Machinery's Handbook, 31st Edition
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ADDITIVE MANUFACTURING WORKFLOW Table 8. Additive Manufacturing Workflow
Powder Bed Fusion (PBF).— Powder bed fusion is ASTM’s term for an additive manu- facturing process in which a point heat source selectively fuses or melts a region of a powder bed. There are two types of PBF technology; each system has advantages and disadvantages compared to the other. Selective Laser Melting (SLM): In the original ASTM Standard F2792, laser sintering AM is defined as a “powder bed fusion process used to produce objects from powdered materials using one or more lasers to selectively fuse or melt particles at the surface, layer by layer, in an enclosed chamber.” The definition goes further to note that “sin - tering” is a historical term and a misnomer, because the process involves full or par- tial melting, as opposed to traditional powdered metal sintering, in which a compacted powder part is heated below its melting point. For this reason, the term selective laser melting is widely used and accurately describes the process. It is similar in principle to selective laser sintering (SLS) described in Additive Manufacturing Plastics on page 611. The SLM system is an important technical innovation, with roots dating to the 1990s. Early systems used a gas or disk laser and processed primarily low-melting- point bronze powder, mixed with stainless steel powder that had a higher melting point. Today, SLM systems use a fiber laser as the fusion heat source to completely melt the powder. Typical laser power in metal SLM systems ranges between 100 and 1000 W, and some modern systems have two or four lasers operating simultaneously to increase production rates. Of the metal AM processes, SLM is one of the most widely used.
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