Investigating the Dimensional and Geometric Accuracy of Laser-Based Powder Bed Fusion of PA2200 (PA12): Experiment Design and Execution

Abstract

Variation management in additive manufacturing (AM) is progressively more important as technologies are implemented in industrial manufacturing systems; hence massive research efforts are focused on the modeling and optimization of process parameters and the effect on final part quality. These efforts are, however, hampered by the very problem they are seeking to solve, as conclusions are weakened by poor validity, reliability, and repeatability. This paper details an elaborate experiment design and the subsequent execution with the aim of making the research data available without loss of validity. Test artifacts were designed and allocated to fixed positions and orientations in a grid pattern within the build chamber to facilitate rigid analysis between different builds and positions in the build chamber. A total of 507 specimens were produced over three builds by laser sintering PA12 before inspection with a coordinate measuring machine. This research demonstrates the inherent variations of laser-based powder bed fusion of polymers (LB-PBF/P) that must be considered in experiment designs to account for noise factors. In particular, the results indicate that the position in the xy-plane has a major influence on the geometric accuracy, while the position in the z-direction appears to be less influential.

Selective Laser Sintering of PA 2200 for Hip Implant Applications: Finite Element Analysis, Process Optimization, Morphological and Mechanical Characterization

“…During the last few years, several studies focused on how to determine the proper SLS process parameters for each material used to produce parts using this technology. To determine the influence of the process parameters (laser power, scanning speed) on the mechanical properties and the density and accuracy of the SLS parts, researchers have tried different approaches to obtain better results regarding the process [ 26 , 27 ]. Another approach is to determine the influence of the different positions and orientations of the parts on the building platform.…”

Estimation and Improvement of the Achievable Tolerance Interval in Material Extrusion Additive Manufacturing through a Multi-State Machine Performance Perspective

“…Observations led to the conclusion that a multi-state perspective should be mandatory when analyzing machine performance in MEX AM processes. Moreover, since previous research studies have pointed out the relevance of the part position with respect to the reference axes in multiple AM processes [17,39], this finding should encourage other practitioners to adopt the multi-state perspective when working with those processes.…”

“…Those works investigating dimensional quality in the AM process are frequently focused on providing a quantification of dimensional quality [8][9][10][11][12], analyzing the influence of different factors upon dimensional accuracy [13][14][15][16][17], or proposing strategies to improve dimensional quality [18][19][20][21]. Boschetto [13] modelled the dimensional deviation of parts manufactured in MEX machines as a function of the deposition angle and layer thickness.…”

“…Goguelin [10] used a test artifact derived from the one proposed by NIST [23] to evaluate the capabilities of a MEX equipment as part of their effort to develop a smart manufacturability assistant. Leirmo [17] proposed a test artifact and an experimental strategy to evaluate dimensional and geometrical quality in PBF. This works paid attention to the differences in dimensional quality related to position and orientation of the part within the working space, but also to the variation related to consecutively manufactured trays.…”