The indirect selective laser sintering of aluminium process was investigated in order to characterise the shrinkage of indirect SLS aluminium parts during the various stages of production. Initially nine parts were built in a 3 X 3 grid. The base powder used in this work consisted of pre-alloyed AA6061 powder that was mixed with 2% Mg, 1% Sn and 3%(7.5%) nylon. Standard scale parts were measured using a Giddings and Lewis co-ordinate measuring machine in both the green and infiltrated condition. The experiments conducted show that most accuracy is lost during the furnace cycle and that the greatest loss of accuracy occurred in the Z dimension. Additionally the position of parts within the part bed in both X, Y and Z is shown to influence accuracy, with smaller parts being built closer to the edge of the bed later in the build. This has been attributed to temperature variations within the build bed as well as a gradual, overall warming of build volume and continued sintering as the build progresses. Thus, it appears that growth in all directions is a major contributor to the initial variation in dimensions. Nonetheless, the dimensional accuracy has been calculated to be similar to that for the investment casting process suggesting the potential to use indirect SLS of aluminium for applications that currently use investment casting, especially where geometries are complex and production volumes are low.
Process repeatability and sources of error in indirect SLS of aluminium
Rapid Prototyping Journal ; 14 , 2 ; 108-113
2008
6 Seiten, 7 Bilder, 2 Tabellen, 7 Quellen
Article (Journal)
English
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