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1. Fused deposition modelling (FDM)
In this method a thermoplastic filament is used to create 3D print of materials. The filament is heated to its melting point and then extruded, layer by layer from the bottom up using filaments to create 3D object. First, the computer aided design(CAD) files must be converted into .STL file format for FDM printer to understand the architecture of the design. FDM printers use two materials, one as the modelling material and other one to support the material while it is being printed. Both the materials take the form of either filaments or plastic threads during the printing process, which are unrolled from a coil and fed through extrusion nozzles. The heated nozzles melt the filaments and forces them out onto a base or a platform according to the design assigned. Base and the two nozzles are controlled by computer, the nozzles are moved on the building platform(base), according to the design of the object both in horizontal and vertical directions and the base is set to follow them during printing process. The melted plastic sticks and solidifies onto the beneath layer easily and base is lowered after each layer is formed to make the room for the next layers to process. Once the object is printed, the supporting layer is then removed by either soaking in water and detergent solution or just separated using hands if it is thermoplastic. Time required to process each printing depends on the size and complexity of the object. FDM is a low-cost process, faster and simple but it also has drawbacks such as weak mechanical properties of the printed parts, limited amount of thermoplastic materials for the fabrication, poor surface quality etc. Thermoplastic materials can withstand heat, chemicals and mechanical stress which makes them an ideal material for FDM, some of them are acrylonitrile butadiene styrene (ABS), polycarbonate (PC) or polyetherimide (PEI) and support materials used are water-soluble wax thermoplastics such as polyphenylsulfone (PPSF). FDM serves different industries (automotive to consumer goods manufacturing) starting from the product development, prototyping and manufacturing processes.