The shrinkage behaviour caused in the direct laser sintering of Cu-based metal powder has been investigated. Shrinkages were observed to be anisotropic and the largest was found in the z (height) direction. The in-plane (x, y) dimensional changes are caused by a combination of three sources: thermal shrinkage, sintering shrinkage, and expansion arising because the metal particles fall during the sintering. A hypothetical two-dimensional model is proposed to explain the expansion phenomenon and the particle size ratio based on this model is also deduced. The experimental results agree well with the hypothesis.
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