When the melt is ejected from the cut kerf by an assist gas during laser fusion cutting, a fraction of it may adhere to the lower cut edge and form a burr. Adjusting the process parameters to minimize burr formation is a challenging task that becomes more and more difficult as sheet thickness increases. The burr length has significant relevance when the quality of a cut is evaluated, but the underlying mechanisms that control its formation are still not fully understood. In this paper, we present new results of an experimental investigation focused on identifying and characterizing melt ejection regimes. The experiments were conducted on 6 mm thick stainless steel sheets using a disk laser at a power of up to 10 kW. The melt flow exiting the kerf channel and the temporal formation of burr were analyzed using two high-speed cameras. We discuss how the melt ejection regimes depend on the process parameters and how they influence the burr formation. Furthermore, we show that melt ejection forming a compact and stable threefold outflow is a characteristic property of a burr-free cut.
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