Design for Metallic Additive Manufacturing Machine with Capability for Certify as You build

Although, additive Manufacturing ( AM) has been hailed as the third industrial revolution by The Economist magazine [April-2012], the first patent on Stereo-lithography was awarded in 1986. An enabling technology which can build, repair or reconfigure components layer by layer or even pixel by pixel with appropriate materials to match the performance will enhance the productivity thus reduce energy consumption. Innovative product such a metallic composites with negative co-efficient of thermal expansion has already been demonstrated. The capability to form a three-dimensional object directly form digital data reduces many intermediate steps in manufacturing and, therefore, potentially an attractive and economic fabrication method. This is very suitable for low volume manufacturing. The major challenge for design of additive manufacturing machine is on line Quality assurance due to its application in low volume manufacturing. Statistical quality control is not applicable due to low volume. Moreover, any new innovative product has to go thorough a long process of certification before adaptation, especially for Aerospace and medical device industry. This paper presents the design methodology for Smart Metallic Additive Manufacturing System (s-AMS). In-situ optical diagnostics and its capability to integrate with the process control is a prudent alternative. The two main groups of AM are powder bed (e.g. Laser Sintering) and pneumatically delivered powder (e.g. Direct Metal Deposition [DMD]) to fabricate components. DMD enables one to deposit different material at different pixels with a given height directly from a CAD drawing. The feed back loop also controls the thermal cycle. New optical Sensors are being developed to control product health and geometry using imaging, cooling rate by monitoring temperature, microstructure and composition using optical spectra. Ultimately these sensors will enable one to Certify as you Build. Recently the author and his group have developed a technique to analyze the plasma spectra to predict the solid-state phase transformation, which opens up the new horizon for the materials processing and manufacturing. Flexibility of the process is enormous and essentially it is an enabling technology to materialize many a design. Conceptually one can seat in Houston and fabricate in Haifa. This paper discusses the in-situ diagnostic methods and its integration the design of the machine. (C) 2015 The Authors. Published by Elsevier B. V.