Laser Engineered Net Shaping (LENS™) was developed in the mid-1990s at the Sandia National Laboratories. The process, shown in Figure 7.15, uses a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser operating at 500-600 W that is enclosed in an argon gas environment. The laser creates a molten pool into which powdered metal is injected. Parts have been produced from stainless-steel alloys, nickel-based alloys, tool-steel alloys, titanium alloys, and other specialty materials, including composites. As in other additive-manufacturing processes, parts originate from three-dimensional CAD models, and material is built up in layers to create the final part. The significant difference between LENS and other additive processes is that the parts obtain the same density as the metal used to fabricate them. Figure 7.16 shows a tool produced with the LENS process.
FIGURE 7.15 Laser Engineered Net Shaping (LENS™) process schematic. SOURCE: Worldwide Guide to Rapid Prototyping Website, © Copyright Castle Island Co., all rights reserved. Available at http://www.additive3d.com/len_int.htm. Reprinted with permission.