Feasibility of Producing Core-Shell Filaments through Fused Filament Fabrication

Fused filament fabrication is a technology of additive manufacturing that uses molten thermoplastics for building parts. Due to the convenient shape of the raw material, a simple filament, the market offers a great variety of materials from simple to blends of compatible materials. However, finding a material with the desired properties can be difficult. Making it in-house or using a material manufacturer can be costly and time-consuming, especially when the optimum blend ratios are unknown or new design perspectives are tested. This paper presents an accessible method of producing core-shell filaments using material extrusion 3D printing. The printed filaments are characterised by a polycarbonate (PC) core and acryl butadiene styrene (ABS) shell with three material ratios. Their performance was investigated through printed samples. Additionally, the material mixing degree was studied by varying the extrusion temperature, nozzle feeding geometry, and layer thickness. The influence of all four factors was evaluated using a graphical representation of the main effects. The results showed that a core-shell filament can be processed using a 3D printer with a dual extrusion configuration and that the mechanical properties of the samples can be improved by varying the PC–ABS ratio. This research provides an accessible method for developing new hybrid filaments with a predesigned structure using a 3D printer.

A comparative study between weldability of polycarbonate and nylon-6 using different pin geometries in friction stir welding

The solid state friction stir welding (FSW) has been recently the choice for joining of thermoplastics. The present work aims at analyzing the implementation of FSW in joining of different thermoplastics namely, polycarbonate and nylon-6 sheets using varying tool pin profiles, cylindrical, square, and triangular. The novelty of this article is the comparative assessment that has been made on the weldability of these two thermoplastics by determining the mechanical properties of the joint along with real-time acquired force, torque, and temperature signals. Higher axial force with reduced torque has been observed for nylon-6 as compared to polycarbonate. The joint efficiency was found to be maximum (>50%) at tool rotational speed 1800 rpm and welding speed 20 mm/min using square tool pin profile for each of the base materials. Minor undercut defect along with improved material mixing has been seen during the tool stirring process. The study would be helpful for the industries to choose thermoplastics based on their applications.

Direktcompoundierung für die Medizintechnik/Development of direct compounding

In diesem Beitrag wird die Entwicklung des Direktcompoundierens (Direktspritzguss und Direktextrusion) als Alternative zum konventionellen zweistufigen Prozess, der aus dem Compoundieren und anschließender Verarbeitung in der Kunststofftechnik besteht, vorgestellt. Bei der Direktcompoundierung werden Mischen, Schmelzen und Formen zu fertigen Produkten kombiniert. Ein Vorteil hierbei ist die Möglichkeit von Produktindividualisierungen durch die direkte Einflussnahme und Anpassung der Materialrezeptur.   The content of this article is the development of direct compounding (direct injection molding and direct extrusion) as an alternative to the conventional two-stage process, which consists of compounding and subsequent processing in the polymer technology. Direct compounding comprises material mixing, melting and direct molding to form finished products in one step. One advantage here is the possibility of product customization through direct influence and adaptation of the material recipe.

Mixing Chamber for Preparation of Nanorefrigerant

The last decade has seen the rapid advancement of nanofluid in several ways. Nanofluid based on the refrigerant have been introduced as nanorefrigerant in recent years due to their significant effects on the efficiency of heat transfer. Previous studies showed some limitation in ways of dispersing nanoparticles into refrigerant. Hence, a new idea of adding nanoparticles into refrigerant has been presented. A mixing chamber has been designed to mix nanoparticles into high pressure refrigerant. The mixing chamber design is drawn with five different wall thickness which are 2 mm, 4 mm, 6 mm, 8 mm and 10 mm to investigate the sturdiest design that can withstand high pressure. Static structural analysis is performed to all designs with different wall thickness on SolidWorks Simulation. The maximum values of von Misses stress and displacement has been presented in this paper. Validation of the results are made by comparing the maximum values of von Mises stress with yield strength of the material. Mixing chamber with wall thickness of 10 mm showed the best results.