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Fabrication of Shape Memory Polymers
Published in Subhash Singh, Dinesh Kumar, Fabrication and Machining of Advanced Materials and Composites, 2023
S.V. Satya Prasad, P. Prasanna Kumari
Bottom-up extrusion is done in the FDM in which the material is fed via roller is melted within a liquefier (temperature > Tm) and extruded through a nozzle in the form of strands, over a platform that is pre-heated. This happens with the help of a static filament which can be lowered once material deposition is complete. After which, the next layer will get deposited as desired via mobile extruder sustained at low temperatures, whose head is capable of moving along the horizontal plane. The platform is capable of moving along the perpendicular axis of the horizontal plane. The single filament acts like a piston to push out the material in molten form to be deposited as extremely thin successive layers in a set location. FDM is advantageous compared to SLA since layer solidification doesn’t occur due to the energy from a photon (UV radiation) [27]. For the polymer materials like polylactic acid (PLA) and polyethylene (PE), PTFE (polytetrafluoroethylene) as well as Cu are utilized in calibrating nozzle and for sealing heat. But in case of polymers with high temperatures like Acrylonitrile Butadiene Styrene (ABS), Al is employed in a calibrating nozzle. Usually the FDM technique is ideal for thermoplastics and its composites like PLA, ABS, polyurethane (PU), PC (polycarbonate), and polymers filled with glass. Among these, PLA is mainly 3-D printed using the FDM process due to its lower temperatures of printing, easy usage, lower warping w.r.t other polymers, and its lower levels of toxicity in comparison to ABS.
Additive Manufacturing of Polymers for Biomedical Applications
Published in Atul Babbar, Ankit Sharma, Vivek Jain, Dheeraj Gupta, Additive Manufacturing Processes in Biomedical Engineering, 2023
These materials are softened by heating so they can be moldable, and on cooling, they solidify to provide the given shape. The process can be repeated since the long-chain polymers are held by a weak Van der Waals force. Examples of thermoplastic polymers are polyethylene, polystyrene, nylons, polycarbonate, polyether imide and others. Traditional processes, such as injection molding and material extrusion, are used to produce thermoplastic parts. Three-dimensional printing technology, such as FDM and SLS, can create complex parts by using thermoplastic polymer. Commonly used thermoplastic polymers in FDM are acrylonitrile butadiene styrene, polylactide, polyamide, polycarbonate, glass-filled nylon, polyether ester ketone (PEEK) and polyetherimide [7]. In SLS and multijet techniques, polyamides and thermoplastic polyurethane are most commonly used [15].
Polymer 3D Bioprinting for Bionics and Tissue Engineering Applications
Published in Atul Babbar, Ranvijay Kumar, Vikas Dhawan, Nishant Ranjan, Ankit Sharma, Additive Manufacturing of Polymers for Tissue Engineering, 2023
Vidyapati Kumar, Atul Babbar, Ankit Sharma, Ranvijay Kumar, Ankit Tyagi
When heated, these materials soften and become moldable, and when cooled, they solidify to generate the desired shape. The procedure may be repeated because the long-chain polymers are held together by a weak Vander Waals force. Thermoplastic polymers include polyethylene, polystyrene, nylons, polycarbonate, and polyether imide, and thermoplastic products are manufactured employing conventional methods such as injection molding and material extrusion. However, leveraging thermoplastic polymer, 3D printing technologies such as fused deposition modelling (FDM) and selective laser sintering (SLS) can manufacture complex objects. Thermoplastic polymers often used in FDM include acrylonitrile butadiene styrene, polylactide, polyamide, polycarbonate, glass-filled nylon, polyether ester ketone (PEEK), and polyetherimide (Alghamdi et al., 2021). Polyamides and thermoplastic polyurethanes are often used in SLS and multi-jet techniques (Schmid & Wegener, 2016).
Dielectric spectroscopy of PETG/TiO2 composite intended for 3D printing
Published in Virtual and Physical Prototyping, 2023
Petr Veselý, Denis Froš, Tomáš Hudec, Josef Sedláček, Pavel Ctibor, Karel Dušek
FDM provides fabrication of objects using polymers that can be melted, deposited with appropriate viscosity to adhere, and then solidified again while keeping the original properties. Favoured thermoplastics applicable for FDM are polylactic acid (PLA), polyethylene terephthalate glycol-modified (PETG), acrylonitrile butadiene styrene (ABS), polycarbonate (PC), and polypropylene (PP) (Ngo et al. 2018; Shahrubudin, Lee, and Ramlan 2019). Acrylonitrile styrene acrylate (ASA) is another promising material capable of replacing ABS since it has better thermal properties and is more resistant to UV irradiation (Afshar and Wood 2020; Kalaš et al. 2021). Printed products are usually compared to those obtained by injection moulding. Certain drawbacks of FDM have been pointed out. The missing pressure during printing brings about weakened mechanical properties (Dawoud, Taha, and Ebeid 2016). Moreover, the mechanical endurance varies according to the printing direction. The anisotropy behaviour must be evaluated in terms of product deployment. FDM printed parts are also prone to moisture absorption because of the high porosity rate. These two concerns may be successfully eliminated by utilising some of the post-processing techniques (Tamburrino et al. 2021).
A holistic approach of reconfigurable mould based fused deposition modelling for producing overhanging parts
Published in Australian Journal of Mechanical Engineering, 2023
Vikrant Charak, Amit Kumar Sinha, Ankush Anand
FDM has a major drawback in terms of the requirement of the support structure, high build time, low surface finish, low mechanical strength, and various restrictions in the use of different materials. Although, FDM is used for producing intricated parts. However, manufacturing of overhanging parts suffers from basic inabilities like special support structure, high build time, low surface finish, low mechanical strength, etc. In this regard, novel research is carried out by Cadiou, Demoly, and Gomes (2021). Cadiou, Demoly, and Gomes (2021) developed a hybrid additive manufacturing method based on a fused filament fabrication platform and direct ink writing techniques. But, still, it is hard to develop a quality product for complex overhanging parts using a 3D printer. Therefore, a holistic approach in FDM for producing overhanging parts is required. In the present research work, a reconfigurable mould-based integrated FDM approach has been proposed for producing overhanging parts. Another salient feature of the proposed research is an overall holistic approach has been discussed for handling various drawbacks of FDM. Basic remedial actions are also suggested in the present research work.
Predictive modelling of surface roughness in fused deposition modelling using data fusion
Published in International Journal of Production Research, 2019
Dazhong Wu, Yupeng Wei, Janis Terpenny
Additive manufacturing, also referred to as 3D printing or freeform fabrication, is a manufacturing process where three-dimensional objects are built by joining materials layer by layer as opposed to traditional subtractive manufacturing processes (Gibson, Rosen, and Stucker 2010; Gao et al. 2015; Bourell et al. 2017; Kusiak 2018). According to a report by PwC, additive manufacturing has advanced and grown into a technology with a market size that reached US $5.1 billion in 2015 (Ford and Despeisse 2016). Gartner Research estimates that nearly 5.7 million 3D printers will be built annually by 2019, compared to an estimated 500,000 printers in 2016 (Weller, Kleer, and Piller 2015). According to ASTM International, additive manufacturing processes fall into seven categories: (1) material extrusion, (2) powder bed fusion, (3) vat photopolymerisation, (4) material jetting, (5) binder jetting, (6) sheet lamination, and (7) directed energy deposition. According to a report by Sculpteo in 2017 (Sculpteo 2017), the most used 3D printing technologies include fused deposition modelling (FDM) (36%), selective laser sintering (33%), stereolithography (25%), multijet/polyjet (13%), direct metal laser sintering (8%). Plastic (88%) is still the most used 3D printing material, followed by resins (35%), metals (28%), multicolore/sandstone (15%), wax (11%), and ceramics (8%). FDM builds parts by extruding strings of the solid thermoplastic filament. The filament is fed from a filament spool through a heated extrusion nozzle. The filament is heated past its glass transition temperature and then deposited in a layer-by-layer manner. The most popular thermoplastic materials used in FDM include polylactic acid (PLA) and acrylonitrile butadiene styrene (ABS).