This study examines the influence of deposition layer thickness on the mechanical properties of printed ABS material when manufacturing using Fused Filament Fabrication (FFF). Tensile and compression testing was performed to ASTM standards on samples printed with layer thickness between 0.2mm and 0.8mm. Results found material strength and stiffness was greatest using smaller layer thicknesses, compared with larger layer thicknesses e.g. (0.2) = 31.5 MPa, (0.2) = 38.2 MPa, compared with (0.8) = 23.0 MPa, (0.8) =31.0 MPa. The recorded changes in mechanical properties are explained by mechanisms relating to manufacturing residual porosity, the number of deposited layers promoting interlayer bonding strength, and the extrusion process resulting in material shear hardening. Findings have implications on the ability to reduce the overall part print time using a method of increased material deposition, and may have profound implications on comparative part integrity when utilising large volume deposition printing formats with unmodified ABS polymer. The findings from this study also highlight the need for current mechanical testing standards to accommodate appropriate guidelines for the testing of 3D printed material, given the wide variance of measured tensile and compression properties based on layer thickness and printed geometry.

Machinability tests were conducted on duplex alloys SAF 2205 and SAF 2507, while employing austenite stainless steel 316L as a benchmark during drilling. Tool wear, cutting forces and machined surface finish were compared and analysed under similar machining conditions. Both duplex alloys displayed poorer machinability responses, with 2507 being worst. Abrasion and adhesion are the most common wears appeared on the flank and rake faces. Adhesion wear being the most severe on the flank face, is seen to be triggered by built-up edge formation. Duplex alloys 2507 and 2205 both show a higher response to built-up edge formation. Flute damage on the drill tools found during drilling of both duplex alloys can cause tool failure. Higher machining force and worse surface finish were found for second generation duplex (2507).

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This research work presents a machinability study between wrought grade titanium and selective laser melted (SLM) titanium Ti6Al-4V in a face turning operation, machined at cutting speeds between 60 and 180 m/min. Machinability characteristics such as tool wear, cutting forces, and machined surface quality were investigated. Coating delamination, adhesion, abrasion, attrition, and chipping wear mechanisms were dominant during machining of SLM Ti-6Al-4V. Maximum flank wear was found higher in machining SLM Ti-6Al-4V compared to wrought Ti-6Al-4V at all speeds. It was also found that high machining speeds lead to catastrophic failure of the cutting tool during machining of SLM Ti-6Al-4V. Cutting force was higher in machining SLM Ti-6Al-4V as compared to wrought Ti-6Al-4V for all cutting speeds due to its higher strength and hardness. Surface finish improved with the cutting speed despite the high tool wear observed at high machining speeds. Overall, machinability of SLM Ti-6Al-4V was found poor as compared to the wrought alloy.

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