Improving solid freeform fabrication by laser-based additive manufacturing

Abstract

Solid freeform fabrication (SFF) methods for metal part building, such as three-dimensional laser cladding, are generally less stable and less repeatable than other rapid prototyping methods. A large number of parameters govern the three-dimensional laser cladding process. These parameters are sensitive to the environmental variations, and they also influence each other. This paper introduces the research work in Research Center for Advanced Manufacturing (RCAM) to improve the performance of its developed three-dimensional laser cladding process: laser-based additive manufacturing (LBAM). Metal powder delivery real-time sensing is studied to achieve a further controllable powder delivery that is the key technology to build a composite material or alloy with a functionally gradient distribution. An opto-electronic sensor is designed to sense the powder delivery rate in real time. The experimental results show that the sensor's output voltage has a good linear relationship with the powder delivery rate. A closed-loop control system is also built for heat input control in the LBAM process, based on infrared image sensing. A camera with a high frame rate (up to 800frame/s) is installed coaxially to the top of the laser—nozzle set-up. A full view of the infrared images of the molten pool can be acquired with a short nozzle—substrate distance in different scanning directions, eliminating the image noise from the metal powder. The closed-loop control results show a great improvement in the geometrical accuracy of the built feature.

Research on molten pool temperature in the process of laser rapid forming

“…After the CAD model of the component was built and sliced electronically into a sequence of layers which defined the regions of the component, a metal component was fabricated directly through laser cladding layer by layer. Many methods with the same basic process of fabricating a component have been developed, but referred to by different names, such as laser engineered net shaping (LENS) (Keicher et al, 1997;Griffith et al, 1999), direct light fabrication (DLF) (Wu and Mei, 2003), Laser-Based Additive Manufacturing (LBAM) (Hu et al, 2002;Hu and Kovacevic, 2003), and so on.…”

Nanotube fountain pen: Towards 3D manufacturing of metallic nanostructures

“…Moreover, directly manufacturing with metals, treated as the final frontier in AM techniques, has achieved remarkable advancement in recent years [7][8][9][10][11][12]. Compared with conventional metal component manufacturing process that usually lasts from weeks to months and lacks dynamics in product design, AM techniques allow the lean manufacturing of the machine parts [5,13,14], indicating a new revolution in the manufacturing industry. The recent progress in the miniaturization of the electromechanical system raises the question of whether the 3D metal printing can be realized at the nanoscale or even atomic level, which is also the core of bottomup nanotechnology defined as molecular manufacturing [15].…”

Low cost integration of additive and subtractive processes for hybrid layered manufacturing

“…Thus, efforts have been going on for extending LM for manufacture of metallic objects. Several techniques like laser-engineered net shaping (LENS), 3D welding, direct metal deposition (DMD), shape deposition manufacturing (SDM), laser based additive manufacturing (LBAM), 3D micro-welding (3DMW) and electron beam melting capable of producing metallic prototypes have been developed by different research groups [2][3][4][5][6][7][8]. Fig.…”