Additive layer manufacturing method for producing a three-dimensional object and three-dimensional object

An additive layer manufacturing method for producing a three-dimensional object, comprising:

• applying layers of a powder material one on top of another to a carrier in a direction of gravity such that each layer of powder material constitutes an entire length of the elongate portion;
• irradiating each layer of powder material before a following layer is applied with a laser beam or a particle beam selectively only in areas of the layer which correspond to the three-dimensional object to be produced, wherein irradiation takes place such that the powder material in the corresponding areas is locally melted or sintered;
• forming an elongate portion of the three-dimensional object, which has an outer surface and in a direction of extension has a first end and an opposite second end and several longitudinal channels, which extend, separately from one another, in each case in the direction of extension of the elongate portion from the first to the second end, so that a fluid can be conveyed through each of the longitudinal channels from the first end to the second end;
• and
• constructing the elongate portion such that:
• the longitudinal channels extend, at least along a part of their length, at an angle of more than 50° to the direction of gravity;
• and
• along the entire length of the elongate portion the longitudinal channels are formed and arranged such that, in cross section perpendicular to the direction of extension of the elongate portion, for each of the longitudinal channels, a minimum distance to the outer surface of the elongate portion is not smaller than a minimum distance to all adjacent longitudinal channels.