Coalescence behaviour of two metallic particles as base mechanism of selective laser sintering

In many R&D places, the process of Selective Laser Sintering (SLS) of high performance metals is subject of investigations. An observation often made in SLS of metals is, that certain materials show a proper bonding behaviour while others tend to form welding pearls (»balling« effect). This paper aims to identify and explain process mechanisms related to this effect. The dominating physical mechanisms are investigated. In addition, it is described which material properties mainly affect the results. The attained insights are transferred to the conditions of SLS in a powder bed layer by process modelling and experimental testing.