Investigation on Precision of Laser Powder Bed Fusion Process Using Statistical Process Control

Laser Powder Bed Fusion (L-PBF) process is one of the cutting-edge technologies in the field of Additive Manufacturing (AM). L-PBF offers the advantage of manufacturing complex geometries in reduced time; however, its use for high precision applications and the achievement of good dimensional accuracy are still challenging. The aim of the current study is to investigate the precision of L-PBF process using Statistical Process Control (SPC) and assess the capability of the manufacturing process. A benchmark artefact was designed and fabricated by L-PBF process to evaluate the dimensional accuracy. The artefact consists of slender cylinders with variable internal diameters of 0.8 mm, 1 mm and 1.5 mm as a function of different wall thicknesses and inclinations of 90°, 60°, 45° and 0°. The material used for manufacturing the artefact was Inconel 718. Investigation on the impact of part positioning on the base plate and the impact of part orientation on dimensional accuracy were studied. To verify the process repeatability and part reproducibility using statistical process control, all the cylinders have been positioned in five different locations on the base plate. Impact of re-coater collision on the parts has been investigated by fabricating the parts with hard and soft re-coaters. The results presented in this work explain a design approach to fabricate slender parts successfully and the deviation in dimensional accuracy of cylinders from the actual design intent, involving the internal and external diameters of the cylinders, to verify the consistency of the process