depth;
• solving the separation expression for laser power and scan speed subject to the target layer thickness and the Plateau-Rayleigh criterion, by deriving from said set of parameters specific to said device a plurality of pairs of laser power and scan speed, obtaining for each pair the melt pool width w, melt pool length l and melt pool aspect ratio R from the melt pool model comprising said set of parameters including said laser spot size and said thermophysical properties, calculating d as d=R·w, and finding a pair of laser power and scan speed values that satisfies the Plateau-Rayleigh criterion and said target layer thickness;
• deriving from the obtained values for laser power and scan speed said set of control parameters to control said device.