View abstracts of EWI’s DMC 2017 presentations below. If you’d like to schedule a meeting with an EWI associate at the conference, please complete the form on the right.
Real-time Monitoring of Laser Powder Bed Fusion Additive Manufacturing Process with Array Eddy Current Technology
Evgueni Todorov, Paul Boulware, Kingsley Gaah
The additive manufacturing (AM) process has numerous advantages in comparison to conventional subtractive machining technologies. A laser beam supplies the energy to melt the metal powder and build the component layer-by-layer in a typical laser powder bed fusion (L-PBF) system. Monitoring techniques and non-destructive evaluation (NDE) is relied upon to provide monitoring, material property measurements (e.g., phase composition, microstructure, residual stresses, defects), and geometry layer-by-layer in real time. The lack of adequate NDE techniques for examination before, during, and after AM component fabrication was identified as one of the main current challenges. Small features and discontinuities that may be generated during L-PBF pose unique challenges for process inspection and monitoring.
Array eddy current (AEC) is one of the techniques that has capabilities to directly scan the component without physical contact with the powder and fused layer surfaces at low and high temperatures. The technique can detect discontinuities, surface irregularities, and undesirable metallurgical phase transformations in magnetic and nonmagnetic conductive materials used for laser fusion.
Few technical challenges were addressed in a recent study to enable real-time monitoring with AEC technology. AM specimens were built with process induced and fabricated defects to standardize and test the technique. Electromagnetic properties of AM solid materials and metal powder were measured. An array sensor was developed employing computed modeling. The AEC sensor, data acquisition equipment and software were integrated with L-PBF test bed for performance demonstration. The AEC technology demonstrated excellent sensitivity to surface topography, surface and near-surface subsurface discontinuities and conditions. The data was acquired and imaged in a layer-by-layer sequence demonstrating the real time monitoring capabilities of this new technology.
Prediction and Control of Welding-Induced Distortion on Aluminum Extruded Large Panels
Yu-Ping Yang, John Seaman, Tim Stotler, Mark Schimming
Aluminum extruded panels have been used in shipbuilding, aerospace, and railway industries. Typically, the aluminum extruded panels are produced in large sizes such as 0.5m wide and 18m long. Friction stir welding (FSW) and Gas metal arc welding (GMAW) process are used to join several extruded panels to form a large panel. Longitudinal bowing and angular distortion are the major distortion modes after welding. Numerical models have been used to predict and control distortion. This paper introduces a modeling method and developed distortion control techniques.
Welds to join the extruded panel are long and straight. It is time consuming to analyze the welds using thermal-elastic-plastic analysis method. To reduce the computational time, an efficient numerical modeling method, stretch mapping method, was developed to predict the distortion. The method includes local models and a global model. The local models are analyzed using thermal-elastic-plastic method in which the welding-induced softening in HAZ can be considered in the local model. The model prediction has been validated with experimental results.
Mechanical methods including rolling and rotating extrusion method were modeled to control the welding-induced longitudinal bowing on the aluminum extruded panels. The rollers profile, extrusion tool design, and applied pressure were optimized with numerical models to minimize angular distortion and longitudinal bowing. Numerical results show that both mechanical rolling and the rotation extrusion method can effectively eliminate the distortion induced by welding.
Selecting the Correct Technology for AM Development and Implementation
EWI is enabling broader adoption of 3D printing and additive manufacturing (AM) by industry and the defense supply chain through the development, demonstration, thought leadership, and innovation of critical technologies along the AM process chain. EWI has recently expanded its practice into multiple metal AM fabrication technologies, including laser powder bed fusion and large metal AM with directed energy deposition. This technical expertise, coupled with an extensive equipment suite, can be leveraged to focus on solving broad technical challenges, and developing options and solutions for selecting the correct AM technology and AM material for the application. This presentation will focus on the definition of the elements of the AM process and how to implement them by selecting the correct building, material and post-process technologies for both commercial and defense applications.
EWI is the leading engineering and technology organization in North America dedicated to developing, testing, and implementing advanced manufacturing technologies for industry. By matching our expertise to the needs of our clients, we help manufacturers innovate premium, game-changing solutions that deliver a competitive advantage in the global marketplace.
To learn more about EWI, visit ewi.org.