Leu-M

Additive manufacturing (AM) is the fabrication of real three-dimensional objects from metals, ceramics, or plastics by adding material, usually as layers. There are several variants of AM; among them material extrusion (ME) is one of the most versatile and widely used. In MEAM, molten or viscous materials are pushed through an orifice and are selectively deposited as strands to form stacked layers and subsequently a three-dimensional object. The commonly used materials for MEAM are thermoplastic polymers and particulate composites; however, recently innovative formulations of highly-filled polymers (HP) with metals or ceramics have also been made available. MEAM with HP is an indirect process, which uses sacrificial polymeric binders to shape metallic and ceramic components. After removing the binder, the powder particles are fused together in a conventional sintering step. In this review the different types of MEAM techniques and relevant industrial approaches for the fabrication of metallic and ceramic components are described. The composition of certain HP binder systems and powders are presented; the methods of compounding and filament making HP are explained; the stages of shaping, debinding, and sintering are discussed; and finally a comparison of the parts produced via MEAM-HP with those produced via other manufacturing techniques is presented.

https://pure.unileoben.ac.at/portal/files/2455715/materials_11_00840.pdf

Additive Manufacturing of Metallic and Ceramic Components by the Material Extrusion of Highly-Filled Polymers: A Review and Future Perspectives

Additive construction: State-of-the-art, challenges and opportunities

Investigation on fish surimi gel as promising food material for 3D printing

The potential to enhance membrane module design with 3D printing technology

Extrusion-based 3D printing of ceramic components

Extrusion based 3D Printing (E3DP) is an Additive Manufacturing (AM) technique that extrudes thermoplastic polymer in order to build up components using a layerwise approach. Hereby, AM typically requires long production times in comparison to mass production processes such as Injection Molding. Failures during the AM process are often only noticed after build completion and frequently lead to part rejection because of dimensional inaccuracy or lack of mechanical performance, resulting in an important loss of time and material. A solution to improve the accuracy and robustness of a manufacturing technology is the integration of sensors to monitor and control process state-variables online. In this way, errors can be rapidly detected and possibly compensated at an early stage. To achieve this, we integrated a modular 2D laser triangulation scanner into an E3DP machine and analyzed feedback signals. A 2D laser triangulation scanner was selected here owing to the very compact size, achievable accuracy and the possibility of capturing geometrical 3D data. Thus, our implemented system is able to provide both quantitative and qualitative information. Also, in this work, first steps towards the development of a quality control loop for E3DP processes are presented and opportunities are discussed.

Process Monitoring of Extrusion Based 3D Printing via Laser Scanning

This paper presents a novel approach of screw extrusion based 3D printing of thermoplastic materials. In contrast to the well-known extrusion based 3D printing technology Fused Deposition ModelingTM based on thermoplastic filament extrusion, granules are used as raw-material in a plastic processing screw, melting the plastic and depositing it at the required locations. The system is designed to overcome some limitations of the filament based process e.g. the need for a thermoplastic filament as feed material, which needs to be produced with a narrow production tolerance with respect to the nozzle diameter to prevent blocking and especially the limited range of commercially available materials which can be processed. The presented system is controlled by an open architecture based CNC-controller, programmed in such a way that it easily can be adapted and extended with new advanced control systems modules, systems to improve product quality.

https://lirias.kuleuven.be/retrieve/242576

A novel approach to additive manufacturing: Screw extrusion 3D-printing

The Aerosol Jet® Printing (AJP) process is a fine feature sub-micron scale deposition process. The paper discusses the optimization of AJP in order to achieve the desired quality of printed silver ink interconnects on polyimide film for embedded electronics applications. A process window containing the parameters which have influence on the quality aspects of the printed tracks is determined to obtain the optimal quality. Important quality aspects in this research include the geometrical and electrical properties of the printed tracks and also the adhesion of these tracks on the substrate. The geometrical properties are determined by optical image processing and profile analysis. To measure the electrical parameters a micro 4-point probe measuring system is used.

Hans Valkenaers

Papers

Extrusion-based 3D printing of ceramic components

Process Monitoring of Extrusion Based 3D Printing via Laser Scanning

A novel approach to additive manufacturing: Screw extrusion 3D-printing

Optimizing aerosol jet® printing of sil-ver interconnections on polyimide film for embedded electronics applications

Process Monitoring of Extrusion Based 3D Printing via Laser Scanning