Tailored Scan Strategies For Improved Dimensional Accuracy And Surface Roughness Of Cooling Channels In Laser Powder Bed Fusion

Manufacturing of tools and molds with efficient conformal cooling has become one of the most important applications of laser-based powder bed fusion of metals. However, in real operation, problems such as corrosion, fouling and high flow resistance jeopardize the long-term cooling performance. These aspects are linked to the inner surface roughness resulting from the powder based additive manufacturing process. Warping, dross formation and overheating are phenomena that typically occur at the unsupported upper areas of the channels.Tailored scan strategies have been investigated regarding their impact on the manufacturability and part quality of channels with diameters ranging from 1 to 7 mm. Image processing of cross sections was performed to quantify dimensional accuracy and roughness profiles. With increasing diameter, an orthogonal alignment of the scan vectors to the overhanging edges shows a positive influence on the dimensional accuracy and surface roughness compared to a parallel and alternating alignment.