Mechanical Engineering, IIT Kharagpur
Sankha Deb obtained his Ph.D. in Industrial Engineering from Ecole Polytechnique Montreal, Canada and Master’s degree in Manufacturing Process Engineering from IIT Kharagpur. He served as Assistant Professor in the Centre for Soft Computing Research at ISI Kolkata and also in the Department of Mechanical Engineering at IIT Guwahati. He was invited as a Visiting Professor in University of Montreal, Canada in 2008 and 2009. He also served the Industry for a year. Presently he is an Assistant Professor in the Department of Mechanical Engineering at IIT Kharagpur. His research interests are in the areas of Automation and Robotics, Manufacturing Processes, Computer Integrated Manufacturing, and Artificial Intelligence and Soft Computing applications in manufacturing. He co-authored a book on Robotics Technology and Flexible Automation.
Scope and challenges in implementation of robotic additive manufacturing:In this talk, the scope for applications of robotic additive manufacturing, their potential benefits and the main challenges in their implementation will be discussed. One of the factors driving the development of robotic additive manufacturing is the need to build large and complex near-net-shape components more quickly and cost effectively than what is possible with some of the conventional 3 axis additive manufacturing machines. With traditional machines, there are limitations in build volume and orientations. Restricted build volume in conventional additive manufacturing machines due to limitations in their dimensions often tend to limit their use to making smaller end products or smaller components for larger products necessitating subsequent joining/assembly operations. Moreover limitations in orientations of the deposition head limit the applications of conventional machines to make highly complex part geometries. One of the ways to overcome this limitation is to combine FDM type additive manufacturing with industrial robotics technology. A 6 degrees of freedom articulated robot manipulator is very flexible and versatile, characterized by high positional accuracy and repeatability, and typically has a large dexterous workspace, in which it is able to reach with any orientation. The industrial robot’s geometric flexibility and workspace can be used to optimal effect in facilitating manufacture of large and complex print profiles. In order to implement a robotic additive manufacturing system, there are, however, several challenges that need to be overcome. The existing data formats such as STL, or its variants, normally used in 3D printers cannot be used directly. The CAD file needs to be converted to robot printable paths and the robot program for creating the part. Path planning algorithms must be designed to determine the optimal trajectory to be followed by the robot for printing different building materials. The robot TCP speed must be properly coordinated with the material extrusion flow rate from the deposition head. Algorithms to control the robot manipulator should be designed taking into account factors like given material properties, the deposited material thickness, how fast the material hardens, and so on. It is necessary to develop optimal control algorithms to minimize the time to deposit the material and assure the fastest building time for the complete structure. Methods for collision avoidance must also be incorporated in the system. It is further necessary to perform a simulation of the paths to be printed by the robot for visualization and verification for robot reachability and for optimizing the path for TCP speed, extrusion rate, etc. It may be necessary to further analyze the simulated part by exporting to commercial softwares such as FEA to verify its mechanical strength, thermal, electrical and other functional requirements for the simulated process parameters, direction of the building path, etc. and modify the printed path, if required. During execution of the generated path, a camera and sensor based online quality monitoring system can be used to provide real-time feedback to the robot controller so that the building path can be adjusted during the execution to ensure the quality of the build. Robotic additive manufacturing has been recently applied in architectural design applications with demanding surface aesthetics and complex freeform geometric shapes, in construction industry such as making large size, complex formworks for casting concrete, in discrete parts manufacturing industry for manufacture of low volume, high mix complex components of ships, aerospace components, defense components, obsolete replacement parts, repairing worn or out-of-tolerance parts, etc.