3D printing filament

3D printing filament is created using a process of heating, extruding and cooling plastic to transform nurdles into the finished product. However, unlike a 3D printer, the filament is pulled rather than pushed through the nozzle to create the filament. The diameter of the filament is defined by the process that takes place after the plastic has been heated rather than the diameter of the extruder nozzle. A different force and speed is applied to the filament as it is pulled out of the extruder to define the width of the filament, most commonly 1.75 mm or 2.85 mm diameter. Commercially produced filament In commercial production, the plastic nurdles are always either white or clear. Pigments or other additives are added to the material before it is melted to create coloured filament or filament with special properties, e.g. increased strength or magnetic properties. Before the filament is extruded the nurdles are heated to 80 °C to dry it and reduce water content. The nurdles must be dried, as many thermoplastics are hygroscopic and extrusion of damp plastic causes dimensional flaws (this is also the case when the finished filament is being printed). From there, the nurdles are fed into a single screw extruder where it is heated and extruded into a filament. == Usage ==

The process of transforming 3D printing filament into a 3D model is as follows: • The filament is fed into the FDM 3D printer • The thermoplastic is heated past its glass transition temperature inside the hotend • The filament is extruded and deposited by an extrusion head onto a build platform where it cools • The process is continuous, building up layers to create the model == Materials ==

Among commonly used fused filament fabrication (FFF) materials, acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA) are frequently compared due to differences in thermal and mechanical performance. ABS is typically printed at higher extrusion and bed temperatures and is generally associated with greater impact resistance and higher heat deflection temperature. PLA, by contrast, is commonly processed at lower temperatures and is often noted for stiffness and ease of printing. Reported mechanical properties for both materials vary depending on grade, print orientation, infill structure, and post-processing conditions, and are commonly evaluated using standardized test methods such as ASTM D638, ASTM D256, and ISO 527. File:MELT 3D printer ESA401434.jpg|ESA's Manufacturing of Experimental Layer Technology (MELT) 3D printer can print polyether ether ketone (PEEK) == References ==