Tag Archives: 3d printing

3D Printed RF Components

Most RF system designers view air simply as a medium for electromagnetic energy propagation from the source to the receiver. This is usually the case, allowing them to focus the bulk of their design effort on interconnections and integrated circuits that define the physical system.

However, that is only a simplistic view, as other properties of air are also important. For instance, air can keep electronics cool with convection, and it has dielectric properties that some RF components find critical.

Heinrich Hertz first demonstrated wireless signals in 1888. He energized a spark gap of 1 millimeter using high voltage, creating a wideband pulse. A dipole antenna transmitted this pulse. The antenna had two collinear metal rods with capacitive metal plates. At standard atmospheric conditions, air has a dielectric strength of about 30-70 volts/mil or 3-7 kV/mm. Discharged through air across the gap, the high voltage spark caused brief standing waves of oscillating current in the antenna, which then radiated this energy as a brief pulse of radio waves.

With the growth and maturing of wireless, RF tuners often had variable capacitors. These consisted of multiple parallel plates with air gaps that decided the capacitance value of the tuning assembly. By rotating a shaft, it was possible to adjust the position of the moving plates with reference to the static ones, thereby changing the capacitance between them from near zero to several hundred picofarads.

Vacuum has the ideal unit dielectric constant, while air is very close, with a value of 1.00058986. In comparison, the dielectric constant of PTFE is 2.0, and for FR4 it is about 4.4.

Another important property of vacuum, is its dielectric loss, dissipation factor, or loss tangent is zero, and so it is for air as well. Moreover, air characteristics are stable well into the terahertz frequency range, but it is not so for other dielectrics.

However, both vacuum and air have a common weakness. Neither has any structural strength. Therefore, they require a supporting form to hold them. Engineers find this a challenge as there must be an adequate amount of air within the structural medium of the dielectric.

The solution to this problem lies in using AM or additive manufacturing, also known as 3D printing, along with foam, and a family of photopolymer materials. Roger’s Corp typically supplies specialty RF materials, such as the Radix family of 3D printable, high-resolution materials. Radix is a photo-curable, highly viscous resin. It is a high filler concentration that offers good mechanical and electrical properties even at high frequencies.

3DFortify, of Boston, makes a particular type of Flux Core 3D printer. This is the only printer in the market that can effectively print using the Radix resin. The two companies are now partnered to produce 3D-printed RF components.

The printer layers the material with a thickness of less than 100 µm and cures it with a UV digital light processing projector in one flash for every layer. They provide both metalized and non-metalized versions. With the 3D-printing approach, the manufacturer can vary the structural strength of the material as necessary. They can give thick and strong structures at places subject to physical pressure or connections. 

3D Printing and Electricity from Waste Heat

There are several techniques existing for recovering energy from waste heat. The typical approach is to use waste heat to generate electricity. Now 3-D printing methods are taking the lead to make devices that will convert waste heat into electricity.

UNIST is located in the largest industrial city of Ulsan in Korea. Engineers there have conducted breakthrough research. They have developed a new thermoelectric technology for producing power-generating tubes. The best part of their research is they can print the tubes using 3-D printing methods.

Most automobile and industrial exhaust gases generally go to waste. But they are usually hot. By generating electricity from these hot exhaust gases, it is possible to enhance the efficiency of fossil energy production techniques. For this, the most suitable method is to use thermoelectric or TE methods. However, this is not an easy task, as typical thermoelectric products that the traditional processes produce are neither cost-effective nor do they fulfill efficiency requirements. According to the researchers, exhaust pipes fall into this category.

Engineers addressed this inefficiency issue by creating a special type of exhaust pipe. They built it out of lead and tellurium and used 3-D printing techniques for creating it. According to the researchers, they created the ink for the 3-D printer by mixing metal particles with a glycerol solvent. This provided them with the necessary viscoelasticity necessary for the ink and gave the ink the necessary characteristics of elasticity and viscosity.

The tube printed with this ink offers a high thermoelectric performance between temperatures of 400 and 800 °C. Most exhaust gases from vehicles exhibit this range of temperatures.

The research was a joint venture between the Department of Mechanical Engineering, UNIST, and the Department of Materials Science and Engineering, UNIST.

With their computational and experimental findings, the researchers have demonstrated the efficacy of their 3-D printed TE tubes they made from PbTe for power generation from waste heat. Their design has proven to be a system-adaptive and high-performance thermoelectric generator.

The 3-D printed power-generating PbTe TE tubes are made of p-type material and n-type material, with insulating material separating them. The TE tube has a series of p-type PbTe tubes followed by an insulating tube, and an n-type tube repeating many times. One complete power-generating TE tube may have ten pairs of p-type and n-type PbTe tubes in series.

According to the lead researcher, this 3-D printed power-generating PbTe TE tube technology can efficiently convert waste heat escaping through factory chimneys into electricity. In fact, factory chimneys are the most common type of source of waste heat. The shape of the tube makes it very effective for collecting heat as compared to the conventional rectangular shape of present TE generators.

Using 3-D printing technology for producing thermoelectric materials overcomes the limitations that engineers typically face while using commercial materials. According to the researchers, other fields can also use the viscoelastic characteristics that 3-D printed materials offer. The publication Advanced Energy Material features this novel and innovative research in thermoelectric materials.

3-D Printed Electronics

Today, 3-D printing is the most popular technology among all manufacturing and prototyping methods. However, 3-D printing is not new. In the 1980s, a company filed a patent for 3-D constructing models using stereolithography. Such patents have been instrumental in holding back the development, manufacture, and distribution of 3-D printing technology, until now.

3-D printing typically works by slicing a 3-D design into several small horizontal 2-D sections and then splicing them together by printing each 2-D slice atop the other. 3-D printers commonly use a thermoplastic wire wound on a reel. The printer extrudes this wire through a hot nozzle. There are 3-D printers that build models from paper. They cut out each layer from the paper, and glue one layer to the next. Other, more advanced systems sinter metallic dust using lasers.

It is possible to use 3-D printing technology for manufacturing electronic components. This uses a printer and an additive process. However, not all see the 20-D printed electronics as being actually 3-D printed. For instance, although they consider transistors as 2-D, in actual practice, they are 3-D, requiring both additive and subtractive processes to build up their insulating layers, source and gate terminals.

For now, there is little practical application for most 3-D printed electronics, and their use in the real world is rare. This is so because manufacturing electronics in the traditional manner is much easier, cheaper, and more reliable. Still, there is a significant amount of research for trying and creating practical devices with 3-D printing technology. So far, there has been significant success in printing transistors, capacitors, diodes, and resistors using 3-D processes.

Although electronic components may use several materials, 3-D printed devices generally use graphene or other organic polymers. Researchers use graphene, as it gives them the ability to create narrow channels and gates while allowing doping. It is easy to dispense organic polymers in solution form, which is ideal for using them in inkjet printers.

However, with printed electronic capabilities still far removed from standard electronic systems, it is rare to find commercial applications for printed electronics. However, there is plenty of research going into printing them.

Being still in their infancy, printed electronics are presently found only in research labs, or in prototypes. There are two technologies popular, tending towards practical—Pragmatic and Duke University.

A UK-based company, Pragmatic, produces printed electronic components for one-time applications. These are disposable electronic items like RFID tags. The most significant feature of Pragmatic devices is they use a flexible substrate. They cover all essential components like resistors, capacitors, and transistors. Although Pragmatic has not fully demonstrated a functional device, they have produced ARM core processes, claiming each device consumes 21 mW and energy efficiency of 1%.

Presenting the best examples of practical printed electronics, Duke University claims its products exceed the typical life cycle. They use a new method of additive processes for creating printed electronic components like resistors, capacitors, and transistors. Their components are mostly based on carbon, while the construction uses aerosol spraying similar to inkjet technology. They build the insulating layers from cellulose.

Less Expensive 3D Printing

3-D printing is no longer a new technology. Several design studios use it, along with some home users who make their products using 3-D printers. However, the general opinion is it is expensive, slow, and unable to compete with traditional mass-manufacturing processes. Although considered a revolutionary technology, so far, 3-D printing has remained on the periphery.

Now, a Massachusetts company is trying to prove the general opinion wrong. Desktop Metal is coming out with a 3-D metal printing system so fast, safe, and cheaper than any existing system, they claim it will compete directly with the traditional methods of mass manufacturing. In their Studio System, Desktop Metal presented an office-friendly, fully automated sintering furnace that had fast cycle times and a peak temperature of 1400°C. This allowed it to sinter a wide variety of materials.

On one hand, home users and design studios can afford only cheap ABS plastic printing materials on their desktop printers. On the other, organizations such as Boeing and NASA are going for laser-melted metal printing. Overall, the entire process of 3-D printing is very slow, expensive, and unable to scale up or scale down.

Desktop Metal, out of Massachusetts, is headed by a team among who are some that had first thought of additive manufacturing. They claim to have the right technology and machinery that is going to give the necessary impetus to 3-D printing to make it into big time.

Desktop Metal is claiming it can make metal printing reliable and up to 100 times faster than existing speeds and at 10 times cheaper initial costs. By using a much wider range of alloys, they claim they will incur 20 times cheaper material costs compared to the existing laser technologies. In fact, their machines may be the precursors for large-scale 3-D manufacturing.

In reality, Desktop Metal is presenting two systems. One of them is the Studio System and the other a production system. While the production system is meant for mass manufacturers, the studio system offers rapid, cheap metal prototyping aimed towards engineering groups.

The Studio System from Desktop Metal costs ten times lower than its equivalent laser system. It is also many times more safe and practical to keep in an office. Unlike the laser system, the Studio System does not use hazardous metal powders that are sometimes explosive or dangerous lasers. The Studio System may be placed anywhere in the office, as it does not require specialized ventilation installation, nor does it require operators wearing gas masks.

The metals offered by Desktop Metal are usually in rod form, bound with polymer binding agents, and shipped in cartridges. However, almost anything usable in a Metal Injection Molding system is acceptable to the Studio System. That means a wide variety of metal options including aluminum, bronze, copper, a range of stainless steels, 4140 chromoly steel, titanium, Hiperco 50 magnetic, and more than two hundred other alloys.

When running, the printer prints layers of bound metal parts. These have to go through a de-binding bath to remove most of the binding polymer. The parts can then go into the sintering furnace.

3D Printers: Change the Shape of Your 3D-Printed Objects

When you print 3D objects on your 3D printers, they remain stable. Other than deteriorating over time, the objects do not change by themselves. However, that may be changing now. Scientists at MIT have created a new technique of printing 3-D objects where you can change the polymers in the object after printing. That means change the color of the object, grow or shrink it, or even change its shape entirely.

Associate Professor of Chemistry at MIT, Jeremiah Johnson led the research, along with Postdoc Mao Chen, and graduate student Yuwei Gu. They have written a paper on the findings, and they call the technique living polymerization. According to the team, the process creates materials whose growth can be stopped and started at will.

As they explain, after printing the material, it is possible to morph it into something else using light, even growing the material further. For instance, the team used a 3-D printed object immersed inside a solution. When they shined Ultra Violet light on the object, while it was still immersed, the resulting chemical reaction released free radicals. The free radicals bound themselves to other monomers within the solution and added them to the original object. According to the team, the process was highly reactive, and damaged the object.

At another study at the Wyss Institute for Biologically inspired Engineering of Harvard University, Dr. Jennifer Lewis is a senior author on a study on shape-shifting objects created using a 3-D printer. The team has devised a technique that allows printed objects to change their shape according to the environment.

According to the researchers at Wyss Institute, the printer creates a structure that can shift its shape. For instance, when immersed in water, the structure folds into complex and beautiful designs. The researchers claim they can adapt the process so that the printed object can fold into prescribed shapes when cooled, heated, or injected with an electrical current.

The researchers are of the opinion the technology could pave the way for generating new types of medical implants. Folding into shape when inserted into the body, such implants could generate a new family of soft electronics. According to Dr. Lewis, this is an elegant advance in the assembly of programmable materials, which a multidisciplinary approach made it possible to achieve. This has taken them farther than merely integrating form and function for creating transformable architectures.

The researchers have published their work in the journal Nature Materials. They say they were inspired by the manner in which plants grow and change their shape over time, as plants and flowers contain microscopic structures as tissues allowing them to change their shape as their environment changes. For instance, depending on temperature and humidity, plant leaves, flowers, and tendrils open or fold up.

Dr. Lewis used a printable hydrogel as it swells when added to water. The team designed specific structures under control that would change shape when placed in water. They derived the hydrogel ink from wood, and the ink had cellulose fibrils very much like the structures in plants that allow them to change shape.

3D Printer based on the Raspberry Pi

3D printers are becoming so very popular now and you can get them in many different sizes and configurations to suit your purpose. AON, a company providing 3D printer services in Montreal has built a prototype of a high-end dual extrusion 3D printer. A notable feature about this printer is the huge build volume of 129,600 cubic centimeters, which users can heat up to 70°C. However, most importantly, the device has an SBC that runs it – a Raspberry Pi or RBPi running the open source Linux Operating System and a 3D printer host software named OctoPrint.

AON was frustrated with the limitations of dual-extrusion printers available. They had to contend with limited build volumes, high failure rates and warped and cracked products. AON decided to address the above problems by building their own 3D printer. The result was an RBPi based high-end, 3D printer with a huge build area – 18x18x12 inches or 45x45x64 cm.

Estimated at an eventual retail price of US$4,000, the AON 3D printer (still a Kickstarter project) may not exactly be an impulse buy, since consumer 3D printers are available from $300 onwards. However, the discount price for this fascinating printer finds favor in a write-up in the 3Ders.org website.

The AON 3D printer makes use of FDM, or Fused Deposition Modeling. This is a thermoplastic extrusion technology and most other 3D printer manufacturers such as the MakerBot Replicators use it. However, the difference is AON offers dual extruder heads that operate independently.

Users printing a complex object can speed up the printing by using both extruders simultaneously. Alternatively, printing of two identical designs is possible using the same or different colors or filament materials. To prevent waste of plastic oozing from a temporarily inactive extruder, the user can park the extruder off to one side.

To heat the chamber up to 70°C, the AON 3D printer uses its 1800W heaters. AON claims this helps to reduce cracking and warping with use of high-end materials such as Polycarbonate, Nylon or ABS. The printer allows printing with PLA or other special high-temperature materials and eliminates heat creep with special devices. These include high-end E3D Volcano hot ends reinforced with a heat-resistant thermocouple and cooled with water. Another robust feature is the high-end XY gantry that can travel at 500mm/s on the XY axis.

The printer, with a size of 80x90x125cm, integrates an Azteeg X3 Pro controller board. This features SD8825 SureStepr motor drivers and the Wi-Fi enabled RBPi. According to AON, the price includes the preloaded OctaPrint and a license for a copy of the Simplify3D printer software.

As the RBPi is Wi-Fi enabled, users do not need to tether a laptop. They can use any web browser to link to OctaPrint, which runs on the RBPi or any other embedded Linux board, supporting a huge variety of 3D printers. All usual print control features are available with the web interface, and this includes uploading and previewing the gcode files. Users can also configure custom controls. Remote visual monitoring via a webcam is possible, including remote temperature monitoring.

A Smart Fridge Tells You What It Wants

Imagine you are at the grocery store and wondering what you need for the next week – if you could only peep inside your fridge now, shopping could be easier. With the new smart fridge from General Electric in your kitchen, you could use a smartphone and ask the fridge what it lacks. The smart fridge will tell you exactly how much beer, soda, milk, and even how many eggs or separate vegetables it is left with. Actually, GE ran a contest taking ideas from users that could be turned into serviceable and manufacturable accessories. They announced the winners at the CES 2015 at Las Vegas. MakerBot Industries, LLC in Brooklyn, NY, is offering not only a MakerBot Replicator, but also a 3D Printer that allows engineers, traditional product designers and even consumers to prototype their ideas rapidly. Successful designs will be manufactured at FirstBuild at their microfactory in a fraction of the time it normally takes.

GE’s ChillHub is the first major home appliance that consumers can base their prototypes on to make their own accessories for a smart refrigerator. The ChillHub can tell your smartphone how much milk is currently left, because it has a milk weighing arrangement that your phone can query when you are at the grocery store. Besides the milk weighing arrangement, the ChillHub has several USB hubs allowing you to add your own plethora of smart accessories and sensors to let your smartphone see what else you need.

For proof of concept, GE and MakerBot, in collaboration with Thingiverse, came up with the Icebox Challenge, which had about 200 entries. The first-prize winning entry was an Odor-eating Hotshot. It uses a standard box of baking soda, but maximizes its odor-canceling capabilities, keeping track of its presence in the refrigerator and alerting users when to replace it.

The second prize was a bottle holder that helps the user organize different beverages while doubling as a chip-clip that keeps bagged snacks fresh. The third prize was the Butter Pig that dispenses standard butter sticks to simplify cooking in the kitchen, measuring of recipes and making toast.

The ChillHub is suitable for adding third-party accessories because of its eight USB ports. The ports are capable of delivering up to 2A each. That makes it very easy to add accessories that can be accessed from the Internet via their built-in Wi-Fi. GE calls the ChillHub architecture a community-generated product, which is based on an open-source iOS app. This app allows users to easily access the accessories plugged into the USB ports. Other fridge owners can hack their own appliance and make DIY upgrades using the FirstBuild.

FirstBuild community members conceived the design. They used 3D printers as a means of prototyping accessories quickly. The first accessory to be designed was the Milky Weigh that tells how much milk it holds. You can buy the complete Milky Weigh from FirstBuild, or if you are more adventurous, download the entire design and 3D print the components. The Green Bean circuit board from FirstBuild provides the electronics that actually weighs the milk for Milky Weigh.

Raspberry Pi drives photon elephant

You are looking for the best way to control your 3D printer and turn it into a smartprinter. If you are not averse to using a browser-based control panel that will allow you to stream from a webcam, start, pause and resume print jobs while slicing your STL files, you may consider the Photon Elephant.

The Photon Elephant uses the tiny, low-cost, credit card sized, single board computer – the Raspberry Pi or RBPi – to drive the motor controllers of your printer. A conventional SDK or Software Development Kit uses the GPIO pins of the RBPi for the controls. This is all open-source, which means you can tinker with it to your heart’s content. For example, you may want more than what the standard 5-motor controller has to offer. With the Photon Elephant, you can have more time innovating rather than figuring out what makes the firmware tick.

Photon Elephant provides you a bunch of software and hardware based on the RBPi that controls your 3D printer. Printers available in the market typically use an Arduino, without an operating system, to manage the sensors and motors, while the RBPi is used to send it commands. Photon Elephant puts the power of Linux directly into your printer by eliminating the Arduino.

Anyone can build on the simple but powerful Photon Elephant platform. The platform makes it easier to create new and exciting types of 3D printers. Available open source solutions for controlling 3D platforms tend to be out of date and tedious. With the Photon Elephant, the next generation of 3D printers will be more flexible to control.

Entrepreneurs, students, makers and hackers anyone can easily use the Photon Elephant. It handles the entire stack and controls everything from sensors, motors and the User Interface. If you are looking for the simplest solution for getting your printer up and running, Photon Elephant is for you. Additionally, with the Photon Elephant SDK, you have the easiest platform you can build upon.

There is no firmware to be flashed. Use the pre-programmed image on the SD card and plug it in to fire up your RBPi. All you require to do is to connect any compatible printer to the Photon Elephant companion board and you can start using your printer. All the different firmware such as the slicer and printer managers talk seamlessly to one another. Therefore, you simply have to open up a browser on any device and start using the printer over Wi-Fi.

The 3D printing industry is moving forward very rapidly and printers become outdated very quickly. Currently, Photon Elephant is able to support Cartesian RepRap style of printers only. Very soon, Delta printers will also be supported. The SDK is flexible to take on almost any printer methodology.

Flexibility is extremely desirable considering how difficult it is to predict the direction the 3D industry may be taking. There is no sense in spending time in modifying the firmware directly on a chipset as it may become useless by tomorrow. The flexibility of the Photon Elephant SDK helps the user keep up with the industry, as it is very easy to add newer features to the current design