CNC Turning of an Additively Manufactured Complex Profile Ti6Al4V Component Considering the Effect of Layer Orientations

Abstract

Electron beam melting (EBM) is one example of a 3D printing technology that has shown great promise and advantages in the fabrication of medical devices such as dental and orthopedic implants. However, these products require high surface quality control to meet the specifications; thus, post-processing, such as with machining processes, is required to improve surface quality. This paper investigates the influence of two-part orientations of Ti6Al4V EBM parts on the CNC machining (turning) process. The two possible EBM part orientations used in this work are across EBM layers (AL) and parallel to the EBM layer (PL). The effect of the EBM Ti6Al4V part orientations is examined on surface roughness, power consumption, chip morphology, tool flank wear, and surface morphology during the dry turning, while using uncoated carbide tools at different feed rates and cutting speeds. The results showed that the AL orientation had better surface quality control and integrity after machining than PL orientation. Using the same turning parameters, the difference between the roughness (Ra) value for AL (0.36 μm) and PL (0.79 μm) orientations is about 54%. Similarly, the power consumption in AL orientation differs by 19% from the power consumption in PL orientation. The chip thickness ratio has a difference of 23% between AL and PL orientations, and the flank wear shows a 40% difference between AL and PL orientations. It is found that, when EBM components are manufactured along across-layer (AL) orientations, the impact of part orientation during turning is minimized and machined surface integrity is improved.

Multi-Response Optimization of Additively Manufactured Ti6Al4V Component Using Grey Relational Analysis Coupled with Entropy Weights

“…Furthermore, the minor tool feed marks are generated when the milling tool is moved perpendicular to the layers, which achieved a smaller surface roughness, as shown in Figure 6a. All of this is consistent with [19][20][21][22].…”

“…Furthermore, the minor tool feed marks are generated when the milling tool is moved perpendicular to the layers, which achieved a smaller surface roughness, as shown in Figure 6a. All of this is consistent with [19][20][21][22]. The difference in surface roughness among the three directions is because the tool interacts with a single EBM layer while machining along Direction 3 and exerts compressive forces at the EBM layer interface, which causes the bonded layers to rupture, resulting in a high surface roughness.…”

“…Figure 5 demonstrates that the various responses of the machining of the EBM Ti6Al4V component are influenced by changes to the process variables. The selection in faces (Direction 1) and decrease in radial depth of cut increases the GRGs, leading to a decrease in surface roughness and cutting forces which are consistent with [19][20][21]. However, as cutting speed and feed rate decrease from a greater to a lesser value, the relational grades for the output characteristics diminish.…”

“…Some studies have shown that the 3D printing layer orientations have a substantial impact on the final appearance of the additively made components. For example, the impact of the layers' orientations during EBM milling and turning of Ti6Al4V components and milling γ-TiAl components was investigated by [18][19][20]. The researchers discovered that different EBM component orientations during machining can result in different levels of surface roughness, even when using the same machining settings.…”

Optimization of the Effect of Laser Power Bed Fusion 3D Printing during the Milling Process Using Hybrid Artificial Neural Networks with Particle Swarm Optimization and Genetic Algorithms

“…Some studies have shown that the 3D printing layer orientations considerably affect the final visual appearance of the additively manufactured parts. Milling of the Ti6Al4V [38] and γ-TiAl EBM [33] components and turning of the Ti6Al4V EBM [39] components are examples where the effects of layer orientations have been studied and published. It has been found through investigations that the same machining parameters can produce varying degrees of surface roughness depending on the orientation of the EBM component being machined [40].…”