Rajeev Dwivedi

Automated torch path planning using polygon subdivision for solid freeform fabrication based on welding

A continuous path is one of the most important requirements for solid freeform fabrication (SFF) based on welding. This paper proposes a method for torch path planning applicable to SFF based on welding with an emphasis on minimum human intervention. The suggested approach describes a method based on the subdivision of a two-dimensional (2-D) polygonal section into a set of monotone polygons to generate a continuous path for material deposition. A two-dimensional contour is subdivided into smaller polygons (subpolygons). The path for each individual subpolygon is generated. The final torch path is obtained by connecting individual paths for all the subpolygons and trimming along the points of intersection of the paths for individual subpolygons. The final path is a closed loop; therefore, any point can be selected as the starting point for material deposition. The proposed method can be used to develop the toolpath for CNC milling.

Process Planning for Multi-Directional Laser-Based Direct Metal Deposition:

Abstract Laser-based direct metal deposition has demonstrated the capability to deposit metal along multiple directions. Suitable control of parameters, namely, the metal-powder feed rate, the traverse speed, and the laser power allow fabrication of a desired shape for a large family of parts. The capability to deposit material along multiple directions eliminates the requirement for support structures. However, accessing the point of deposition and manipulating the direction of deposition require a coordinated control of two kinematical systems; one is related to the deposition platform, whereas the other is related to the deposition head. The identification of the key challenges, a mathematical basis of the process, possible solutions, the subsequent process planning, and experimental results are the subjects of this article.

Field feature detection and morphing-based process planning for fabrication of geometries and composition control for functionally graded materials

Abstract The inherent limitation of most solid freeform fabrication (SFF) is deposition in the form of layers. The set-up rather than the geometry and the material composition of the part becomes more important in the process planning. For a functionally graded material (FGM), the desired composition variation is of infinitesimal order; however, the finite size of the deposition head and the molten pool allows for a quantized volume addition. Such artificial imposition of the process for the desired geometric morphology and the functional gradience of materials limit the accuracy of the part. The frequent variation in the material composition is yet another issue associated with the fabrication of FGMs. The suitability of a field can be attributed to the desired material distribution of a part. Different features of the field are identified and used as the input for process planning. The mathematical morphing of the material gradience allows a smooth variation of the material composition across the geometry of the part during deposition. The paper describes a framework for FGM representation using maxel, process planning, and implementation of the fabrication of geometries, and the control of the material composition. The experimental results for the suggested approach are described.

Additive Manufacturing of Metallic Alloys

Additive processes have gained increasing interest within the discussion of digital fabrication and architecture. In general, architects have encouraged limited implementation of this relatively new mode of production beyond conceptual and representational applications. Few examples exist that pursue the large scale application of this technology and these few cases are primarily focused on utilizing polymer and resin-based materials, ceramics, sand and cementitious materials. While additive manufacturing of metals has reached production scaled efficiency and cost feasibility within medical, aerospace, and aviation manufacturing industries, it has yet to make a significant presence as part of architectural discourse. This chapter presents two additive methods of manufacturing in metals most commonly employed for production and their possible applications within the architectural project. The research presented explores the expanded territory for design freedoms, as well as the higher degree of optimizations unique to this manufacturing process. In addition target areas are defined for implementation within a fully integrated design to manufacturing solution space.