3D Printing and Polymers

16 min readSep 12, 2021

Disclaimer: All images are taken from Google or respective research paper.

INTRODUCTION

The term “3D printing” can refer to a variety of processes in which material is deposited, joined or solidified under computer control to create a three dimensional object object, with material being added together (such as plastics, liquids or powder grains being fused together), typically layer by layer. 3D printing, or additive manufacturing, is the construction of a three-dimensional object from a CAD model or a digital 3D MODEL.

Three-dimensional (3D) printing is an additive manufacturing process in which a physical object is created from a digital design by printing thin layers of material and then fusing them together. Some industries, such as hearing aids manufacturers, airline manufacturers, and car manufacturers, use 3D printing to create prototypes and mass produce their products using custom scans.

ADDITIVE MANUFACTURING (AM)

Additive manufacturing applications appear to be almost limitless. Early use of 3D printing in the form of rapid prototyping focused on preproduction models. However, additive manufacturing is now being used to fabricate: High-tech industrial( aerospace, medical, automotive) and Consumer ( home, fashion, and entertainment) product.

Overall, the demand in the global 3D Printing market. is gaining traction from a number of factors such as:

• Strikingly higher resolution

• Reduction in manufacturing cost owing to recent technological advancements

• Ease in the development of customized products

Growing possibilities of using multiple materials for printing.

ADVANTAGES:-

Elimination of design constraints

Allow parts to be produced with complex geometry: honeycomb structures, cooling channels, etc, and no additional costs related to complexity. And no expensive tooling requirements Well suited to the manufacture of high value replacement and repair parts and wide range of materials.

DISADVANTAGES:-

Surface roughness and low density, porosity.

Lack of data regarding end-use properties to be expected of parts. Limited to relatively small parts low volume manufacturing.

TECHNIQUES:-

1. Material extrusion :- It is an additive manufacturing process in which material is selectively dispensed through a nozzle. Fused deposition modeling (FDM), fused filament fabrication (FFF), 3D dispensing, and 3D bioplotting fall into this category.

2. Material jetting :- It is an additive manufacturing process in which droplets of build material (such as photopolymer or thermoplastic materials) are selectively deposited. Systems based on inkjet printing fall into this category.

3. Binder jetting :- It is an additive manufacturing process in which a liquid bonding agent is selectively deposited to fuse powder materials.

4. Sheet lamination :- It is an additive manufacturing process in which sheets of material are bonded together to form an object.

5. Vat photo polymerization:- It is an additive manufacturing process in which liquid photopolymer in a vat is selectively cured by light-activated polymerization. Many of the lithography-based AM approaches (e.g., multi photon polymerization (2PP), digital light processing (DLP), and stereolithography (SLA)) can be grouped into this category.

6. Powder bed fusion :- IT is an additive manufacturing process in which thermal energy (provided by a laser or an electron beam) selectively fuses regions of a powder bed. Selective laser sintering (from 3D Systems) and laser sintering (from EOS), both of which are abbreviated in this Review as SLS, and electron beam machining (EBM) fall into this category.

7. VAT polymerization :- VAT polymerization is an additive manufacturing technology which uses photopolymer materials cured by the ultraviolet (UV) laser beam. Photopolymer receives energy activating electrons in the initiators reacting with the functionals groups starting polymerization process.

COMPUTER AIDED DESIGN (CAD)

It is the use of computers (or workstations) to aid in the creation, modification, analysis, or optimization of a design. CAD software is used to increase the productivity of the designer, improve the quality of design, improve communications through documentation, and to create a database for manufacturing.

WORKING

There are a variety of 3D printing materials, including thermoplastics, metals (including

powders), resins and ceramics A typical 3D printer is very much like an inkjet printer operated from a computer. It builds up a 3D model one layer at a time, from the bottom upward, by repeatedly printing over the same area in a method known as fused depositional modeling (FDM). Working entirely automatically, the printer creates a model over a period of hours by turning a 3D CAD drawing into lots of two-dimensional, cross-sectional layers — effectively separate 2D prints that sit one on top of another, but without the paper in between. Instead of using ink, which would never build up to much volume, the printer deposits layers of molten plastic or powder and fuses them together (and to the existing structure) with adhesive or ultraviolet light.

STL FILE

An STL file is a simple, portable format used by computer aided design (CAD) systems to define the solid geometry for 3D printable parts. An STL file provides the input information for 3D printing by modelling the surfaces of the object as triangles that share edges and vertices with other neighbouring triangles for the build platform. The resolution of the STL file impacts the quality of the 3D printed parts — if the file resolution is too high the triangle may overlap, if it is too low the model will have gaps, making it unprintable. Many 3D printers require an STL file to print from.

POLYMERS

1. POLYCARBONATE(PC)

PC is highly valued by the additive manufacturing industry for its strength and transparency. It has a much lower density than glass, making it particularly interesting for designing optical parts, protective screens or decorative objects. The polycarbonate filament can withstand temperatures ranging from -150°C to 140°C, thus expanding the number of possible applications :-

• PC requires high temperatures to extrude properly and prone to warping and shrinkage.

• PC absorbs moisture and heat resistant up to 135 °C.

• highly durable, impact and shatter resistant and moderately flexible.

• transparent and electrically non-conductive

2. ACRYONITRILE BUTADINE STYRENE(ABS)

Valued for its strength and safety, ABS is a popular option for home-based 3D printers. Alternately referred to as “LEGO plastic,” .ABS is available in various colours that make the material suitable for products like stickers and toys.

Material product:-

• resistance to impact and high temperature (between -20°C and 80°C).

• It is opaque, offers smooth and shiny surfaces.

• It can be welded by chemical processes using acetone

• It has a melting temperature of around 200°C.

3. NYLON PA12

Nylon PA12 is a 3D printing material made out polyamide powder and printed using Selective Laser Sintering (SLS), a powder bed fusion technology, to create your 3D models. This material is both solid and flexible, it depends on the wall thickness of your part. This plastic is particularly suited for rapid prototyping, as the printing process is cheaper and faster. Moreover, a lot of surface finishes and wide-range of colours can be added to your Nylon PA12.

4. ACRYLIC STYRENE ACRYLONITRILE (ASA)

ASA, also known as Acrylic Styrene Acrylonitrile, is a 3D printable plastic with properties similar to ABS. It was originally developed as an alternative to ABS that would be more UV resistant by changing the type of rubber that’s used in the formulation. ASA is known for high impact resistance, higher temperature resistance, and increased printing difficulty. It’s commonly used in outdoor applications instead of ABS due to its superior resistance to UV and harsh weather conditions.

5. POLYCAPROLACTONE(PCL)

PCL, which stands for “Polycaprolactone”, is one of many polymers that have been attempted for use in 3D printing applications. The plastic offers good 3D printing qualities, such as layer adherence, which should reduce de-lamination from stress along layer boundaries. It also provides excellent impact strength and durability. But the major feature of PCL is its melt temperature, which is only a mere 60C, far below commonly used 3D printer materials such as PLA and ABS, which have melt temperatures in the 200C+ range.

6. CARBON FILLED FIBRE

Carbon fiber filaments use tiny fibers that are infused into a base material to improve the properties of that material. Several popular filaments can be bought with carbon fiber fill including PLA, PETG, Nylon, ABS, and Polycarbonate. These fibers are extremely strong and cause the filament to increase in strength and stiffness. This also means that the 3D printed parts will be much lighter and more dimensionally stable, as the fibers will help prevent shrinking of the part as it cools.

7. HIGH IMPACT POLYSTYRENE (HIPS)

HIPS or High Impact Polystyrene are plastic filaments that are used for support structures in FDM printers. It comparable to ABS when it comes to ease of use. The only difference is its ability to dissolve. HIPS is completely soluble to a liquid hydrocarbon called limonene.

Characteristics :-

• It has good machinability. It can also be used to make complex structures.

• It is very smooth and lightweight.

• It is water resistant and impact resistant and inexpensive.

8. POLYETHER BLOCK AMIDE (PEBA)

PEBA (or Polyether Block Amide) is another plastic material 3D printed using SLS printing process. This material is particularly interesting has it is a rubber-like material, resistant to stress and fatigue. This material will enable you to create fully-functional models and flexible plastic parts, you could use this material for a lot of different applications from insoles, to medical models.

9. RESINS

Compared to other 3D-applicable materials, resin offers limited flexibility and strength. Made of liquid polymer, resin reaches its end state with exposure to UV light. Resin is generally found in black, white and transparent varieties, but certain printed items have also been produced in orange, red, blue and green.

Material properties :-

• Resin is a thermoset that can work with temperatures above 200 °C.

• Tensile strength 65 MPa.

CATEGORIES :-

• PAINTABLE RESIN : Sometimes used in smooth-surface 3D prints, resins in this class are noted for their aesthetic appeal. Figurines with rendered facial details, such as fairies, are often made of paintable resin.

• TRANSPARENT RESIN : This is the strongest class of resin and therefore the most suitable for a range of 3D-printed products. Often used for models that must be smother to the touch and transparent in appearance.

• ELASTOMERIC RESIN : Elastomeric Polyurethane, also known as EPU, is a high- performance polyurethane elastomer. This resin material offers excellent elastic behavior under cyclic tensile and compressive loads. elastomeric Polyurethane is 3D printed through DLS

process, (for Digital Light Synthesis) or CLIP process (for Continuous Liquid Interface Production).

• FLEXIBLE POLYURETHANE : Flexible Polyurethane, also called FPU, is a semi-rigid material with good resistance to impact, abrasion and fatigue. This versatile resin material was designed for applications that require the toughness to withstand repetitive stresses such as hinging mechanisms and friction fits. It is a good flexible material, but not as flexible as PEBA, the rubber-like plastic we told you about before.

• URETHANE METHACRYLATE: Here is another resin using the CLIP process: the Urethane Methacrylate resin, or UMA 90. Parts printed with the CLIP technology are much more like injection moulding objects. The absence of post-production treatment shortens the production time and lowers the costs of production, which makes UMA perfect for fast and efficient prototyping, manufacturing tooling and fixtures.

PROPERTIES OF POLYMERIC MATERIAL FOR ADDITIVE MANUFACTURING

The properties of new materials must be compatible with the deposition tool as well as the application. Some of the properties for new, sought-after polymeric materials include:

MECHANICAL STABILITY :- The material should maintain its form during processing including the support of subsequent layers. High mechanical stability of the final part allows it to be handled quickly and provides property imitation of conventionally processed materials (e.g. by injection moulding).

CHEMICAL STABILITY:- The material has to have a consistent chemical structure and it must be inert when in contact with other materials during and after processing. This will allow possible combination with other materials without undesirable reactions.

THERMAL STABILITY :- The material should have properties (melt flow, particle size, adhesion, etc.) that are required for the additive manufacturing processes chosen.

BIOCOMPATIBILITY:- Biocompatibility will become important in AM parts that are manufactured for biological applications such as bodily implants and orthodontics. It will also become significant in parts that must be recycled or deposited in a waste facility.

APPLICATION OF POLYMER IN 3D PRINTING

AEROSPACE AND DEFENCE

Concept modeling and prototyping. Manufacturing low-volume complex parts (electronics, engine parts, etc.). Manufacturing replacement parts anywhere. Manufacturing structures using lightweight, high strength materials.

Example:- GLASS FILLED NYLON,NYLON 12

AUTOMOBILE

Testing part design to verify correctness and completeness. Parts for race vehicles, luxury sports

cars, antique cars, etc. Replacement of parts that are defective or cannot be purchase. Manufacturing structures using lightweight, high strength materials

Example:- polyamide 6, NYLON PA11, polypropylene.

ELECTRONIC

Embedding Radio Frequency Identification (RFID) devices embedded inside solid materials. Short lead time electronic products. Polymer based, three-dimensional micro-electromechanical systems. Microwave circuits fabricated on paper substrates.

TOOLS AND MOULD MAKING

Universal tool holders with standardised pocket sizes. Die casting forms. Injection molding tooling. Tooling for prototyping of short lead time surgical devices.

MEDICAL

Design and modeling methods for customized implants and medical devices. Processes for fabrication of “smart scaffolds” and for construction of 3D biological and tissue models.

Example;- PEEK (Polyetheretherketone), PEKK(Polyetherketoneketone), PPSU(Polyphenylsulfone)

ARTIFICIAL INTELLIGENCE AND 3D PRINTING

Additive manufacturing of three-dimensional objects are now more and more realised through 3D printing, known as an evolutional paradigm in the manufacturing industry. Artificial intelligence is currently finding wide applications to 3D printing for an intelligent, efficient, high quality, mass customised and service-oriented production process. The prefabrication of slicing is accelerated through parallel slicing algorithms and the path planning is optimised intelligently. In the aspect of service and security, intelligent demand matching and resource allocation algorithms enable a Cloud service platform and evaluation model to provide clients with an on-demand service and access to a collection of shared resources. Based on the reviews on various applications, printability with multi-indicators, reduction of complexity threshold, acceleration of prefabrication, real-time control, enhancement of security and defect detection for customised designs are seen of good opportunities for further research, especially in the era of Industry.

Bridges are started to be constructed with robotic 3D printers in Netherlands. There are a lot of examples how 3D printing technologies have been already implemented in ordinary life.

Combination of AI and AM should improve manufacturing process and develop new technologies.

DESIGN AND NEW MATERIAL

This new development in engineering is enabling scientists and engineers to design a new class of materials that are stronger, lighter, more flexible, and less expensive to manufacture and thereby addresses the key challenges the industry has to tackle. Machine learning, and predictive modelling, a powerful subset of AI, are being used to accelerate the discovery of these new materials.

4D Printing

Using 3D printing and multi-material structures in additive manufacturing has allowed for the design and creation of what is called 4D printing. 4D printing is an additive manufacturing process in which the printed object changes shape with time, temperature, or some other type of stimulation. 4D printing allows for the creation of dynamic structures with adjustable shapes, properties or functionality. The smart/stimulus responsive materials that are created using 4D printing can be activated to create calculated responses such as self-assembly, self-repair, multi-functionality, reconfiguration and shape shifting. This allows for customized printing of shape changing and shape-memory materials.

The future of 3D printing

Many people believe 3D printing will herald not merely a tidal wave of brash, plastic gimmicks but a revolution in manufacturing industry and the world economy that it drives. Although 3D printing will certainly make it possible for us to make our own things, there’s a limit to what you can achieve by yourself with a cheap printer and a tube of plastic. The real economic benefits are likely to arrive when 3D printing is universally adopted by big companies as a central pillar of manufacturing industry. First, that will enable manufacturers to offer much more customization of existing products, so the affordability of off-the-shelf mass-production will be combined with the attractiveness of one-off, bespoke artisan craft. Second, 3D printing is essentially a robotic technology, so it will lower the cost of manufacturing to the point where it will, once again, be cost-effective to manufacture items in North America and Europe that are currently being cheaply assembled (by poorly paid humans) in such places as China and India. Finally, 3D printing will increase productivity (since fewer people will be needed to make the same things), lowering production costs overall, which should lead to lower prices and greater demand — and that’s always a good thing, for consumers, for manufacturers, and the economy.

Artificial Intelligence and 3D Printing

Additive manufacturing of three-dimensional objects are now more and more realised through 3D printing, known as an evolutional paradigm in the manufacturing industry. Artificial intelligence is currently finding wide applications to 3D printing for an intelligent, efficient, high quality, mass customised and service-oriented production process. The prefabrication of slicing is accelerated through parallel slicing algorithms and the path planning is optimised intelligently. In the aspect of service and security, intelligent demand matching and resource allocation algorithms enable a Cloud service platform and evaluation model to provide clients with an on-demand service and access to a collection of shared resources. We also discuss to detect product defects in the presence of cyber-attacks. Based on the reviews on various applications, printability with multi-indicators, reduction of complexity threshold, acceleration of prefabrication, real-time control, enhancement of security and defect detection for customised designs are seen of good opportunities for further research, especially in the era of Industry 4.0.

Artificial Intelligence and 3D printing are technologies that are still developing and getting more important every day.In order to reach this magnificent future, countries should unite their local additive manufacturing markets and cooperate on developing and distributing 3D printing technologies around the world. United Kingdom, United States and most of the leading European countries are entering the digital manufacturing era. For example, “Airbus” company uses most of the parts for airplanes designed and manufactured with AM (Attaran, 2017). Almost all engineering materials are working in AM field too. Bridges are started to be constructed with robotic 3D printers in Netherlands. Specific athlete shoes are partly made with AM technologies in US. There are a lot of examples how 3D printing technologies have been already implemented in ordinary life.Combination of AI and AM should improve manufacturing process and develop new technologies.

Defect Detection

Using AI in 3D printing could further optimize the printing process and help avoiding errors: The joint force of these technology could develop tools that are able to find defects that could make the model non-printable in a 3D model. A real-time control by the AI could considerably reduce time and material waste. Also, AI could be used after the printing process to detect problems directly, and to improve the quality control of the 3D printed models.

AI Build, a company based in London, already developed an automated AI-based 3D printing technology, with a smart extruder, allowing to detect problems: Their “AiMaker” is a high precision robotic end-effector that attaches to industrial robotic arms and is able to 3D print large objects at high speed with great accuracy.

Precision and Reproducibility

This technology quickly corrects computer-aided design models and produces parts with improved geometric accuracy. It ensures that the printed parts

conform more closely to the design and remain within necessary tolerances. This method also leads to improved consistency, assuring that the part will perform the same way even if it’s printed on a different machine. It’s also able to create complex designs that would not be possible with traditional manufacturing processes.

Designs and New Materials

Prefabrication

With the increasing design complexity, the optimisation of computational prefabrication, also known as process planning, has become a hot issue of 3DP [4]. At present, lots of researchers have proposed their methods to accelerate prefabrication

CONCLUSION

Additive manufacturing, has shown how AM is as much an interesting way of thinking about manufacturing as it is a new way of constructing components. As computing systems have become more powerful, the availability of software to ‘slice ’CAD models for layer-by-layer construction has paved the way for AM to thrive.

A material processed by AM will often have very different properties compared with the same material processed using a traditional method. Furthermore, residual stress is an issue for all processes that experience large variations in temperature; additively manufactured components are no exception. Almost all AM techniques utilise thermoplastic or thermoset polymers as build materials. The rise to prominence of AM has been inherently tied to improvements in the understanding of the processing of these polymers. Particularly, eliminating the need for post processing steps is essential for improving AM competitiveness.

Focus is increasingly shifting toward the functionality of the printed object and thus on mechanical and other material properties. Regardless of whether powder- or extrusion-based AM is used, it is imperative to fuse together polymer layers, preventing formation of pores and structural inhomogeneity, both of which are highly detrimental to mechanical strength, durability, and surface finish. Polymer layer fusion can be achieved by tailoring photopolymer systems or polymer particles for laser sintering, or by developing special binders and inks as fusion agents for binder- jetting. During the pioneering days of the 1990s when focus was on rapid prototyping, precise geometry and surface appearance were prime concerns.

References:

A.M.T. Syed, P.K. Elias, B. Amit, B. Susmita, O. Lisa, C. Charitidis “Additive manufacturing: scientific and technological challenges, market uptake and opportunities” Materials today, 1 (2017), pp. 1–16

V. Rajan, B. Sniderman, P. Baum “3D opportunity for life: Additive manufacturing takes humanitarian action” Delight Insight, 1 (19) (2016), pp. 1–8

W. Yuanbin, Blache, X. Xun “Selection of additive manufacturing processes” Rapid Prototyping Journal, 23 (2) (2017), pp. 434–447

L.Y. Yee, S.E.T. Yong, K.J.T. Heang, K.P. Zheng, Y.L. Xue, Y.Y. Wai, C.H.T. Siang, L. Augustinus “3D Printed Bio-models for Medical Applications” Rapid Prototyping Journal, 23 (2) (2017), pp. 227–235