The Dimensional Accuracy of Thin-Walled Parts Manufactured by Laser-Powder Bed Fusion Process

Abstract

Laser-Powder Bed Fusion brings new possibilities for the design of parts, e.g., cutter shafts with integrated cooling channels close to the contour. However, there are new challenges to dimensional accuracy in the production of thin-walled components, e.g., heat exchangers. High degrees of dimensional accuracy are necessary for the production of functional components. The aim is to already achieve these during the process, to reduce post-processing costs and time. In this work, thin-walled ring specimens of H13 tool steel are produced and used for the analysis of dimensional accuracy and residual stresses. Two different scanning strategies were evaluated. One is a stripe scan strategy, which was automatically generated and provided by the machine manufacturer, and a (manually designed) sectional scan strategy. The ring segment strategy is designed by manually segmenting the geometry, which results in a longer preparation time. The samples were printed in different diameters and analyzed with respect to the degree of accuracy and residual stresses. The dimensional accuracy of ring specimens could be improved by up to 81% with the introduced sectional strategy compared to the standard approach.

Laser powder bed fusion of the steels used in the plastic injection mould industry: a review of the influence of processing parameters on the final properties

“…This issue can, potentially, be solved by elevating the temperature of the platform during the fabrication, hence reducing temperature gradients during the process [72,73]. The supports to connect the platform to the parts are extremely important to ensure a good heat transfer during the process, to avoid localized heat accumulation, and to prevent defects in the parts produced [74]. Finally, the laser scan strategy is another important parameter of LPBF.…”

“…As for 420 stainless steel, almost all the studies used spherical particles (average diameter sizes from 15 to 63 µm) for the production of cube parts [57,66,69,[95][96][97][98][99][100][101][102][103][104][105][106][107][108][109][110][111][112]. The energy density varied from 17.4 to 760 J/mm 3 , with the most reported values of 67, 80, 100, and 300 J/mm 3 [15,57,66,69,74,96,97,100,103,[109][110][111][112][113][114][115][116]. In most studies the layer thickness was 30 µm [15,57,74,101,108,109,[112][113][114]…”

“…The energy density varied from 17.4 to 760 J/mm 3 , with the most reported values of 67, 80, 100, and 300 J/mm 3 [15,57,66,69,74,96,97,100,103,[109][110][111][112][113][114][115][116]. In most studies the layer thickness was 30 µm [15,57,74,101,108,109,[112][113][114][115][116][117]. Jung et al [99] used a dual scan approach, with a layer thickness of 250 µm.…”

“…Jung et al [99] used a dual scan approach, with a layer thickness of 250 µm. In regard to laser power, a wide range of values were reported (90 to 1,000 W), with the value of 175 W being the most preferred [15,57,74,109,112,[114][115][116]118]. This value is higher than that used in most cases for 420 stainless steel.…”

Effects of process parameters and geometry on dimensional accuracy and surface quality of thin strut heart valve frames manufactured by laser powder bed fusion

“…Dimensional accuracy is another critical issue to consider in the LPBF of fine-sized parts. Tomas et al [18] investigated the dimensional accuracy of thin wall, circular H13 tool steel parts (1 mm thickness, diameters of 25-85 mm) with stripe and sectional scan strategies. All the parts were oversized with a dimensional error ranging from 0.1 mm to 0.5 mm compared to the nominal diameters.…”