Analysis of printing parameters for metal additive manufactured parts through Direct Ink Writing process

Direct Ink Writing is an Additive Manufacturing process in which a metal ink is continuously extruded to built-up a green metal part. Therefore, a debinding and sintering process is required to obtain the final metal part. This thermal process produces a shrinkage of the green printed part according to several material and printing parameters. In this paper, the influence of printing process planning on the width of printed rods for a copper ink is analyzed by means of a Design of Experiments procedure to optimize the printing and equipment parameters and characterize the shrinkage after the sintering processPeer ReviewedPostprint (published version

Recent Developments in Robocasting of Ceramics and Multimaterial Deposition

Robocasting is a freeform fabrication technique for dense ceramics and composites that is based on layer-wise deposition of highly loaded colloidalslurries. The process is essentially binderless with less than 1% organics and parts can be fabricated, dried, and completely sintered in less than 24 hours. This overview will highlight recent materials developments for structural applications and modelling of slurry flow. Fabrication of preforms for alumina/metal composites will be discussed as well as techniques for multimaterial deposition in both graded structures and discrete placement of fugitive materials.Mechanical Engineerin

Micro computed tomography based finite element models of calcium phosphate scaffolds for bone tissue engineering

Bone is a living tissue that is able to regenerate by itself. However, when severe bone defects occur, the natural regeneration may be impaired. In these cases, bone graft substitutes can be used to induce the natural healing process. As a scaffold for tissue engineering, these bone graft substitutes have to meet specific requirements. Among others, the material must be biocompatible, biodegradable and have a porous structure to allow vascularization, cell migration and formation of new bone. Additionally, the mechanical properties of the scaffold have to resemble the ones of native tissue. The goal of this project is to create a computational model of the calcium phosphate scaffolds that are produced by rapid-prototyping by the Biomaterials, Biomechanics, and Tissue Engineering group at the Technical University of Catalonia. These models are based on finite element analysis and micro computed tomography images in order to consider the actual architecture of the scaffolds. The generated FE-models allow the computation of both local strains, which act as mechanical stimuli on attached cells, as well as the behaviour of the entire scaffold. When considering this information, the scaffold can be optimized for tissue differentiation by tuning both the scaffold architecture and the scaffold material bulk properties.Incomin

Solid Freeform Fabrication of Stainless Steel Using Fab@Home

Metal or ceramic parts can be solid freeform fabricated (SFF) using powdered material processing techniques. A slurry of the powdered material is deposited in a layer-by-layer fashion, and then sintered. We demonstrate this process using a 17-4 PH stainless steel slurry deposited via robotically controlled syringe in the low-cost Fab@Home rapid prototyper. Completed parts had densities as high as 90% volume fraction and tensile strength as high as 35% of the pure solid. Details of the process as well as a number of samples of different geometries are shown.Mechanical Engineerin

Aqueous-Based Extrusion Fabrication of Ceramics on Demand

Aqueous-Based Extrusion Fabrication is an additive manufacturing technique that extrudes ceramic slurries of high solids loading layer by layer for part fabrication. The material reservoir in a previously developed system has been modified to allow for starting and stopping of the extrusion process on demand. Design pros and cons are examined and a comparison between two material reservoir designs is made. Tests are conducted to determine the optimal deposition parameters for starting and stopping the extrudate on demand. The collected test data is used for the development of a deposition strategy that improves material deposition consistency, including reduced material buildup at sharp corners. Example parts are fabricated using the deposition strategy and hardware design.Mechanical Engineerin

Direct Extrusion Freeforming of Ceramic Pastes

Microextrusion freeforming of ceramic lattices from high solids ceramic pastes provides multi-scale hierarchical void structures with the advantages of low shrinkage stress and high sintered density. Alumina lattices were directly fabricated using 80-500 Pm diameter filaments. We report here on the implementation of design and fabrication of these scaffolds for band gap materials and micro fluidic devices.Mechanical Engineerin