Post-Processing Effects on Surface Properties of Direct Metal Laser Sintered AlSi10Mg Parts

Abstract

Direct metal laser sintering is a powder bed fusion type additive manufacturing (AM) method. It provides opportunity to create near net shape parts layer-by-layer. Because of poor surface quality post processing operations are required. This paper investigates the effect of surface finishing operations such as abrasive blasting, shot peening and polishing on surface texture properties and green tribological behavior of direct metal laser sintered AlSi10Mg parts. 2D and 3D surface roughness characterization, density and hardness measurements were implemented. Ball-on-disc wear tests were applied under 10 N load with palm oil and soybean oil as green lubricants. Petrol based, commercial machine oil was used for control. The results revealed that post processing operations affected surface texture and tribological properties of the samples. Abrasive blasting increased surface hardness to the 187 HV, while it was measured as 178 HV and 124 HV for shot peening and polishing processes respectively. Average surface roughness Ra, was measured as 18.71 µm for shot blasted surface. This value recorded as 5.39 µm for shot peened and 1.39 µm for polished surfaces. Minimum wear rate was calculated as 3.88 × 10−4 mm3/Nm for shot peened surface with palm oil while maximum was calculated as 7.92 × 10−4 mm3/Nm for polished surface with MO lubrication. Palm oil and soybean oil represented superior lubricating properties than petrol based commercial machine oil for all surfaces. It can be concluded that surface post processing has important effect on texture properties of metal AM parts. Moreover, vegetable oils are promising lubricants for increasing tribological properties of AM surfaces.