On the surface integrity of additive manufactured and post-processed AlSi10Mg parts

Debajyoti Bhaduri, Pavel Penchev, Stefan Dimov, Khamis Essa, Luke N. Carter, Catalin I. Pruncu, Jun Jiang, Daniele Pullini
2020 Procedia CIRP  
In today's business environment, the trend towards more product variety and customization is unbroken. Due to this development, the need of agile and reconfigurable production systems emerged to cope with various products and product families. To design and optimize production systems as well as to choose the optimal product matches, product analysis methods are needed. Indeed, most of the known methods aim to analyze a product or one product family on the physical level. Different product
more » ... ferent product families, however, may differ largely in terms of the number and nature of components. This fact impedes an efficient comparison and choice of appropriate product family combinations for the production system. A new methodology is proposed to analyze existing products in view of their functional and physical architecture. The aim is to cluster these products in new assembly oriented product families for the optimization of existing assembly lines and the creation of future reconfigurable assembly systems. Based on Datum Flow Chain, the physical structure of the products is analyzed. Functional subassemblies are identified, and a functional analysis is performed. Moreover, a hybrid functional and physical architecture graph (HyFPAG) is the output which depicts the similarity between product families by providing design support to both, production system planners and product designers. An illustrative example of a nail-clipper is used to explain the proposed methodology. An industrial case study on two product families of steering columns of thyssenkrupp Presta France is then carried out to give a first industrial evaluation of the proposed approach. Abstract The research centres on the evaluation of surface integrity of AlSi10Mg parts produced via laser-based powder bed fusion (LPBF) process, followed by vibratory surface finishing. The alloy is chosen for its applications in lightweight components used in electronic packaging, automotive and aerospace sectors. Initial experiments involve optimisation of key LPBF process parameters by analysing the surface roughness and density data of the built parts. A Taguchi L18 orthogonal array is used for the optmisation trials with variations in the laser power (P), beam scanning speed (v), hatch spacing (H) and island size (I). Latter experimental phase deals with microhardness and microstructure assessment of heat treated LPBF specimens that are produced using the optimised LPBF parameters, i.e. P: 250 W, v: 1500 mm/s, H: 75 µm and I: 2 mm. Microhardnesses of the annealed samples reduce by ~12% with respect to the as-built parts and the values remain almost unchanged from the annealed state following solution treatment and ageing. The fish-scale like melt-pools observed on the unheat treated samples begin to fade off in the annealed specimens and completely disappear after solution treatment and ageing, with silicon particles dispersed all over the aluminium matrix. The final experimental phase involves vibratory surface finishing of the as-built LPBF parts using a vibrating ceramic media mixed with different acid and amine based liquid compounds for 1-6 hours, followed by vibrating in a maize based media for another 1-6 hours. The process aids in reducing the parts' roughness, Sa by ~35-70%, however the effect is more prominent when using the ceramic media. Abstract The research centres on the evaluation of surface integrity of AlSi10Mg parts produced via laser-based powder bed fusion (LPBF) process, followed by vibratory surface finishing. The alloy is chosen for its applications in lightweight components used in electronic packaging, automotive and aerospace sectors. Initial experiments involve optimisation of key LPBF process parameters by analysing the surface roughness and density data of the built parts. A Taguchi L18 orthogonal array is used for the optmisation trials with variations in the laser power (P), beam scanning speed (v), hatch spacing (H) and island size (I). Latter experimental phase deals with microhardness and microstructure assessment of heat treated LPBF specimens that are produced using the optimised LPBF parameters, i.e. P: 250 W, v: 1500 mm/s, H: 75 µm and I: 2 mm. Microhardnesses of the annealed samples reduce by ~12% with respect to the as-built parts and the values remain almost unchanged from the annealed state following solution treatment and ageing. The fish-scale like melt-pools observed on the unheat treated samples begin to fade off in the annealed specimens and completely disappear after solution treatment and ageing, with silicon particles dispersed all over the aluminium matrix. The final experimental phase involves vibratory surface finishing of the as-built LPBF parts using a vibrating ceramic media mixed with different acid and amine based liquid compounds for 1-6 hours, followed by vibrating in a maize based media for another 1-6 hours. The process aids in reducing the parts' roughness, Sa by ~35-70%, however the effect is more prominent when using the ceramic media.
doi:10.1016/j.procir.2020.02.093 fatcat:zmnfykjlafhh5fe6dpjefeihce