3D Printing of Foods. C. Anandharamakrishnan

3D Printing of Foods - C. Anandharamakrishnan


Скачать книгу
href="#ulink_03d3ba00-4c8f-50dd-bf14-27fe1cb5cbff">Figure 2.1).

       Material extrusion: A polymeric filament is melted using an electrical heat source and the melted liquid is deposited in a layered fashion using a 3D printer through an extrusion mechanism. The deposited material gets fused together upon cooling and attains the desired 3D shape (Shahrubudin et al. 2019). A filament is delivered using a Bowden mechanism for pushing the material filament through a long flexible Teflon tube to the hot end of the printing nozzle. From the nozzle tip, the melted polymer is deposited over the printing platform. Materials such as polylactic acid (PLA) and Acrylonitrile butadiene styrene (ABS) are the most commonly used polymer filaments. A temperature controlling unit is used for varying the temperature according to the melting point of the polymers used. Commercial 3D printers that are based on extrusion technology are referred to as fused deposition modelling (FDM) and fused filament fabrication (FFF). Extrusion‐based technology is comparatively cheaper than other AM processes (Vithani et al. 2019). Although the printing accuracy and precision are good, sometimes post‐polishing is required to enhance the surface smoothness of the 3D printed construct.

       Powder bed fusion: In this AM process, a heat source of either hot air or a high‐energy laser beam is employed to scan the 3D CAD design over the powder bed (Godoi et al. 2019). Due to which the powdered material gets melted and fused according to the shape and design of the 3D CAD model. After completion of the scanning process, the printed material is taken out from the loosened powder of the bed.Figure 2.1 Classification of AM technologies.

       Material jetting: Materials like wax and photo‐polymeric resins are the commonly used materials in this type of AM process. Here, the feed material is deposited in the form of a fine jet either in a continuous fashion or in a drop‐on‐demand (DoD) manner over the printing platform (Holland et al. 2019). The movement of printer arms can be operated based on the 3D model that controls the deposition of the printed layers. The melting point of the material can be precisely controlled through a temperature controller.

       Binder jetting: In the case of binder jetting, the liquid binder is sprayed over the powdered bed. Here, the binder acts as an adhesive that binds the material together. Above which the second layer of powder bed is spread over the printing platform then the liquid binder is sprayed (Sun et al. 2015). Likewise, the process is repeated continuously until the entire 3D model is printed. Commercial 3D printers such as Chef Jet and Chef Jet Pro works based on a binder jetting mechanism.

       Vat polymerization: In this process, a vat of liquid polymer‐based resin mixture is used for constructing a 3D object in a layer‐by‐layer manner. Here, a ultraviolet (UV) light source is used for curing the polymeric resin that results in the hardening of the layer of resin (Xu et al. 2020). After the formation of each layer, the platform moves the fabricated 3D object in a downward direction. Technologies such as SLA, digital light processing (DLP), and liquid crystal printers (LCD) are based on vat polymerization techniques.

       Sheet lamination: In this AM process, a laser beam acts as a knife that cuts the materials like papers, plastics, metals, and ceramics that are suitable for thermal pressing to bind thin layers together into a 3D construct (Ngo et al. 2018). Here, the movement of the laser light is controlled by a computer that moves according to the 3D CAD design. Thus, the 3D construct can be fabricated through laser as a thermal source and the unwanted portions of the material can be easily removed after the completion of the printing process.

       Direct energy deposition/laser metal deposition (LMD): This method employs a high‐energy laser source to melt the material over the processing surface. Thereafter the metal powder is injected into the melted material for the completion of the deposition process (Barro et al. 2020). The movement of the robotic arms is controlled with integration to a computer that moves according to the 2D directions that aids in the construction of a 3D object.


Скачать книгу