Laser engineered net shaping

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Laser engineered net shaping or LENS is a technology developed by Sandia National Laboratories for fabricating metal parts directly from a computer-aided design (CAD) solid model by using a metal powder injected into a molten pool created by a focused, high-powered laser beam.

A high power laser is used to melt metal powder supplied coaxially to the focus of the laser beam through a deposition head. The laser beam typically travels through the center of the head and is focused to a small spot by one or more lenses. The X-Y table is moved in raster fashion to fabricate each layer of the object. The head is moved up vertically as each layer is completed. Metal powders are delivered and distributed around the circumference of the head either by gravity, or by using a pressurized carrier gas. An inert shroud gas is often used to shield the melt pool from atmospheric oxygen for better control of properties, and to promote layer to layer adhesion by providing better surface wetting.

This process is similar to other 3D fabrication technologies in its approach in that it forms a solid component by the layer additive method. The LENS process is unique since it can go from raw material directly to metal parts, in many cases, without any secondary operations. It can produce parts in a wide range of alloys, including titanium, stainless steel, aluminum, and other specialty materials; as well as composite and functionally graded materials. Primary applications for LENS technology include repair & overhaul, rapid prototyping, rapid manufacturing, and limited run manufacturing for aerospace, defense, and medical markets. Microscopy studies show the LENS parts to be fully dense with no compositional degradation. Mechanical testing reveals outstanding as-fabricated mechanical properties.

The process can also make "near" net shape parts when it's not possible to make an item to exact specifications. In these cases post production light machining, surface finishing, or heat treatment may be applied to achieve end compliance.

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This article has been tagged since June 2007.