thesis Archives - Perfect 3D Printing Filament

3D Printing in the Construction Industry: Still Evolving

In ‘Success Factors for 3D Printing Technology Adoption in Construction,” thesis student Pankhuri Pimpley at the University of Maryland, College Park, explores not only the history and benefits of 3D printing but also its effectiveness overall in a competitive, demanding market.

While 3D printing was created in the 1980s and introduced to the construction industry in the 90s, its purpose in that application was mainly for rapid prototyping. Such a process offers huge benefits to industrial users, but as with so many other industries and applications, it wasn’t long before ambitious users wanted to use digital fabrication to make real parts.

General 3D printing process (S. Lim et al., 2012)

As further advances in automation are still needed for the construction industry, 3D printing has become a very attractive option. The advantages abound too—from more savings on the bottom line to greater efficiency and less need for labor, to a continually expanding array of available materials. The author’s discussion as to why 3D printing is needed in construction is compelling:

“The construction industry has been slow in adopting new methods and innovations due to deep confidence in the efficiency of traditional processes, materials and codes. Since no change or innovation proposes growth of the sector, the construction industry has one of the lowest productivity increases compared to other industries. It is even more important to automate construction activities given the risks associated with it,” states the author.

“About 400,000 people are injured or killed every year in the USA during construction. These injuries and fatalities eventually translate to costs for society. Construction is also prone to corruption and political feuds. Hence the primary need for 3DP in construction is to reduce or eliminate human involvement in the design and development of the structure. It is also important that 3D printing be considered a standard construction practice by code bodies. Accepting the innovation can help set a common standard for global construction and solve the problem of labor skill variation from demographics and experience.”

3DP frame of concrete printing system (Sungwoo Lim et al.,2018)

Large-scale mobile printers are popular in the construction industry, and we have followed many of them such as the WASP 3D printer, which has been used for the beginnings of creating an entire community, along with tiny houses, and more. Pimpley points out numerous other examples too of companies with ambitious plans also, many of them eager to build small structures in record time—including Eindhoven University of Technology in the Netherlands, planning to print five single-story, two-bedroom residences.

Startups offering range of 3DP services

Pimpley also gave great attention to how socioeconomics might affect 3D printing, along with considering how to manage such factors in the future. One of the most important items that Pimpley points out, however, is that within the construction industry overall, the actual usefulness of 3D printing is ‘still limited.’ The author explains to us that this is due to certain issues related to society, the general market, and other business-related reasons.

“Nine success factors and forty-two corresponding measurement items have been identified and analyzed through literature review, case studies, surveys, interviews and correspondence with worldwide construction 3D printing experts and professionals. All factors are finally determined important to consider for the success of a construction 3DP project at its current phase. Relative significance of the factors and measurement items have been determined based on 82 questionnaire survey responses,” concluded the researcher.

“Altogether, the findings can help achieve an understanding of 3DP and increase the likelihood of successful adoption in various sectors within construction.”

Eindhoven’s proposed home design (“3D Printed Homes – 4 Most Fascinating Projects in 2019”, 2019, February 20).

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Additive Manufacturing Could Prove Promising in Development of Hydraulic Pumps

Saimaa University of Applied Sciences thesis student, Daniil Levchenko, explores the capabilities of complex 3D printing in ‘Design of a Hydraulic Pump for Construction with Additive Manufacturing Tools.’ While was and is well aware of some of the more exaggerated claims often made regarding the magic of 3D printing, Levchenko dedicated his thesis to examining the potential for fabricating a hydraulics system.

Levchenko’s focus is on prosumers, a group of users operating at the more advanced level in AM processes. The initial step was to outline what would be required for the hydraulics unit, and then begin examining the options for materials. After that, the researchers would design the pump, create a 3D model, 3D print the parts, and hopefully, test it in a lab.

“The idea of this study takes its origins in an article dedicated to a project of a group of engineering students from the University of Rhode Island,” states the author. “They designed, constructed, and tested a stabilization platform that would allow them to negate turbulent sea conditions and to use a 3D printer on-board. As one of the students specified, the project was directed to aid work of research ships that were located far from shores and might be needed for timely replacement of any piece of equipment.”

Stratasys Object30 Prime (on the left) and BCN3D Sigma (on the right) (BCN3D Technologies 2019 & Stratasys Ltd. 2016)

The three-month study was made up of two different parts: theoretical, and then a discussion/conclusion. Testing was performed on a Stratasys Objet30 Prime and a BCN3D Sigma 3D printer, with thermoplastic polymers chosen as the material, and tested regarding how it would mix with oil.

Materials that are available for the 3D printers

There were many obstacles encountered during the study, and the hydraulic pump was not completed. While the CAD model of the external gear pump was designed, the project was brought to a halt indefinitely due to complexities with the motor and then lack of a successful PLC-based controller circuit. There were time constraints on the brief three-month project too, with the study finally ending when neither parts for the pump-motor assembly or construction of the piece were coming to fruition.

Proposed gear (driving)

And although there was not an actual product to show for the research, Levchenko still sees the system as promising for developing areas where devices can be created on-site and on-demand; in fact, such pumps could offer critical services in rural or isolated geographies, especially with an accessible, mobile 3D printer that could fabricate affordable parts for wells and other machinery like hydraulic levers.

“The results of the theoretical study could have been implemented in a real-life model build with printers provided by the university. To the greatest regrets of the author, the conditions of the available machines required maintenance and they could not be used for concurrent construction. It should be possible to recreate the designed pump and test in laboratory conditions to acquire actual empirical data about its performance and reliability and to the overall applicability. It would also prove the viability of the concept,” concluded Levchenko.

“Another field to enlarge and improve this study could be the widening of the spectrum of the assessed materials and manufacturing techniques. An assumption of the author is that consideration and usage of selective laser sintering technique may greatly aid design freedom and the final properties of the pump. The technique is capable of creating geometries with good tolerances and surface tolerances.”

3D printing has been used in the design and fabrication of many different parts and systems to aid in helping developing countries and individuals in isolated areas, from the creating of manifolds to other hydraulic development and customized robotics. What do you think of this news? Let us know your thoughts! Join the discussion of this and other 3D printing topics at 3DPrintBoard.com.

A scheme of PolyJet printing process (The Technology House/Sea Air Space 2019)

[Source / Image: ‘Design of a Hydraulic Pump for Construction with Additive Manufacturing Tools’]

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University of Montana: Analyzing Accuracy of 3D Printed Femurs for Forensic Anthropology and Bioarchaelogy

Thesis student Myriah Adonia Jo Allen (University of Montana) discusses not only the implications of 3D scanning and 3D printing overall, but more specifically, how important the technology of 3D printing an item like a proximal right femur can be for anthropologists and bioarcheologists—and whether they can really be fabricated identically. The researcher’s findings are outlined in the recently published ‘3D Printing of the Proximal Right Femur: Its Implications in the Field of Forensic Anthropology and Bioarchaelogy.’

Preservation of relics and skeletal collections is a process that is continually being refined with new techniques and technologies. The author expresses grave concern for the safety of skeletal remains, especially after the catastrophes at both the Brazil National Museum and the Notre Dame cathedral—with fires causing great loss.

“Over the next few decades, many skeletal remains from across the globe will be removed from various collections and will then be given back to the claimants or put up where one cannot touch them. This results in fewer supplies that can be utilized for research purposes; therefore, it is necessary to retain information from the remains in as many ways as possible before they wither get returned or worse destroyed.”

The NextEngine Scanner being calibrated utilizing the palm tree

In this thesis study, Allen examined 18 different proximal right femoral ends obtained from the Forensic Anthropology Center at Texas State University. Referring to past research in replication of skeletal remains, the author points out that a variety of different materials have been used over the years with good accuracy; in fact, some have been good enough for use in the courtroom even, giving juries the chance to inspect copies of evidence—and providing forensics analysts and labs with a new technological resource on which to rely.

3D technology has added an interesting boost to biological archaeology also, in a range of different exhibits, museums, and learning institutions. One of the greatest benefits today is that museumgoers and other enthusiasts can touch 3D printed replicas without threatening the integrity of items that could be ancient and extremely fragile. Archaeologists and students can also enjoy handling delicate works without endangering them.

The femurs involved in the study were composed of a ‘mixed data set,’ with little deterioration. Allen chose to study this bone regarding 3D printing because so much data can be taken in from this small area. Using calipers and measuring tape, Allen took 11 sets of measurements for each femur in the study, as follows:

Maximum head diameter
Anterior-posterior (sagittal) subtrochanteric diameter (M2)
Medial-lateral (transverse) subtrochanteric diameter (M3)
Circumference of the head
Neck circumference
Superior neck length
Anterior-posterior neck diameter
Superior-inferior neck diameter
Coronal oblique plane/ upper epiphyseal length
Measurement of the intertrochanteric crest length
Platymeric Index

Items were then scanned and converted for 3D printing on a MakerBot, using PLA. Once support materials were removed, Allen measured them, comparing to the originals and analyzing any differences or errors, noting ‘an exciting find’ as upon comparing Table 2 and Table 3, there were only tiny differences—by a few millimeters.

“Even if some differences did occur, most likely due to intraobserver error this method does show statistical significance to be able to be utilized for accuracy. However, no constant error rate can be seen during the analysis. Therefore, this method has proved itself to be a useful method for the fields of forensic anthropology not only in terms of presenting to a jury, but also in terms of examination. As for bioarcheology, this method can also be useful in terms of preservation of archaeological remains that are currently on display in many countries around the world,” concluded the author.

This image constitutes of a group of 3D printed femurs. TX-16, on the far left and it shows that the print must be monitored every so often or else the printer might run out of filament and a change has to occur midprint. TX-17 in the middle left shows fall outs or little bumps on its surface because the extruder-point on the printer released too much filament at once, but it did not affect the overall measurements. TX-12 in the middle right shows what happens when the print gets too big for the printer. Lastly, TX-14.2 is another print taken of TX-14 to show what can happen when the printer arithmetically inputs structures.

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[Source / Images: ‘3D Printing of the Proximal Right Femur: Its Implications in the Field of Forensic Anthropology and Bioarchaelogy’]

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LSU: Thesis Student 3D Prints Strain Sensors for Electronics & Wearables

Louisiana State University thesis student, Austin Smith, hits the mark in exploring mechanisms for sensors in wearable electronics. In ‘Design and Fabrication of FDM 3D Printed Strain Sensors,’ the author explains that there is much more demand today for affordable sensors that can be created quickly due to the availability of flexible electronics requiring monitoring of movement.

Most strain sensor research has been focused on sensitivity, elasticity, and actual fabrication. Here, Smith sought to develop a way to integrate more than one sensor into a single device, using materials and techniques offering the capability for strength and performance. Samples of two different sizes: Type I at 2000 μm by 200 μm and Type II at 500 μm by 200 μm, allowed Smith a better chance to examine and evaluate the prototypes.

Representative Diagram of Embedded 3D printing based on Muth et al. procedure

Once created, each sensor consisted of:

Embedded channels (both long and short)
Conducting fluid
Substrate

“When an external force was applied, the channels deformed, and the cross-sectional area of the long channels reduced while the cross-sectional area of the short channels increased. As a result, the deformation of the long channels caused a reduction in the cross-sectional area of the conducting fluid. This change in area of the conducting fluid reduced the size of the path the current could flow through and thereby, increased its resistance,” stated Smith.

Cross-sectional view of the 3D printed strain sensor design.

Working principle of the channel effects when under applied strained.

Galinstan fluid was used for the research project because of conductivity and relative lack of toxicity, with Smith noting that the strain sensor pattern was suitable for single axis strain. An Ultimaker 3 3D printer was used to print the sensors, fabricated with Ninja Flex Thermoplastic Polyurethane. Overall, the research showed that a range of complex designs and sensor platforms can be created via FDM 3D printing.

Setting and parameters used to print the strain sensors using Ultimaker 3 3D printer.

“Nonetheless, issues related to strain offset, stress accumulation, and stress concentration were limiting factors. The way the FDM process formed the elastic substrates was such that the fibers were interwoven and at an angle with respect to the applied strain,” concluded the author. “This reduced the strain required to cause permanent deformation and strain accumulation in these fibers.

“These observations were highly relevant to the creation of 3D printed strain sensors as the patterning of the layers could alter the strain response of the strain sensor. Overall, FDM 3D printing has been shown to have potential as a method of simple and cost-effective fabrication of flexible strain sensors.”

As 3D printing and electronics continue to accompany one another in countless innovations today, sensors are a popular focus also for many different applications, from embedded components to biomedical sensors to fiber optics. Find out more about strain sensors in electronics like wearables here. What do you think of this 3D printing news? Let us know your thoughts! Join the discussion of this and other 3D printing topics at 3DPrintBoard.com.

[Source / Images: Design and Fabrication of FDM 3D Printed Strain Sensors]

Nanyang Technological University: Inkjet Printing of ZnO Micro-Sized Thin Films

In ‘Inkjet-printed ZnO thin film semiconductor for additive manufacturing of electronic devices,’ thesis student Van Thai Tran, from Nanyang Technological University, delves into the realm of fabricating products with conductive materials. As inkjet printing continues to gain popularity for researchers and manufacturers, it is the vehicle for creating a wide variety of innovations, to include tissue engineering and more. Here, however, Tran develops and examines ZnO thin film to promote electrical qualities in hopes of expanding 3D printing processes further overall.

The author understands the many benefits of 3D printing, as they have unfolded since the mid-80s. Today, the technology has progressed far beyond rapid prototyping, and a wide range of functional products are being made.

“It is expected that 3D printing will play a significant role in the fabrication of goods soon. As a result, the demand for printed functional devices has been raised to fulfill the need for printed consumable products, which are composed of multi-materials,” states Tran. “Hereby, the printed functional devices are not only basic electrical elements, such as resistors, capacitors, and transistors, but also advanced electric devices, such as sensor, solar cells and batteries.

“The construction of a product using 3D printing requires a combination of structural material and functional material. To accomplish the fully additive manufacturing process, printing of functional materials, such as conductor and semiconductor, is crucial.”

ZnO is helpful today in applications like:

Optoelectronics
Electronics
Sensors
Piezoelectric devices

Inkjet printing technologies: Continuous inkjet printing and Drop-on-demand Inkjet printing and electrohydrodynamic inkjet printing

Tran does raise concerns, however, regarding the use of ZnO in inkjet printing—such as the likelihood that it may cause band bending, resulting in defects in the 3D printed products. Band bending issues must be controlled and ‘engineered’ to create a device that is highly functional, lending central focus to this study, along with creating a successful way to improve on using the photolithography process, and investigating issues in annealing.

As an intrinsic n-type semiconductor, ZnO also possesses piezoelectric properties, capable of generating voltage under pressure—and causing it to be suitable for applications requiring sensors and actuators. As for thin film transistors, ZnO is an attractive option due to compatibilities with LCD applications and a variety of miniaturized electronics. As Tran mentions, ZnO is also especially suited to UV photodetector applications too.

In this project, Tran fabricated thin films via inket printing, but modifications were made with annealing—decreasing the band bending. The author also discovered that electrical properties were greatly improved due to heat treatment, with film conductivity impacted by band bending changes.

“The successful inkjet printing of micro-sized ZnO thin films and the integrated photodetector has demonstrated the feasibility and great potentials of fabricating sophisticated semiconductor devices using additive manufacturing technology,” concluded the author.

3D printing and electronics have been coupled together since the beginning, allowing for expansive innovations—and allowing many manufacturers to create items never possible. They are also able to enjoy much greater sustainability in production, whether in creating breakthrough techniques in manufacturing, liquid materials for electronic applications, or wearables. Find out more about semiconductors in AM manufacturing here.

Discuss this article and other 3D printing topics at 3DPrintBoard.com.

Additively fabricated ZnO nanostructures. (a) Selectively grown ZnO nanowire from inkjet-printed pattern (b) Electro-spinning ZnO nanowire

Printer structure and printing process to prepare the thin film. (a) Printer structure shows the main components and three-axes of the printer. (b) Optical photo of the printer. (c) Optical picture of the cartridge, including ink container and nozzles. (d) The schematic of the droplet watcher, which is the system to observe the generation of droplet before running the printing

[Source / Images: Inkjet-printed ZnO thin film semiconductor for additive manufacturing of electronic devices]

University of Mississippi: How to Trace 3D Printed Guns for Forensic Analysis

Parker Riley Ball is a thesis student at the University of Mississippi, exploring some complex areas regarding 3D printing, outlined in ‘Development of a Dart-Mass Spectral Database for 3D Printed Firearm Polymers, and Airborne Mercury at Three Lakes in North Mississippi.’

The research study, centered around the uses of chemometric analysis, offers an interesting focus on weapons forensics, as Ball expounds on ways to collect data on 3D printed guns and analyze the forensic information, along with creating another ‘sampling’ device (unrelated to 3D printing) for measuring high levels of mercury in Grenada, Enid, and Sardis Lakes, all tributaries in Mississippi.

Ball discusses the ‘threat of 3D printed firearms’ at length, delving into a worldwide conversation that is controversial to say the least. His point in the thesis is that there is a need to track weapons, and 3D printed guns are currently manufactured and possessed completely off the grid—along with safeguarding features such as the ability to evade metal detectors—prompting the possibility that there may be legal necessity in the future to track such weapons and their ‘manufacturers.’ Amidst exploration of DART-MS, the study of 3D printed guns, and forensic research, Ball mainly performed data analysis and interpretation, with the rest left up to fellow graduate student, Oscar Black.

DART-MS stands for direct analysis in real time – mass spectrometry and allows for the collection of ‘mass spectra under ambient conditions.’ Samples can be taken quickly, and simply. And while this is already a well-known technique for taking samples, using them for 3D printed gun forensics is a novel concept.

“With a DART ion source, a gas, He or N2, passes through a discharge chamber where an electric current is applied to generate a glow discharge, producing excited neutral chemical species called metastables,” explains Ball. “A perforated electrode removes ions from the gas stream as it travels through a second chamber. In a third chamber, the gas is then heated, and the sample is ionized by reacting with the metastables and causing desorption.”

A schematic diagram of a DART ion system (Photo Credit: Dr. Chip Cody, as used in Ball’s Thesis Study)

The researchers can use DART with a spectrometer for pinpointing and identifying the unique makeup and pattern of each sample—in this case, a 3D printed polymer used to manufacture a weapon. Ball points out that the process does not harm a forensic sample in any way, meaning that evidence can be stored and explored further, as needed later in a trial. The DART-MS ‘fingerprint mass spectra’ also makes it useful in many other law enforcement applications like drug busts and other criminal activities requiring trace analysis.

A display including 30 of the plastic samples analyzed for this study.

As the researchers expanded their analysis efforts in conjunction with the DART-MS data, they were able to categorize samples by different polymers—followed by analysis of manufacturer and color. Ball emphasizes the importance of this work for law enforcement officials in the future as they could have greater luck in identifying crimes that are gun-related, requiring further evidence for trials and convictions. Samples were taken from 50 different types of 3D printing polymers, including PLA, ABS, PETG, nylon, and more.

While the second part of the study was not related to 3D printing, Ball was engaged in creating other analytical sampling devices, with the use of a Direct Mercury Analyzer. Find out more about that study and the mechanics of measuring mercury and toxicity levels here.

“The results from this study show strong potential for the classification and identification of unknown polymer evidence as the 3D-print polymer database continues to grow,” reports Ball in the conclusion of his thesis. Chemometric analysis of mass spectral data allowed for the successful classification of various 3D-print polymer samples, and thermal desorption techniques provided an even stronger basis for this classification. It is recommended that another full study be done in the future, with a focus on modifying the parameters used in the chemometric analysis of polymers for potentially stronger separation when generating PCA plots.”

Most of the 3D printing realm is uncharted territory, and as soon as the technology hit the mainstream, designers, engineers, and a multitude of creative users around the world were left to think up an infinite amount of ways to ‘change the world’ – and get in some trouble too. Weapons of course were high on the list for enthusiasts to take a stab at, whether in creating replicas for cosplay, creating gun designs and advocating, or bikers 3D printing guns in Australia to promote crime endeavors. It’s not likely that 3D printers are going to take over as the manufacturing technique of choice, but users are curious about what they can do, and weapons enthusiasts are often very passionate about their guns and different ways to construct, and enjoy them.

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Direct analysis of 3D-Print Polymer

Thermal Desorption unit coupled to DART source at the MS inlet

[Source / Images: Development of a Dart-Mass Spectral Database for 3D Printed Firearm Polymers, and Airborne Mercury at Three Lakes in North Mississippi]

Istanbul: Thesis Student Explores Continuous Fiber Composites in FDM 3D Printing

Although polymers are still the most popular materials used in 3D printing today, many users find themselves limited due to issues with inferior strength and rigidity. Creating composites is a good way to solve these problems, allowing manufacturers to enjoy the benefits of existing plastics while reinforcing them for better performance. In ‘Modelling and path planning for additive manufacturing of continuous fiber composites,’ Suleman Asif, a thesis student at Sabanci University (Instanbul), examines how the addition of continuous fibers can improve fabrication processes with thermoplastic polymers, and add greater strength in mechanical properties.

FDM 3D printing is mainly explored here. Issues with FDM 3D printing and these materials, however, tend to be centered around a lack of strength and inferior surface finish, build times that take too long, and inconvenient post-processing. In previous studies, researchers have used short fibers to strengthen thermoplastics, along with carbon nanotubes and fiber composites. Iron and copper have been added to ABS, and the addition of graphene fibers have been noted to add conductivity. In most cases, tensile strength increased but there were issues with interfacial bonding and porosity.

The use of short fibers and nanofibers has been explored, but Asif explains that such additions are better for applications like aerospace or automotive. With the use of continuous fiber reinforced thermoplastic (CFRPT) composites, though, both ‘ingredients’ are extruded at the same time from one nozzle and show significant improvement and strengthening.

Schematic diagram of 3D printing process with continuous fiber composite

In a different study, researchers loaded both thermoplastic polymer and continuous fibers into the nozzles for FDM printing, with PLA and continuous fibers (some samples consisted of carbon fibers, and some with jute) added separately to another nozzle. While carbon did offer improvements in strength, the jute was not helpful due to ‘degradation of fiber matrix interactions.’ Other tests showed that PLA reinforced with modified carbon showed higher tensile and flexural strength values, demonstrating how powerful ‘preprocessing’ can be.

“Furthermore, a path control method was developed to print complex geometries including hollow-out aerofoil, a unidirectional flat part, and a circular part,” states Asif.

Previous methods also used ABS and carbon fibers, with two different nozzles and the carbon fibers contained in between the upper and bottom layers of the plastic.

“The process worked in such a way that after printing of lower layers of ABS, carbon fibers [were] thermally bonded using a heating pin before the upper layers of ABS were printed. In addition, some samples were also thermally bonded using a microwave to understand the difference between both methods,” said Asif.

In comparison to pure ABS, the results demonstrated significant strengthening in mechanical properties.

“In addition, it was observed that there was not much difference between the results obtained from test specimen thermally bonded by heating pin and microwave oven. So, it was concluded that microwave could be successfully used for thermal bonding between matrix and other fiber layers.”

Researchers also attempted to reinforce PLA with aramid fibers, showing ‘notable enhancement.’ Another test evaluated a raw material of commingled yarn, containing polypropylene (PP):

“A cutting device was also incorporated in the system, and a novel deposition strategy was developed. The results showed a remarkable increase in flexural modulus as compared to pure PP. However, the void presence in the samples was a major issue in the proposed technique.”

Overall, in reviewing the multitude of studies performed, Asif saw potential for improving mechanical strength, but realizes a need for control of the fiber position within the nozzle to reduce adhesion issues.

“The system also needs to be designed in such a way that the fiber lies directly in the center of the nozzle to ensure that the thermoplastic polymer is properly diffused into the fiber from all sides using a coaxial printing process in which more than one materials are extruded simultaneously through a nozzle along a common axis,” says Asif.

The researcher also began examining various path planning processes for acquiring point locations that guide the extruder in depositing materials for filling layers. Asif discovered that most suggested path planning was limiting as it only worked for specific complex structures—some of which would not be appropriate for fabrication of CFRTP composites. Asif suggests that as the algorithms stand currently, there would be problems due to:

Under-deposition (typically called underextrusion in FDM)
Over-deposition
Movement of the extruder to next layer after filling one layer

Coaxial CFRPT printing and composite structure with unit cell

“Hence, there is need of a continuous path planning method that can generate a deposition path without any under-deposition and over-deposition, and with better moving strategy from one layer to the next one,” concludes Asif.

“As a future work, a screw-based mechanism can be designed and developed for 3D printing of CFRTP composites. It would allow the continuous input of thermoplastic pallets and, therefore, parts with large dimensions can be printed. In addition, a topology optimization based algorithm can be developed to control the number of layers containing fibers to produce optimized lightweight parts depending upon specific load applications.”

3D printing offers an infinite amount of opportunity for designers and engineers around the world, immersed in creation—whether that is industrial, artistic, or completely scientific. There is an immense amount of energy centered around this technology that just continues to grow in popularity, and especially as users continue to refine the processes and materials. Composites are often used to strengthen existing methods and materials, whether in making structural parts for aerospace , regulating electrical composites, or studying conductivity and different techniques for fabrication. Find out more about the use of continuous fiber composites here.

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Effect of nozzle diameter on the elastic modulus of continuous fiber composites

Implementation of the developed algorithm on a commercial printer (a) Complex concave geometry (b) Fidget spinner

[Source / Images: ‘Modelling and path planning for additive manufacturing of continuous fiber composites’]

Thesis Focuses on Using Cooperative 3D Printing with Robots to Improve the Technology’s Scalability

Illustration of the slicing strategy for cooperative 3D printing.

Obviously, the size of your 3D print is limited to the size of your 3D printer…you wouldn’t try and 3D print a building, no matter how small, using a desktop system, right? Jace J. McPherson from the University of Arkansas put it more exactly in the honor’s thesis he wrote and submitted for his Bachelor’s degree in Computer Science and Computer Engineering:

“More specifically, an object cannot be printed if it is wider than the full horizontal movement range of an extrusion nozzle or if it is taller than the maximum height of the extrusion nozzle above the printing surface (i.e., the “print bed”).”

Chunker results with a cylinder and a car model.

According to McPherson’s thesis, titled “A Scalable, Chunk-based Slicer for Cooperative 3D Printing,” print jobs’ size limitations can hinder the technology’s goal of being “fully dynamic.” In the thesis, he focused on the issue of 3D printer scalability – limited by print bed size and use of a single printhead – and lack of manufacturing automation, and the idea of cooperative 3D printing, and a new slicing strategy for this technology, as a combined solution.

The abstract states, “Cooperative 3D printing is an emerging technology that aims to increase the 3D printing speed and to overcome the size limit of the printable object by having multiple mobile 3D printers (printhead-carrying mobile robots) work together on a single print job on a factory floor. It differs from traditional layer-by-layer 3D printing due to requiring multiple mobile printers to work simultaneously without interfering with each other. Therefore, a new approach for slicing a digital model and generating commands for the mobile printers is needed, which has not been discussed in literature before. We propose a chunk-by-chunk based slicer that divides an object into chunks so that different mobile printers can print different chunks simultaneously without interfering with each other. In this paper, we first developed a slicer for cooperative 3D printing with two mobile fused deposition modeling (FDM) printers. To enable many more mobile printers working together, we then developed a framework for scaling to many mobile printers with high parallel efficiency. To validate our slicer for the cooperative 3D printing process, we have also developed a simulator environment, which can be a valuable tool in visualizing and optimizing a cooperative 3D printing strategy. This simulation environment was also developed to export the visualization in a generic format for use elsewhere.”

Large-scale cooperative 3D printing. Many robots cooperate to produce a single object that does not require assembly upon completion. The final product in this figure is a topographical map of the state of Arkansas.

Cooperative 3D printing is made up of multiple independent, free-roaming robot 3D printers that receive instructions on how to print one part, or chunk, of a whole object. The mechanism makes it possible to autonomously complete large print jobs, with no interruptions, in a single piece, without human interaction. The parts are actually 3D printed on top of each other so they’re joined during the process and not after.

(a) Illustration of the chunk’s dimensions and printing limitations on the slope, and (b)a comparison of chunk width with robot width.

“Cooperative 3D printing solves physical scalability with the premise that multiple independent 3D printers can be used to produce a single object. These printers need to “cooperate” to produce objects that would normally exceed the size limitation of a traditional 3D printer. They must have the freedom to navigate a large area, such that their print range is limited only by the size of the print surface, as opposed to a fixed range imposed by the extrusion nozzle’s mechanism. To summarize, assuming the print surface is easy to scale, the potential print size will also be highly scalable,” McPherson wrote.

“This new mechanism also solves time scalability assuming new 3D printers that enter the fray can decrease the overall print time. Given that the number of printers is dynamic, we can quantify the time scalability as a function of the parallel efficiency from using any number of robots.”

The chunker design subdivides 3D models into chunks, which are then split up between the robots for 3D printing. The slicer converts these chunks into print commands for the robots, and the simulator creates a visual, using the slicer commands, that shows how real robots would complete their tasks. It’s important for the simulator to be properly designed, as it’s used to validate the chunker and slicer algorithms – if the simulator is not accurate, the rest of the process isn’t either.

In the rest of his thesis, McPherson describes how the slicer makes it possible to subdivide models so that chunks can be 3D printed in parallel, as well as demonstrating how to scale the slicer for more than two robots for additional degrees of spatial freedom.

“Results show that the developed slicer and simulator are working effectively,” McPherson wrote.

McPherson hopes that this project can help “lay the foundation for scalable Cooperative 3D printing,” which could open up a whole new direction of research for scaling 3D printing, and potentially even “revolutionize the way manufacturing processes are structured.”

“This thesis has presented, in detail, a feasible process for managing ?? 3D printing robots operating in parallel on a single print job, taking into account the geometric constraints, the communication requirements between robots, and the necessary pre-processing needed to properly subdivide a model for chunk-based printing,” McPherson concluded.

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Student Takes A Look at Several Metal 3D Printed Antennas for Thesis Paper

In a thesis entitled “Design of Microwave Components using Direct Metal Laser Sintering,” a Waterford Institute of Technology student named Deepak Shamvedi discusses using 3D printing to fabricate several microwave components, including the first-ever 3D printed metal Sierpinski gasket antenna, with multiple resonance characteristics. Shamvedi chose the Sierpinski gasket antenna because of its complexity, aiming to “push the limits of 3D metal printing.”

The antenna was 3D printed using the EOSINT M280 machine and a titanium alloy called Ti-6Al-4V.

“Following the rules of 3D printing, one should acknowledge that even though the Sierpinski fractal design may look simple, but it is complex at the same time,” states Shamvedi. “It consists of an arrangement of stacked pyramids one-upon-another, to form a 3D geometry. A rectangular copper clad PCB ground plane, of 160 mm x 100 mm, with 1 mm thickness, has been used to serve as a finite ground plane to the printed antenna.”

Because the 3D printed version of the antenna could not be realized with infinitely small joints, Shamvedi had to print it in an upside down orientation with a minimum of 1.90 mm base diameter (0.95 mm base radius). This value was chosen to achieve the 3D design without any metal drooping. The base diameter also needed to be big enough to facilitate soldering if needed. The base diameter of the antenna formed a ring-like shape, due to which the effect of the RF performance of the antenna, from increasing or decreasing the width of the ring, has been named the “ring width effect.”

Support structures were required; in order to make them easier to remove, Shamvedi added small holes in the CAD design of the supports. Once the antenna was 3D printed, it underwent a rigorous post-processing routine to remove the supports and reduce the surface roughness of the component. The antenna was then mounted onto feeding circuitry for RF measurements, which were carried out after each stage of post-processing, including wet blasting and polishing, to assess the affect of the surface roughness on the antenna’s performance.

“From the results obtained, increased surface roughness increases the random scattering of electromagnetic waves; therefore, increasing RF resistance, which further reduces the gain of the antenna,” explains Shamvedi. “The antenna RF performance was measured and found to be in good agreement with simulation results, in terms of bandwidth and radiation characteristics.”

Experimental prototype of a monocone antenna

Shamvedi also 3D printed a monocone antenna and integrated an N-type feed onto it to create a monolithic structure. 3D printing, he explains, produces fine detail and robust components with low surface roughness. A monolithic structure can also offer better mechanical properties over glue or solder. Despite some challenges, Shamvedi was able to produce a working prototype of a 3D printed antenna, and the measured RF results for the antenna were found to be in good agreement with the CST simulation results.

Shamvedi then compared the performance of three metal 3D printed antennas to that of polymer ones. A metal 3D printed inner lattice antenna possessed higher strength-to-weight ratio than a metal-coated polymer antenna. He also investigated the effects of surface roughness on a 3D printed metal horn antenna, and explored 3D printing as a means to improve the performance of an X-band horn antenna, with the primary goal of side-lobe reduction. Finally, he 3D printed an artificial dielectric lens for applications including 5G.

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Thesis Provides Proof of Concept for Using 3D Printing to Improve Design of Internal Pressure Relief Valve

Test pumps installed on 75 HP dynamometer: Test Setup Discharge Port at 90°

Over the years, 3D printing has proven to be a pretty handy technology to have in one’s toolbox when it comes to making replacement and mechanical parts, like hand water pumps, transmissions, gears, and valves. For his Master’s of Science thesis this year, titled “3D printed relief valve analysis and validation,” John Anthony Dutcher, III, a student at the University of Northern Iowa‘s Department of Technology, used SLA 3D printing to fabricate prototypes of the internal pressure relief valve of a positive displacement pump.

The abstract states, “Additive Manufacturing allows for faster, lower cost product development including customization, print at point of use, and low cost per volume produced. This research uses Stereolithography produced prototypes to develop an improvement to an existing product, the internal pressure relief valve of a positive displacement pump. Four 3D printed prototype assemblies were developed and tested in this research. The relief valve assemblies consisted of additive manufacturing produced pressure vessel components, post processed, and installed on the positive displacement pump with no additional machining. Prototype designs were analyzed with Computational Fluid Dynamic simulation to increase flow through the valve. The simulation was validated with performance testing to reduce the cracking to full bypass pressure range of the valve. By reducing this operational range of the valve, the power requirement of the pump drive system could be reduced allowing for increased energy efficiency in pump drive systems. Performance testing of the 3D printed relief valves measured pump flow, poppet movement within the valve, and discharge pressure at operational conditions similar to existing applications. The Stereolithography prototype assemblies performed very well, demonstrating a 56% reduction in the pressure differential of the cracking to full bypass stage of the valve. This research has demonstrated the short term ability of additive manufactured produced components to replace existing metal components in pressure vessel applications.”

The gear found inside positive displacement pumps, developed over a century ago, was able to overcome existing performance limitations, but it was by no means perfect. These pumps need an internal relief valve, which provide protection against too much pressure; if there’s a reduction in discharge flow, the over-pressure system could fail.

“The primary focus of this research is to investigate the performance of an internal relief valve for a positive displacement pump, propose an improvement to flow conditions in the cracking to full bypass pressure range of the valve based on flow simulation and validate the performance improvement with 3D printed prototypes,” Dutcher wrote.

SLA Part Production

Over the years, the design of the internal relief valve in these positive displacements pumps has not changed much. But by using computer simulation, the design can be revised and optimized to make the part more efficient. As he wrote in his paper, Dutcher’s research validates the 3D printed prototypes, using Computational Fluid Dynamics simulation and perfrmance testing, “in the design development of an improvement to an existing product,” and also shows that costs and time can both be reduced by using 3D printing to manufacture the valve.

“Additive manufacturing has the benefit of customization, allowing for design changes,” Dutcher wrote.

“Developing customizable end use components that can manufactured at the point of use, allows for application specific products to be produced for pressure vessel applications.”

The valve prototypes, 3D printed using SLA technology, were shown to reduce the amount of cracking in order to fully bypass the stage differential pressure that’s necessary to operate the internal relief valve. FDM 3D printing was used to make mounting brackets to attach an LVDT sensor to the valve prototypes; this sensor measures the movement of the poppet (internal device in the relief valve that seals its surface) during testing.

Assembled Reference Valve Extended

In his thesis, Dutcher wanted to determine if 3D printing could successfully be used to produce components of a test valve for the positive displacement pump, if the valve’s geometry was able to be optimized to reduce cracking based on flow conditions, and if the 3D printed prototype valves would perform at the same level as existing ones made with conventional methods of manufacturing. Ultimately, while he did answer these questions and demonstrated that 3D printing does indeed have applications in developing new products, his research provided a viable proof of concept for improving the existing design of a product.

“The 3D printed prototypes were developed to reduce cost and delivery lead time for prototype testing,” Dutcher wrote.

“The flexibility in design permutations that additive manufacturing allows with customization provides the opportunity to validate multiple product designs in parallel.”

SLA Support Structures

By using 3D printing to create the prototypes, Dutcher was able to develop several different design concepts at the same time, without getting caught up by the normal barriers that come with traditional manufacturing methods. SLA 3D printing also makes it possible to produce parts with “the dimensional tolerances of machined components,” which helps speed up the development of prototypes.

“This research has demonstrated the SLA 3D printing’s ability to reproduce existing machined metal components,” Dutcher concluded. “While extended performance testing was not the intent of this research, the 3D printed pressure vessel valve components performed very well in performance testing. The development of the design variations in timely manor would not have been possible without Additive Manufacturing. Testing has shown an improvement in the valve performance by reducing the cracking to full bypass pressure from 52.0 psi to 22.8 psi. The successful performance test to improve an existing product demonstrated the validity of the SLA 3D printed prototype assemblies.”

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