3D Printing and its Future
This section is the explanation on background history and also research journal of other people in the subtopic of this research. The title covers for this literature review are three-dimension printer (3D printer), 3D Printing Process, Advantages and limitations of 3D Printing, and explanation of Acrylonitrile Butadiene Styrene (ABS) material properties.
Three-dimension printer (3D printer)
Additive manufacturing (AM), also known as 3D Printing is involves the utilization of layer-by-layer manufacturing in order to build a piece of the component part by addition of material (Petrovic, Jordá, DelgadoBlasco, Jose, & Portolés, 2009). Additive manufacturing (AM) additionally allows and modified a mass of items that can be independently customized (Attaran, 2017). Additive manufacturing process procedure the last condition of result of the part by including materials, which is contrasted with regular procedures that deliver items by disposing of materials from an expansive raw material.
This technology is truly an effective way to produce a product with endless design difficulties and has high probability to amplify global supply chain capabilities. Because of that, the usage of the technology is increased year by year especially in making a small component. The phrasing additive manufacturing designated to the technology of storing progressive thin layers of material upon each other by fabricate a last three-dimensional item.
Each layer is around 0.001 to 0.1 inches in thickness (Attaran, 2017) . In addition, additive manufacturing can generate a complex geometry of a product which means that can be customize anything by tweaking a part of the prototype, so it can satisfy the needs. According (Dakshnamoorthy, 2016), one of the capabilities enabled by additive manufacturing is hierarchical complexity, i.e., the capacity to manufacture features at numerous size scales: micro, meso and macro. By utilizing a 3D printer, they can print the parts on request, along these lines sparing resources and creating less waste.
Unfortunately, there some restriction which limit additive manufacturing from generating a good product. Since the industry only started to raise markedly after 2009, the industry is still very new, and technological developments in 3D printing, as well as the finding of new applications of the technology, are still in development. It might be various years required before additive manufacturing really creates mass produce and different mold in a broad way. The major circumstances to implementation are stated below and range from the size of objects manufactured, to government, liability, and intellectual property issues: (Attaran, 2017)
Constrained decisions for materials, hues, and surfaces
Greater expense for enormous creation runs.
Restricted strength and resistance to heat & motions & color stability
Low design of product dimensions
Lower precision relative to other technologies
3D printing process
The 3D printing technology consists of three main phases – the modelling, the printing and the finishing of the product:
In the modelling phase, in order to obtain the printing model, the machine uses virtual blueprints of the object and processes them in a series of thin cross-sections that are being used successively. The virtual model is identical to the physical one.
In the printing phase, the 3D printer reads the design (consisting of cross-sections) and deposits the layers of material, in order to build the product. Each layer, based on a virtual cross section, fuses with the previous ones and, finally, after printing all these layers, the desired object has been obtained. Through this technique, one can create different objects of various shapes, built from a variety of materials (thermoplastic, metal, powder, ceramic, paper, photopolymer, liquid).
The final phase consists in the finishing of the product. In many cases, in order to obtain an increased precision, it is more advantageous to print the object at a higher size than the final desired one, using a standard resolution and to remove then the supplementary material using a subtractive process at a higher resolution.
Depending on the employed manufacturing technique, the 3D printing could offer additional improvements. Thus, in the printing process, one can use multiple materials in manufacturing different parts of the same object or one can use multiple colours. If necessary, when printing the objects, one can use certain supports that are being removed or dissolved when finishing the product.
Taking into account the importance of the 3D printing technology, we have decided to analyses further the main available additive processes, the advantages and limitations of this technology, to compare the most significant existing 3D printing solutions. We have also decided to study the usefulness, the implications and the future evolution that the 3D printing technology brings into the modern society, economy and everyday life.
Categories of 3D printing
Material Extrusion is a 3D printing process where a filament of solid thermoplastic material is pushed through a heated nozzle, melting it in the process. The printer deposits the material on a build platform along a predetermined path, where the filament cools and solidifies to form a solid object.
Vat Polymerization is a 3D printing process where a photo-polymer resin in a vat is selectively cured by a light source. The two most common forms of Vat Polymerization are SLA (Stereolithography) and DLP (Digital Light Processing).
The fundamental difference between these types of 3D printing technology is the light source they use to cure the resin. SLA printers use a point laser, in contrast to the voxel approach used by a DLP printer.
Powder Bed Fusion is a 3D printing process where a thermal energy source will selectively induce fusion between powder particles inside a build area to create a solid object. A typical powder bed fusion machines apply thermal energy directly on the powder bed to fuse materials in the selective area, and after a materials cool down to form solid structures, another layer of powders were applied on top and repeat the process. (Annas Fatihah Binti Muhamad, 2017).
Material Jetting is a 3D printing process where droplets of material are selectively deposited and cured on a build plate. Using photopolymers or wax droplets that cure when exposed to light, objects are built up one layer at a time. Through deposition of the fused material in layers. It also uses a filament of thermoplastic polymers to manufacture the model.
Advantages and disadvantage of 3D printing
In order to analyse the impact of 3D printing technology on the mechanical properties, in the following we study its main advantages and limitations.(Pirjan & Petrosanu, 2013)
Additive manufacturing offers the possibility of creating, in a short timeframe, complex 3D objects, with fine details, from different materials. Through 3D printing, the customer has the possibility to create complex objects and shapes that are impossible to be obtained through any other existing technology.
A very important advantage of creating objects using 3D printing technology instead of traditional manufacturing methods is the waste reduction. As the construction material is added layer after layer, the waste is almost zero and during the production, it is used solely the material needed for obtaining the final object.
In the traditional manufacturing processes, based on subtractive techniques, the final product is manufactured through cutting or drilling an initial object, thus leading to a substantial loss of material. One can easy print small movable parts of the final object. Some of the materials used in 3D printing have improved properties in terms of strength and provide a wide range of superior finishing details, compared to the materials used when manufacturing objects through traditional technologies.
As the additive manufacturing is a computer-controlled technique, it reduces the necessary amount of human interaction and requires a low level of expertise for the operator. Furthermore, the process ensures that the final product represents a perfect 3D version of the digital design, excluding the errors that could have appeared when using other existing technologies. As the AM reduces the waste in the manufacturing process, it could help solving tough problems of the humanity such as the consumption of the construction material resource, the energy consumption and the environmental protection.
Common with other technology, 3D printing has a series of disadvantages and limitations that currently obstruct a large-scale expansion of this technology. The main disadvantages and limitations of 3D printing are:
A major disadvantage of 3D printing is its high cost. At the actual price of the device and materials, the 3D printing is the best solution when one needs to print a small number of complex objects, but it becomes expensive to print a large number of simple objects, when compared to traditional manufacturing techniques. In addition, the 3D printing becomes unprofitable when printing large size objects. The cost of a 3D printed large object is significantly higher than if it had been traditionally manufactured.
Due to the material costs (especially regarding the molds), the additive manufacturing is not always the best technical choice, most of the molds’ materials being degradable over time and sensible at outdoor exposure.
Sometimes, the 3D printed objects’ building quality is lower than if it had been traditionally manufactured. Although the additive manufacturing can print objects having intricate designs, the final product can sometimes have flaws that might affect not only the object’s design, but also its functionality and resistance.
Acrylonitrile Butadiene Styrene
Acrylonitrile Butadiene Styrene (ABS) is a common 3D-printing filament material. Different grades of the plastic exist, as with all plastics, due to having different degrees of polymerization, and crystallinity, variation in chain length distribution, and added plasticizers and dyes. ABS is particularly variable due to the fact that the three monomers used in its production can be added in different ratios and at different stages, resulting in both blends and copolymers that are labeled as ABS. The form of ABS used for printing filament is very similar to that used in injection-molded parts such as Lego bricks. (Wa & Wa, 2017)
ABS produce toxic gases while melting, producing a notable scent and causing headaches quickly. It is always recommended to make sure any ABS FDM is done in a well-ventilated space. ABS is favored for its rheological properties which make relatively smooth surfaces in FDM. ABS plastic is not resistance to many solvents, but this can be used as an advantage when smoothing the surface of printed parts using an acetone wash or vapor.
Comparison of ABS and PLA Properties
Table 2 : Comparison of ABS and PLA
Acrylonitrile butadiene styrene PLA
Polylactic acid or polylactide
Molecular Formula (C8H8·C4H6·C3H3N)n (C3H4O2)n
Environmentally Friendly? No Yes
Degradable? No Yes
Melting Point 205 C 175 C
Rockwell Hardness R105 TO R110 R70 TO R90
Surface Quality FINE GOOD
Cool Time MEDIUM LONG
Moisture Absorption Approx. 3%-5% Minor
Density 〖1.04 g/cm〗^3 1.23 to 1.25 g/cm
Elongation at Break 20% 3.8%
Glass Transition 221ºF (105ºC) 140-149ºF (60- 65ºC
Tensile Strength 6,500 psi (44.81 MPa) 8,383.18 psi (57.8 MPa)
Flexural Strength 11,000 psi (75.84 MPa) 8,020.58 psi (55.3 MPa)
Tensile Modulus 320,000 psi (2.21 GPa) 478,624.53 psi (3.3 GPa)
Flexural Modulus 330,000 psi (2.28 GPa) 333,586.79 psi (2.3 GPa)
The table shows strength-to-weight ratios of the various infill geometries were compared. It was found through tensile testing that the specific ultimate tensile strength (MPa/g) decreases as the infill percentage decreases and that hexagonal pattern infill geometry was stronger and stiffer than rectilinear infill. However, in finite element analysis, rectilinear infill showed less deformation than hexagonal infill when the same load was applied. (Farbman & McCoy, 2016)
Process Parameter in 3D Printing
Printing Speed is the speed at which the printing head moves while expelling the filament to make the physical portrayal of the 3D model. Depending on the model and the filament you use you may need to adjust the printing speed to be able to get good quality prints. Increasing the printing speed may help you get some prints a bit faster than usual, however too much increase of the speed may bring the result in bad quality and failing to print 3D models.
Wang et. al. 2011 mention that when material is extruded from the nozzle, it cools from glass transition temperature to chamber temperature causing inner stresses to be developed due to uneven deposition speed resulting in inter layer and intra layer deformation that appear in the form of cracking, delamination or even part fabrication failure. These phenomena combine to affect the part strength and size.
3D printing shells are the outlines or outer perimeters of each layer. Strength can be added by increasing shells thickness. This allows for a slightly more robust print without having to increase the amount of material used for infill. Most slicer programs allow shell thickness to be adjusted even allowing areas of high stress to be customized with a high shell density offering localized areas of high strength.
Mechanical properties of materials
Three most widely analysed mechanical properties of fused deposition modelling (FDM) parts are tensile strength, compressive strength and flexural strength. One of the most important considerations of the component to be applied in engineering applications is flexural strength (Kumar et al., 2018). (Divyathej, Varun, & Rajeev, 2016) explained on the definition of flexural strength, is the ability of a material to withstand bending forces applied perpendicular to its longitudinal.
The stress applied due to flexural load is the combination of compressive and tensile load. However, important mechanical tools for brittle materials is flexural strength that is significantly weaker in tension and compression (Fadhli & Bidin, 2019).
Regarding to (Divyathej et al., 2016), ways to obtain flexural properties is by calculating the maximum stress and strain that occurs at outside surface of the test bar. Then, testing on the flexural properties of thermoplastics is by using an international standard, ASTM D790 which typically used to find three-point loading system (Dey & Yodo, 2019) as shown in figure 9.
Therefore, the utilization of this technique for strength assessment of single segment brittle materials and layered structures such as glass façade on centre clay specimen and metal ceramic structured (Fadhli & Bidin, 2019). Unfortunately, flexural properties was not widely analysed for some parameters such as infill pattern, extrusion temperature and infill percentage (Dey & Yodo, 2019). Therefore, in this research, the mention parameters such as infill
Summary of literature review
Research on mechanical properties of ABS had been done before by other researchers but it is in different methodology. There is research on mechanical properties of ABS but not specifically mention the testing product that is produced by 3D printing and have research on blends material such as ABS/PVC. However, there is still lack of information on mechanical properties of ABS especially by using 3D printing in term of geometry shape.
As the result, this research can be related to the material properties that have been studied in section 2.5 which are ABS is a tough material that have high impact strength also high mechanical strength. Otherwise, there are a lot of 3D printing technology that could be considered and do commercial worldwide.
The researchers could more understand on how 3D printer work and the variable input that can manipulate the results by studied the 3D printer technology. In analysing the result, there are many types of testing to identify the mechanical properties of ABS. So, researchers need to know the type of testing to make sure the testing is suitable and obtain the valid data in this research.