Design News
Back To School Classroom Tech
ESC returns to Minneapolis, Oct. 31-Nov. 1, 2018, with a fresh, in-depth, two-day educational program designed specifically for the needs of today's embedded systems professionals. With four comprehensive tracks, new technical tutorials, and a host of top engineering talent on stage, you'll get the specialized training you need to create competitive embedded products. Get hands-on in the classroom and speak directly to the engineers and developers who can help you work faster, cheaper, and smarter. Click here to register today!
Hydrogel Shows Unprecedented Stretchability, 3D-Printing Capability
Hydrogels are hydrophilic networks of polymeric chains that can retain a large amount of water. Researchers find them useful for many applications—particularly ones that require materials that can withstand large deformations. One challenge to developing hydrogels, however, has been that traditional fabrication methods mainly rely on molding and casting. This has limited the scope of applications by geometric complexity and relatively low fabrication resolution, leading scientists to explore the 3D printing of hydrogels to improve the process—with little success so far, researchers said.
Now, a team from the Singapore University of Technology and Design (SUTD) and the Hebrew University of Jerusalem (HUJI) thinks it may have tackled this problem by developing hydrogels that can stretch in an unprecedented way. This feature opens the door for the use of hydrogels in high-resolution 3D printing to enable a range of applications in soft robotics, transparent touch panels, flexible electronics, and other areas.
Researchers have developed highly stretchable and UV-curable 3D-printing hydrogels that can be stretched by up to 1300 percent and are compatible with high-resolution digital light processing-based 3D printing. This enables the fabrication of hydrogel structures with complex geometries that can be applied to biomedical applications and flexible electronics. (Image source: Professor Qi Ge, Singapore University of Technology and Design)
The hydrogels developed by the researchers can be used in UV curable-based 3D-printing techniques, allowing for the fabrication of hydrogels with more complex geometries at a high printing resolution, said Assistant Professor Qi (Kevin) Ge from SUTD, one of the co-leaders of the project. "We have developed the most stretchable 3D-printed hydrogel sample in the world," he said. "The printed hydrogel sample can be stretched by up to 1,300 percent. At the same time, the compatibility of these hydrogels with digital light processing-based 3D printing technology allows us to fabricate hydrogel 3D structures with resolutions up to 7 micrometers and complex geometries."
The team’s work is a step beyond previous attempts to use 3D printing to fabricate hydrogel structures with complex geometries, including vascular networks, porous scaffolds, meniscus substitutes, and others, researchers said. Indeed, they believe hydrogels are especially well-suited to medical applications because their composition is mainly water, making them biocompatible.
Indeed, Ge said the hydrogels printed by the team “show an excellent biocompatibility, which allows us to directly 3D print biostructures and tissues.” They also possess great optical clarity, making them potentially a good fit for use in 3D-printing contact lenses, he said.
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“More importantly, these 3D printable hydrogels can form strong interfacial bonding with commercial 3D printing elastomers," he added. "This allows us to directly 3D print hydrogel-elastomer hybrid structures, such as a flexible electronic board with a conductive hydrogel circuit printed on an elastomer matrix."
Researchers published a paper on their work in the Journal of Materials Chemistry B. They aim to continue their research to expand the fabrication process and application scope for which the hydrogels can be used.
Elizabeth Montalbano is a freelance writer who has written about technology and culture for 20 years. She has lived and worked as a professional journalist in Phoenix, San Francisco, and New York City. In her free time, she enjoys surfing, traveling, music, yoga, and cooking. She currently resides in a village on the southwest coast of Portugal.
Today's Insights. Tomorrow's Technologies.
ESC returns to Minneapolis, Oct. 31-Nov. 1, 2018, with a fresh, in-depth, two-day educational program designed specifically for the needs of today's embedded systems professionals. With four comprehensive tracks, new technical tutorials, and a host of top engineering talent on stage, you'll get the specialized training you need to create competitive embedded products. Get hands-on in the classroom and speak directly to the engineers and developers who can help you work faster, cheaper, and smarter. Click here to submit your registration inquiry today!
New Polymer Could Serve as a Solid-State Battery Electrolyte
A new polymer that conducts ions at room temperature is showing promise as a battery material for electric cars, consumer electronics, and grid storage systems. The polymer, developed by engineers at Ionic Materials, Inc., could serve as a solid electrolyte—possibly one day acting as an alternative to the conventional liquid electrolytes used in virtually all of today’s lithium-ion batteries. “This will be the first viable solid-state solution for batteries,” Mike Zimmerman, founder and CEO of Ionic Materials, told Design News.
The new material, patented by the company, represents a departure from the status quo in solid-state battery development in that it is a polymer, or plastic, instead of the more common ceramic or glass material. “All of the solutions to date have been ceramics or glasses,” Zimmerman told us. “But they can be brittle and hard to scale up.”
Mike Zimmerman of Ionic Materials: “This will be the first viable solid-state solution for batteries.” (Image source: Ionic Materials, Inc.)
The key to Ionic’s effort is that its material scientists were able to develop a conduction mechanism that allows ions to transfer through the polymer at room temperature. “The most desirable way to incorporate a solid electrolyte into a battery is through the use of plastics,” Zimmerman added. “But it hasn’t been done before because there’s not been a polymer that could conduct ions at room temperature.”
Solid-state electrolytes have been a Holy Grail of sorts for the battery industry for years. Automakers and consumer electronics manufacturers want them because they are inherently safer than liquid electrolytes. They also offer the promise of higher energy density, lower cost, and faster recharge times.
Up to now, however, solid-state batteries have faced numerous challenges, including manufacturability issues. But Zimmerman said that his company’s new material is inherently better-suited to manufacturing than ceramics or glasses. “Because it’s a polymer, it can be scaled into high volume,” he told us. “It can fit into battery manufacturing very easily.”
Zimmerman also says his polymer material would eliminate the overheating and explosion problems notably seen in some lithium-ion batteries, while offering twice the energy density of those chemistries.
The technology is attracting interest from venture capitalists, automakers, energy companies, and even other battery manufacturers. Renault-Nissan-Mitsubishi announced it is investing in Ionic Materials earlier this year, as did Hyundai Cradle, Hyundai Motors’ venture capital arm. Similarly, French-based energy giant Total has invested in the technology. And battery manufacturer A123 Systems is teaming with Ionic on batteries for plug-in vehicles.
RELATED ARTICLES:Zimmerman said he expects the technology to begin ramping into production in about two to three years. One of the keys to that rapid deployment, he said, is its manufacturability. “It’s a solid and it can be extruded,” he told us. “You can make it using any plastics processing.”
Zimmerman will be on hand at the upcoming Battery Show to discuss the solid-state battery in a session titled, "Enabling Solid State Batteries Through Polymer Innovation."
Senior technical editor Chuck Murray has been writing about technology for 34 years. He joined Design News in 1987, and has covered electronics, automation, fluid power, and auto.
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Smart Sensors Make an Impact on Fluid Power
As the industrial environment continues to press forward with the Industrial Internet of Things (IIoT), also known as Industry 4.0, there is one mechanical technology product that has joined the ranks of smart connected devices. The fluid power industry is embracing the world of Industry 4.0 by using smart sensors, which allow hydraulic systems to provide the health status of electrohydraulic machines. In addition, data analytics introduces predictive maintenance practices that allow OEM manufacturers to review system concerns before they can manifest into serve shutdown scenarios.
Shown is a line of wire sensor integrated with a hydraulic cylinder. (Image source: SIKO)
Fluid power is a technology that uses pressurized oil to create mechanical movement. Components such as cylinders, motors, and directional control valves allow this pressurized oil to provide the required forces needed for mechanical movement. The trend to include electronics and hydraulics has intensified with the Industry 4.0 digital factory vision of original equipment manufacturers. As electromechanical systems are improved with the aid of electronics and sensors, hydraulics is using these intelligence-based components for energy efficiency and precision control.
The benefits of adding smart sensors to hydraulic systems include data collection of the health status of fluid power components—machine to machine communications that supports the IIoT or Industry 4.0 smart factories initiatives. Inventory management of hydraulic components can be accomplished using radio frequency identification (RFID) based sensors attached to directional control valves, manifolds, or check valves. With the use of electromagnetic fields, identification tags attached to hydraulic components can aid in streamlining the inventory of such fluid power devices. Also, smart sensor integration with hydraulic components provides a holistic system architecture, which allows adaptability to the interdisciplinary field of mechatronics.
Hydraulic pressure and components can be monitored and inventoried using RFID sensor technology. (Image source: Bestech)
There are a variety of smart sensors for monitoring the mechanical movement of hydraulic components within a fluid power system. Position sensing switches are commonly used to detect cylinder end of stroke motion. To decelerate the cylinder, the position sensing switch detects the end of stroke using a reed or proximity detection device.
These devices are non-contact sensing components. Their operation depends on the disturbance of a magnetic field. With proper signal conditioning, that magnetic field will act as a switch for decelerating the cylinders' extend or retract position. Hall effect switches are another method of detecting the presence of magnetic flux. Upon detection, the small, three pin, solid state device will provide a digital signal that can easily be read by a programmable logic controller (PLC).
The PLC will then control the hydraulics solenoid-controlled check valve, thus restricting fluid flow to the cylinder. For monitoring the rotational motion of a hydraulic motor actuator, rotary encoders are commonly used. The position of the hydraulic motor actuator is determined by the number of digital pulses produced by the encoder or counting disc. This series of digital pulses is sent to the PLC for positional information and control of the hydraulic motor actuator.
The industrial implementation of smart sensors in hydraulics ranges from mobile equipment systems to subsea applications. Lift buckets require proper leveling to ensure safety of the maintenance technician working several hundred feet in the air. Therefore, these specialized mobile equipment systems require linear transducers for proper operation of the hydraulic cylinders, providing positional feedback data to the human machine operator unit.
RELATED ARTICLES:Monitoring the attitude or height of the extended hydraulic cylinder is dependent on inclinometer or tilt sensors for such distance angle measurement devices. The use of gyro-based sensors using microelectromechanical systems (MEMS) provides angle positional data from the inclinometer. As with all smart sensors used with hydraulics, the sensing components along with the electronics are encapsulated and hermetically protected in a stainless-steel housing.
In addition, smart sensors are allowing the vital health status data of hydraulic components and systems to be obtained easily with wireless communications. Bluetooth Low Energy (BLE) technology deployed in mobile devices allows data collection from embedded smart sensors to obtain temperature, pressure, and vibration data wirelessly. The performance of a hydraulic valve can be optimized and tuned using this low power communication technology aided by smart sensor technologies. Additional information on smart sensors and IoT technologies can be obtained from Deloitte Insight’s website.
Rotary encoders can determine the position of hydraulic motor actuators using a digital disc. (Image source: Leine and Linde)
The PTK29 Positilit inclination can measure ±180° tilt angle in one axis of lift motion. (Image source: ASM Sensors)
Don Wilcher is a passionate teacher of electronics technology and an electrical engineer with 26 years of industrial experience. He’s worked on industrial robotics systems, automotive electronic modules/systems, and embedded wireless controls for small consumer appliances. He’s also a book author, writing DIY project books on electronics and robotics technologies.
Wheelchair Users Call for More Innovative Mobility Devices
A new survey is prompting wheelchair users to call for more innovation to help them fulfill their potential in the workplace.
The survey, commissioned by the Toyota Mobility Foundation, showed that 92% of respondents have had problems working or finding a job as a direct result of their wheelchair and 36% have been unable to work at all for the same reason. The foundation is calling on engineers and designers, as well as software and data science experts, to find better solutions for people with lower-limb paralysis.
“The challenge is to start thinking beyond the status quo,” August de los Reyes, a director of user experience on the Search, Assistant, and News Ecosystem at Google, Inc., told Design News. “There’s a great opportunity to innovate in this space, whether it’s at the component level, the device level, or in the entire system of transportation.”
The survey painted a stark picture of the work-related problems facing wheelchair users. It noted that wheelchairs and other types of so-called “mobility devices” limited the number of jobs for which users could apply. Approximately a quarter of respondents said they had to become self-employed and 26% said they had to work at home as a result of their wheelchair use.
The Toyota Mobility Foundation wants to change that—not only through the survey, but also by launching a $4 million global challenge for engineers and designers. Known as the Mobility Unlimited Challenge, it will award $500,000 to five finalists to take their concepts to the prototype stage. It will also award $1 million to help bring the winning product to market. The organization has called for entries to be submitted by August 15, 2018 and plans to unveil the winning concept in Tokyo in 2020.
de los Reyes, who serves as a global ambassador for the challenge, said that the goal is to develop better solutions and to raise greater awareness of the need for innovation. The need to innovate is critically important, he said, not only for the 65 million people worldwide who use wheelchairs, but also for the societies that can benefit by making wheelchair users more productive. “The talent pool of people with disabilities is largely untapped,” he said. “Part of the reason it is untapped is because today’s assistive technologies don’t provide, and sometimes actually prevent, people in wheelchairs from accessing opportunities.”
Beyond the ‘Chair on Wheels’
de los Reyes, who is a wheelchair user, compared the state of innovation in wheelchairs to that of the “horseless carriage” market of the early 1900s. Early automobiles were limited by the vocabulary and mental models surrounding them, he said. Similarly, today’s mobility devices have been limited by the idea that all solutions must involve a “chair on wheels.”
August de los Reyes of Google: “There’s a great opportunity to innovate in this space, whether it’s at the component level, the device level, or in the entire system of transportation.” (Image source: August de los Reyes)
The Mobility Unlimited Challenge will encourage engineers and designers to go beyond such limitations. As such, de los Reyes said, developers are urged to think creatively in the areas of material science, electronics, data science, machine learning, and artificial intelligence, among others.
“I would challenge them to think outside the box and beyond the chair,” he said. “Even beyond the exoskeleton.”
As potential innovation examples, de los Reyes cited the use of sensors to locate potholes and unexpected curbs on sidewalks, thereby enabling users to steer around those hazards. Also, the development of lighter weight portable ramps could enable wheelchair users to more easily traverse stairways. And better batteries could help cut the weight of wheelchairs. Today, he said, portable ramps weigh upwards of 100 lbs and powered wheelchairs can be 500 lbs.
He encouraged engineers to employ the best tools at their disposal to conjure up newer and better ideas. “Introducing artificial intelligence and machine learning within a system of actuators and motors could provide new opportunities for mobility,” de los Reyes said.
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Often, such innovative new ideas end up benefiting everyone, not just those in wheelchairs, de los Reyes said. “If you look at the curb-cuts in cities, people walk their bikes and baby strollers up them,” he said. “Everyone uses them, even though their original intent was for people in wheelchairs.” Similarly, he noted, delivery drivers and countless commuters make wide use of automatic door openers that were originally intended for wheelchair users.
de los Reyes hopes that a new crop of innovative solutions will have a similarly broad benefit. “This is an urgent call for innovation, not only to help the people who can’t access their opportunities, but also to help economic productivity worldwide,” he said.
Senior technical editor Chuck Murray has been writing about technology for 34 years. He joined Design News in 1987, and has covered electronics, automation, fluid power, and auto.
Today's Insights. Tomorrow's Technologies.
ESC returns to Minneapolis, Oct. 31-Nov. 1, 2018, with a fresh, in-depth, two-day educational program designed specifically for the needs of today's embedded systems professionals. With four comprehensive tracks, new technical tutorials, and a host of top engineering talent on stage, you'll get the specialized training you need to create competitive embedded products. Get hands-on in the classroom and speak directly to the engineers and developers who can help you work faster, cheaper, and smarter. Click here to register today!
Carbon Nanotube-Based Fabric Could Double as Charger for Electronics
Researchers already have developed clothing that can harvest and store power for recharging devices on the go. In doing so, they've mainly harvested energy from sources such as one’s own body motion or the sun. Now, researchers from the University of Cincinnati (UC), working with Wright-Patterson Air Force Base, are working to develop clothing for this purpose using a different type of power source: carbon nanotubes.
UC’s College of Engineering and Applied Science has a five-year agreement with the Air Force Research Laboratory to develop various solutions to improve military technology. Included are smart materials that can power electronics.
Spinning and Weaving
A team led by UC professors Vesselin Shanov and Mark Schulz has created carbon nanotubes that can be stretched over an industrial spool to be spun together into a thread that resembles spider’s silk—one of the strongest known natural materials. It can then be woven into textiles.
Those textiles can leverage properties of the carbon—such as a large surface area that is strong, conductive, and heat-resistant—to generate electricity to power electronics. In doing so, they can eliminate the need for personnel to carry often heavy batteries with them, researchers said in a UC publication.
“It’s exactly like a textile,” Shanov said in UC’s report. “We can assemble them like a machine thread and use them in applications ranging from sensors to track heavy metals in water or energy storage devices, including super capacitors and batteries.”
University of Cincinnati (UC) graduate student Mark Haase stretches carbon nanotube fiber grown in the university’s Nanoworld Lab. Like spider silk, it's stretchy and strong. Researchers are using the material to develop clothing for the military that can be used as a power source. (Image source: UC)Lightweight
Soldiers often carry equipment, such as lights, night-vision, and communications gear, which requires batteries comprising about 1/3 of the weight they carry. If some of that weight is removed by wearing energy-harvesting clothing, it’s a boon for the military, researchers said.
Indeed, scientists are eying carbon to replace existing materials in numerous applications. But researchers must first explore how to leverage the material’s properties optimally, Shanov said. “The major challenge is translating these beautiful properties to take advantage of their strength, conductivity, and heat resistance,” he said.
Many Uses
Some of the new applications for carbon include replacing copper wire in cars and planes to reduce weight and improve fuel efficiency. Carbon also can be used to filter water, as well as provide diagnostic and other medical data through the development of new biometric sensors. Researchers also are eying carbon to replace polyester and other synthetic fibers—a notion integral to the UC team’s work to develop carbon-based energy-harvesting clothing that can recharge devices.
So far, what researchers have accomplished is a bit on the cost-prohibitive side to translate into mainstream textiles for consumer use. But one day, it could be a commercial technology, said Mark Haase, a graduate student who also is working on the project.
“We’re working with clients who care more about performance than cost,” Haase said in US’s publication. “But once we perfect synthesis, scale goes up considerably and costs should drop accordingly. Then we’ll see carbon nanotubes spread to many, many more applications,” he said. Currently, UC’s lab can produce about 50 yards of carbon nanotube thread at a time for its research, whereas large-scale textile machines need miles of thread.
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Filaments Harvest, Store Solar Energy to Turn Clothes into Solar Batteries
Elizabeth Montalbano is a freelance writer who has written about technology and culture for 20 years. She has lived and worked as a professional journalist in Phoenix, San Francisco, and New York City. In her free time, she enjoys surfing, traveling, music, yoga, and cooking. She currently resides in a village on the southwest coast of Portugal.
SAVE THE DATE FOR PACIFIC DESIGN & MANUFACTURING 2019!
Pacific Design & Manufacturing, North America’s premier conference that connects you with thousands of professionals across the advanced design & manufacturing spectrum, will be back at the Anaheim Convention Center February 5-7, 2019! Don’t miss your chance to connect and share your expertise with industry peers during this can't-miss event. Click here to pre-register for the event today!
How to Make a "Hungry" Robot
If you're old enough to remember Radio Shack (and shame on you if you're not!), you probably remember those old coin-eating robot piggybanks. You'd put a coin in its hand and it would “eat” it.
Sometimes, the best robots are less functional and more emotional. Asked why he made this project, creator Eunchan Park simply stated, “This is fun, makes me smile, and feels good.”
Here's how to build your own Hungry Robot using Arduino along with some open-source code and freely available 3D printing model files:
Parts List
Qty
Part
1
1
Adafruit infrared distance sensor
1
PiMill MG90S Metal Gear Micro Servo
2
1
Pack of self-locking white nylon cable zip ties
3
Dupont female-to-female breadboard jumper wire ribbon cables
4
uxcell Hexagon Socket Cap Head Self Tapping Screws Fasteners M 2x8mm
BUILD INSTRUCTIONS
Arduino Setup:
First, we'll need to upload the source code to the Arduino board.
1.) Install Arduino IDE.
2.) Download the source code.
3.) Connect your Arduino to your PC via USB.
4.) Select the board, processor, and com port – Arduino Nano and ATmega328P (Old Bootloader).
5.) Find and select the emerging com port and click “Upload.”
3D Printing Parts:
1.) Download the 3D modeling files from Thingiverse.*
*For each part, the brim setting needs to be at least 1mm.
Circuit Assembly:
1.) All parts are connected using a female-to-female Dupont cable. You'll need to cut and re-wire the cable manually to save space inside the robot. To do this, strip the cables and then twist the wires together and tape them.
2.) The servo motor uses three pins. Vcc and GND is essential and a PWM pin must also be allocated with the servo motor. In this project, pin 12 is used.
3.) The infrared sensor also uses three wires. The Arduino requires an analog input to detect objects at a distance. In this project, A7 pin is allocated.
Hardware Assembly:
1.) To assemble the arms, use a screwdriver to connect the black horn from the servo motor to the the hand (printed with the hand.stl file).
2.) Next, attach the guide piece (guide.stl) behind the servo motor and place the servo motor inside the body (body.stl). Use a screwdriver to fix it in place.
3.) Place the infrared sensor into the body so that it is facing out of the long slot. Then, insert in the inner body “basket” (inner_body.stl).
4.) Affix the hand to the body by threading one cable tie from the inside out, then using another cable tie to hold everything in place.
5.) Attach the head (head.stl) to the body using the same cable tie method. Lock the head in place to the body at the joint and thread a cable tie through.
6.) Now, connect the head and body using the link (link.stl). This is the most important part of the robot's body. Again, you'll want to use the cable tie method.
7.) Connect all of the wires to the Arduino board. Check the color, location, and pin numbers. The diagram below provides a helpful guide:
8.) Place the Arduino inside of the body and plug a USB cable into the Arduino through the hole at the bottom of the body.
9.) Once the Arduino and USB cable are in place, the bottom (bottom.stl) should snap right in place.
10.) Glue the toy eyeballs to the robot and paint/decorate it however you want. Your Hungry Robot is ready to eat whatever you put in its hands!
[All images courtesy Eunchan Park]
Norway Is Opening for Business in Carbon Capture
The Norwegian Ministry of Petroleum and Energy has announced that it will be moving forward with an undersea project for carbon capture and storage (CSS), the first in the world to be able to store carbon dioxide (CO2) waste from multiple industrial sources. If the project is successful, it will serve as a stepping stone for full scale international operations.
The impetus behind this is to get ahead of the carbon capture curve and create an economically viable value chain solution for CCS. When this infrastructure is put into place, Norway will be able to import CO2 for permanent storage, providing a ready mechanism for countries and companies to set up their own CCS operations. It will also lower the threshold for a European hydrogen market. Norway could be getting into the business of importing and sequestering CO2 as a service.
This schematic shows terrestrial and geological sequestration of carbon dioxide emissions from a coal-fired plant.(Image source: LeJean Hardin and Jamie Paynederivative work: Jarl Arntzen [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons)
The country is already the world leader in carbon storage, going back to the Sleipner Project, which has stored one million tons of CO2 per year since it began about 20 years ago. It was the first facility dedicated to CO2 storage and was installed as a means of avoiding the Norwegian carbon tax and reducing the CO2 content of natural gas produced in the area, which exceeded the specified European Union limit in CO2 concentration of 2.5%.
The CO2 was removed using an amine-based sorbent, with the excess being pumped under the seabed to a depth of roughly 1 km. Of the 17 large-scale CCS facilities operating worldwide today, only four are dedicated to carbon storage. Two are in Norway (Sleipner and Snøhvit), one in Canada (Quest), and one in the US (Decatur). The rest are being used for enhanced oil recovery.
The importance of CCS technology is hard to overstate, at least for as long as fossil fuels are part of the energy and industrial landscape. The International Energy Agency (IEA) has called CCS a key technology for reducing coal and gas emissions across industries. In a statement to Business Insider, an IEA spokesperson said, “There is no other technology solution [today] that can significantly reduce emissions from the coal and gas power generation capacity that will remain a feature of the electricity mix for the foreseeable future. No other technology solution is capable of delivering the deep emissions reductions needed across key industrial processes, such as steel, cement, and chemicals manufacturing, all of which will remain vital building blocks of modern society.”
RELATED ARTICLES:This latest demonstration scale project, which is expected to be online by 2020, is unique in that it will capture emission from two different industry types: a cement factory in Brevik, owned by Heidelberg Cement, and an energy recovery (waste incineration) plant in Oslo. These sites all delivered their concept studies for CO2 capture in the fall of 2017. Each plant plans to capture roughly 400,000 tons annually.
In operation, CO2 will be transported by ship from each capture plant to an onshore facility on the Norwegian West Coast for temporary storage. It will then be transported via a pipeline to a subsea formation in the North Sea for long-term storage. The Norwegian Ministry of Petroleum and Energy has identified several injection wells east of the Troll field on the Norwegian Continental Shelf. The CO2 will be stored permanently up to 2,000 meters below the seabed.
According to Equinor, an oil and gas company that is a partner in the project and was involved in the earlier Norwegian CCS projects, “The reservoir surveyed for CO2 storage has the capacity to accommodate significant additional volumes.”
The company will be responsible for the planning of the storage facility and is also looking into the feasibility of pairing this carbon capture capability with hydrogen production. When hydrogen is produced from natural gas, it emits CO2 as a byproduct. But if the CO2 could be safely sequestered, it could provide a carbon-free alternative. Equinor, along with partners Vattenfall and Gasunie, is currently assessing the possibility of converting a natural gas power plant to run on hydrogen and sequestering the resulting CO2 emissions beneath the seabed.
Today's Insights. Tomorrow's TechnologiesESC returns to Minneapolis, Oct. 31-Nov. 1, 2018, with a fresh, in-depth, two-day educational program designed specifically for the needs of today's embedded systems professionals. With four comprehensive tracks, new technical tutorials, and a host of top engineering talent on stage, you'll get the specialized training you need to create competitive embedded products. Get hands-on in the classroom and speak directly to the engineers and developers who can help you work faster, cheaper, and smarter. Click here to submit your registration inquiry today.
RP Siegel, PE, has a master's degree in mechanical engineering and worked for 20 years in R&D at Xerox Corp. An inventor with 50 patents, and now a full-time writer, RP finds his primary interest at the intersection of technology and society. His work has appeared in multiple consumer and industry outlets, and he also co-authored the eco-thriller Vapor Trails.
Filling in Gaps Improves Lithium Ion Batteries
One of the limiting factors in the performance of lithium ion batteries in electric vehicles (EVs) is thermal management of the battery system. Batteries produce heat energy when they are charged or discharged. That energy must be removed, typically through conduction to a liquid cooled heat sink system. Excess heat can reduce a battery’s performance and limit its life. This is especially true as EVs increasingly turn toward fast charging.
At the interface between the battery and the cooling system, gaps and microscopic roughness exist, preventing efficient transfer of the heat energy. A better thermal connection between the battery cells or modules and the cooling heat sink is accomplished using a thermal interface material (TIM) that bridges the gaps and improves conductive heat transfer.
Liquid and Solid
There are two types of TIM products in use: a cure-in-place liquid or a pre-cured thermal pad (sometimes called a gap pad). The liquid gap filler is applied as a two-part system that is applied to one of the two surfaces. The battery and heat sink are then pressed together to reach a specific thickness. As the liquid cures, if forms a solid that fills in all of the gaps and surface micro-roughness. A gap pad is a precut solid material that is compliant enough to fill gaps and surface roughness as it is compressed between the battery and heatsink surfaces.
"Most automotive companies are used to mechanical solutions and this liquid ‘stuff’ is a clear deviation from the norm for them," said Jim Greig, global business manager, electronic materials, at LORD Corporation. (Image source: LORD Corp.)Lord Corporation was one of the first companies to develop thermal gels for the semiconductor industry. Now, it is applying that expertise in developing liquid TIM products for the EV battery industry. “When the need for improved thermal performance of battery packs arose from the EV push, we were able to leverage our technology to develop the CoolTherm thermal management materials we offer today,” Jim Greig, global business manager, electronic materials at LORD Corp., told Design News.
Filling Roughness
Liquid gap fillers flow into the gaps created by surface roughness and can be expected to provide coverage of the interface. “The performance benefits of (liquid) gap fillers versus the more traditional gap pad solutions are clear with better performance at a lower cost,” said Greig. “Our materials are different, which is what sets LORD apart in this space. Most automotive companies are used to mechanical solutions and this liquid ‘stuff’ is a clear deviation from the norm for them,” he told us. The company has written a white paper detailing the benefits of its liquid gap filler technology.
With the wide range of battery designs that are in use in EVs, the liquid gap filler also provides some flexibility and design freedom when designing the thermal management of a pack. “The type and functionality of the thermal management material really depends on the performance needs and the OEM design,” said Greig. “For example, a pouch battery has different characteristics from prismatic or cylindrical cells, and a module or pack application may also have different performance needs.”
RELATED ARTICLES:Manufacturing
Another advantage that LORD claims for its liquid system is in the manufacturing of the battery pack. Thermal pads must be cut to shape, resulting in scrap material and a need of accurate placement. Liquids can be applied more easily, particularly with automated equipment. And they result in little or no waste. The company notes that rework is one of the only areas where liquid gap fillers don’t have an advantage—pads are easier to remove because they don’t conform to microscopic gaps as well, according to information in the LORD white paper.
LORD Corp. is a corporate sponsor of The Battery Show that takes place in Novi, Michigan on September 11-13. “LORD has been attending the Novi show since it started. We have had some great experiences and identified many new opportunities for our solutions,” noted Greig. “These events are really critical for the industry to come together to share new innovations and trends so the industry continues to transform the face of transportation,” he added. A presentation titled "Comparison of Gap Pads & Gap Fillers for Thermal Management of EVs" by LORD Corp. Principal Scientist Tim Fornes will take place at The Battery Show on Thursday, September 13.
Senior Editor Kevin Clemens has been writing about energy, automotive, and transportation topics for more than 30 years. He has masters degrees in Materials Engineering and Environmental Education and a doctorate degree in Mechanical Engineering, specializing in aerodynamics. He has set several world land speed records on electric motorcycles that he built in his workshop.
North America's Premier Battery Conference.
The Battery Show, Sept. 11-13, 2018, in Novi, MI, will feature a talk from Tim Fornes of LORD Corporation along with more than 100 other technical discussions covering topics ranging from new battery technologies to thermal management. Register for the event, hosted by Design News’ parent company UBM.
High Metal Prices Could Disrupt Automakers’ EV Plans
If raw material prices continue to rise, automakers may have to change their long-term battery strategies for electric cars, an expert will tell attendees at the upcoming Battery Show.
Asad Farid of Berenberg Bank contends that recent price hikes in lithium, nickel, and cobalt could keep automakers from hitting their battery cost goals in the next five years, despite huge economies of scale. “Right now, the industry doesn’t have a complete realization of what metal prices will do to battery costs,” Farid, an associate director of the 428-year-old German bank, told Design News. “They’re just starting to understand the risks.”
Asad Farid of Berenberg Bank says that the high cost of lithium, nickel, and cobalt could force automakers to disrupt their long-term battery strategies. (Image source: Berenberg Bank )
In a session titled, Can the Commodity Price Bubble Disrupt the Ongoing Lithium-Ion Battery Cost Reduction?, Farid will tell attendees that automakers may need to set their sights lower in terms of battery size. Instead of employing big 60-kWh and 80-kWh batteries, future BEVs may need to use 30-kWh batteries that offer 120 to 130 miles of range. In some cases, they may also need to augment those smaller batteries with internal combustion engines to extend driving range.
Farid specializes in the study of disruptive technologies and batteries in particular. His analysis shows that a continuing increase in raw material prices would neutralize a 4X increase in manufacturing scale over the next five years, he told us, leaving EV battery pack costs roughly where they are today. Last year, he said, the price of cobalt rose 130%, lithium climbed by 50%, and nickel was up 28%. Even if material prices stop rising and stay where they are, however, he still doesn’t expect battery costs to dip below $150/kWh.
That would create a problem for automakers, Farid said. By his estimate, the economic break-even point that enables an electric powertrain to compete with a gasoline-burning drivetrain is approximately $100/kWh for smaller batteries (30 kWh, 120 miles of driving range) and $60/kWh for larger batteries (60 kWh, 220 miles of driving range).
“Although a battery cost of $150/kWh is a big improvement from where we are now, we would still be quite far away from the break-even point,” he said. The result, Farid believes, is a potential slowdown in the adoption of pure electric vehicles—especially if government subsidies disappear. “In a scenario where battery pack costs bottom out at $150/kWh and no subsidies are available, the automotive OEM would only make money with a smaller battery pack in their electric car,” he added.
That’s a scenario that’s only beginning to dawn on automakers. Up to now, battery pack costs have declined steadily for more than a decade, going from more than $1,000/kWh in 2008 to about $210/kWh today. As a result, many automakers and suppliers have faith that the reductions will continue unabated, enabling the costs to drop below the $100/kWh mark. But that may not be the case, Farid said. “The general expectation is that battery costs will follow a pattern similar to that of solar cells and semiconductors—with increasing productivity, the costs will keep going down,” he told us. “Unfortunately, lithium-ion batteries are a lot more complex than that. They use a lot of expensive materials.”
Farid argues that the commodity price hike in material costs over the past two years is already impacting battery costs. Cathode costs have bottomed out, he said, because lithium-ion cathodes use lithium, nickel, and cobalt.
RELATED ARTICLES:Automakers are watching the raw material costs carefully, but some are still relying on a cost model that may not apply. Larger scale, he said, may drive down the cost of battery management and cooling systems, but it won’t necessarily work for electrodes and electrolytes. “They talk about Moore’s Law in this sector, where an increase in scale will bring your costs down,” he said. “That’s been the mainstream thinking. But there is no Moore’s Law for batteries.”
Automakers like Volkswagen, GM, and Ford, who have announced forthcoming BEVs, still have time to make changes. “They may have to adjust their long-term strategies,” Farid said. “Those strategies are not set in stone.”
Senior technical editor Chuck Murray has been writing about technology for 34 years. He joined Design News in 1987, and has covered electronics, automation, fluid power, and auto.
North America's Premier Battery Conference.Join our in-depth conference program with over 100 technical discussions covering topics from new battery technologies and chemistries to BMS and thermal management.
The Battery Show. Sept. 11-13, 2018, in Novi, MI. Register for the event, hosted by Design News’ parent company UBM.
Looking for Battery Progress in Unlikely Places
Battery researchers at Cambridge University in England have been working on a novel new material—niobium tungsten oxide—to use as a battery electrode. Their initial work indicates that the material may dramatically improve charging times and could find use in future electric vehicles (EVs).
Practical, commercial lithium ion batteries have been available for almost 30 years. They have become nearly ubiquitous, finding applications in everything from personal electronics and medical devices to electric vehicles and utility scale, electrical power grid storage systems. Much of the development of lithium ion batteries has centered on cost and has resulted in a reduction from roughly $1,000/kilowatt-hour (kWh) from a decade ago to today’s price of less than $150/kWh.
Barriers to Fast Charging
If lithium ion batteries are to continue to power our future, however, there are going to have to be some changes. Lithium ion batteries have some of the highest energy densities and power outputs of any electrical storage device. But they pale in comparison to the energy contained in an equivalent weight of a liquid fossil fuel, such as gasoline. Lithium ion batteries are also quite sensitive when it comes to rapid charging, which can cause the formation of spiky dendrite crystals of lithium that form on the anode and can cause fires. Rapid discharging can cause excessive heat buildup within the cells, which can also create a safety hazard.
For much present-day materials research focused on lithium ion batteries, the goal is to develop batteries that can safely charge much more quickly and that contain higher amounts of energy. A battery with such capabilities would be a boon to electric vehicles, which could then travel further on a single charge and recharge in a matter of minutes instead of hours.
Niobium tungsten oxides are under examination by Cambridge University researchers for use as lithium ion battery electrode material. (Image source: Camnbridge University)Battery Basics
Batteries are made of three parts: a positive electrode called the cathode, a negative electrode called the anode, and an electrolyte that allows the motion of ions between the two electrodes. When a battery is charged, lithium ions are extracted from the positive electrode. They move through the crystal structure of the cathode and into the electrolyte, eventually reaching the negative anode, where they are stored. The faster this process occurs, the faster the battery can be charged.
One way to make charging faster is to try to make the particle-size of the cathode material smaller. “The idea is that if you make the distance the lithium ions have to travel shorter, it should give you higher rate performance,” said Kent Griffith, a postdoctoral researcher at Cambridge University’s Department of Chemistry, in a university press release. “But it’s difficult to make a practical battery with nanoparticles: you get a lot more unwanted chemical reactions with the electrolyte, so the battery doesn’t last as long, plus it’s expensive to make,” added Griffith.
No Nano
Many research teams around the globe are researching nano-materials for battery electrodes, but it’s not an approach that the team at Cambridge is necessarily following. “Nanoparticles can be tricky to make, which is why we’re searching for materials that inherently have the properties we’re looking for even when they are used as comparatively large micron-sized particles. This means that you don’t have to go through a complicated process to make them, which keeps costs low,” Professor Clare Grey, also from the Cambridge Department of Chemistry, said in the release. “Nanoparticles are also challenging to work with on a practical level, as they tend to be quite ‘fluffy.’ So it’s difficult to pack them tightly together, which is key for a battery’s volumetric energy density.”
Cambridge is looking at niobium tungsten oxides that have a rigid, open structure that does not trap the inserted lithium. These oxides have larger particle sizes than many other electrode materials. Because of their complex atomic arrangements, such materials have not received much attention for battery applications. “Many battery materials are based on the same two or three crystal structures, but these niobium tungsten oxides are fundamentally different,” said Griffith. “The oxides are held open by ‘pillars’ of oxygen, which enables lithium ions to move through them in three dimensions.”
Griffith went on to say, “The oxygen pillars, or shear planes, make these materials more rigid than other battery compounds. So that, plus their open structures, means that more lithium ions can move through them, and far more quickly.”
Niobium is a soft, ductile transition metal that is not found free in nature, but is combined with other elements in minerals. It is used in steel and super alloy production. Tungsten is also found as a combination of other elements in minerals and has the highest melting point of all elements. It is extremely dense (about 1.7 times higher than lead). Tungsten is considered a rare metal and is used when combined in a carbide as a grinding material, in high temperature alloys, and in munitions, where its high density imparts extremely high impact energy.
RELATED ARTICLES:It’s the Process
Although the Cambridge University work has been published in Nature, the team has not yet made any test batteries with the niobium tungsten oxides. The research has used a technique called pulsed field gradient (PFG) nuclear magnetic resonance (NMR) spectroscopy to measure the movement of lithium ions through the oxides. They found that the lithium moved at rates several orders of magnitude higher than it did in typical battery electrode materials.
The density and rarity of tungsten might not make it the first choice for low-cost battery applications, but it is important to study a variety of materials in order to understand the underlying mechanisms at play. Professor Grey said that it is important to keep looking for new chemistries and new materials. “Fields stagnate if you don’t keep looking for new compounds,” she said. “These interesting materials give us a good insight into how we might design higher rate electrode materials.”
Senior Editor Kevin Clemens has been writing about energy, automotive, and transportation topics for more than 30 years. He has masters degrees in Materials Engineering and Environmental Education and a doctorate degree in Mechanical Engineering, specializing in aerodynamics. He has set several world land speed records on electric motorcycles that he built in his workshop.
North America's Premier Battery Conference.
Join our in-depth conference program with over 100 technical discussions covering topics from new battery technologies and chemistries to BMS and thermal management.
The Battery Show. Sept. 11-13, 2018, in Novi, MI. Register for the event, hosted by Design News’ parent company UBM.
New Thinking Informs Soft-Material 3D Printing
As 3D printing evolves, researchers have gone beyond mere fabrication processes to developing techniques for optimizing how particular materials can be printed. To that end, researchers at Carnegie Mellon University’s College of Engineering have developed a new approach to optimizing the 3D printing of soft materials. This approach combines expert judgment with an algorithm designed to search parameter combinations relevant for 3D printing, they said.
Images of 3D prints made using a new method developed by researchers at Carnegie Mellon. Their approach combines expertise with an algorithm and applies that to a 3D-printing process to optimize the printing of soft materials. (Image source: Sara Abdollahi, Alexander Davis, John H. Miller, Adam W. Feinberg, Carnegie Mellon)Calling their method Expert-Guided Optimization (EGO), the technique—designed by a cross-disciplinary team of biomedical, materials, and social scientists—enables optimal printing for high-quality soft materials with a completely new approach, said Sara Abdollahi, a Ph.D. student in biomedical engineering at Carnegie Mellon.
“We developed the EGO strategy after realizing the lack of systematization in 3D printing, especially involving new materials and processes on which little prior information is known,” she told Design News. “We were seeking an approach that would be easy to implement and flexible enough to modify as needed.”
Algorithm Used for Predictions
Studies have shown that experts are good at selecting factors that matter in prediction, but not so good at combining those factors to make an actual prediction, Abdollahi explained. The team used this idea, but applied it in an engineering context to develop a product. “Specifically, the expert was used to inform and start off the search, which was followed through with an algorithmic search to combine the expert selected parameters to make a prediction for the optimum [result],” she explained.
In essence, what the team achieved for the first time was to use a concept from the social and decision sciences to inform an engineering problem, Abdollahi said. “From a practical standpoint, we were able to systematically optimize 3D printing of soft materials without the need for complex physical models, a data training set, or haphazard trials,” she said.
The team published a paper on its work in the journal PLOS One. It demonstrated the EGO method by printing objects made of liquid polydimethylsiloxane (PDMS) elastomer resin, which is often used in wearable sensors and medical devices, with a freeform reversible embedding (FRE) printing method.
Researchers Printed “Calibration Objects”
Abdollahi said the concept can be applied for other 3D-printing processes, such as binder jetting, vat polymerization, and others, as long as the parameter space for each of those processes can be defined.
“Broadly speaking, the method explores random combinations at first, giving an opportunity to gauge different sets of factor-levels selected by the expert,” she explained. “Once a promising combination is found (i.e., a parameter set that produces the fittest print), the approach is to work around this combination iteratively toward improvements.”
Specifically, researchers printed what are called “calibration objects” in 3D printing—that is, a cube and a cylinder, Abdollahi told us. “This is fitting in the context of soft-material 3D printing, using the FRE technique, than is a more recent 3D printing approach on which an extensive library of geometries and sizes is lacking,” she explained. “To get an idea of the sort of prints that can be developed with this tool, a good starting point would be to look at what is possible to create with the technology at hand.”
Standardizing the Approach
Researchers plan to continue their work to explore using other materials, more complex geometries, other search algorithms, and other 3D printing processes or even a different process altogether, Abdollahi said. “A farther vision would be in determining the steps to standardize this approach and see it being applied in industry and real-world context,” she added. “This model has the potential to save time and effort, but also money if we think about the costs that go into the iterative design of products in manufacturing and prevent unnecessary waste products, which can be significant, for example, in 3D printing of metal parts.”
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Elizabeth Montalbano is a freelance writer who has written about technology and culture for 20 years. She has lived and worked as a professional journalist in Phoenix, San Francisco, and New York City. In her free time, she enjoys surfing, traveling, music, yoga, and cooking. She currently resides in a village on the southwest coast of Portugal.
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Modifying Electrolytes to Improve Lithium Ion Batteries
Lithium ion batteries are here to stay. Yet there are aspects of these electrochemical storage devices that can be improved. One such area is the electrolyte. Neville Pavri, research chemist at Halocarbon Products Corp., will give a talk at The Battery Show in Novi, MI on September 12 titled, “Fluorinated Materials to Help Improve Performance in Lithium-ion Batteries.” Pavri has worked on fluorinated electrolytes for several years and spoke with Design News about some of the advantages of this new concept.
Organic Issues
The liquid electrolyte inside a commercial lithium ion battery is an organic solvent. Its job is to allow the passage of lithium ions between the positive (cathode) and negative (anode) electrodes during charging and discharging. It also must prevent self-discharge that would occur if electrons could pass through the electrolyte between the anode and cathode. As long as voltages remain below 4.2 volts, the organic solvent electrolytes are stable. To increase energy density and storage capacity, researchers would like to increase the cell operating voltage to 4.4 volts or higher. But there is a problem.
Normal organic solvent electrolytes begin to oxidize when the voltages reach the 4.3 to 4.4 volt range. “The main goal with lithium ion batteries in the near future is two-fold. You want to make the battery safer and you want to enable higher energy density,” Neville Pavri told Design News. “The currently used materials that are used for electrolytes in the batteries today tend to not be stable as you go to higher voltages. As you go to 4.3 or 4.4 volts, the materials that are used to make the electrolyte today start breaking down because they do not have good oxidative stability,” he explained.
Despite having an energy density among the highest of all electrochemical batteries, lithium ion cells are still far behind liquid hydrocarbon fuels, such as gasoline. Increasing energy density would improve laptop or cellphone life or distance traveled by an EV on a charge.
Fluorinated electrolytes have been demonstrated to help drive new levels of safety and performance in high-voltage cells. (Image source: Halocarbon)
Fluorine
Pavri heads a research effort at Halocarbon to examine fluorinated materials as additives or co-solvents for the organic electrolytes. “Using fluorinated solvents, that we prepare, they tend to be much more oxidatively stable,” said Pavri. “You need a lot more energy to break a carbon fluorine bond compared to a carbon hydrogen bond. Since you need a lot more energy, the compounds are more stable and they can be used at these higher voltages without as many issues,” he told us. “Fluorinated co-solvents and additives have much greater oxidative stability. They will tend not to decompose as you go to 4.3, 4.4, 4.5 volts.”
Halocarbon is particularly well-placed to do this type of research. “We have a lot of experience making different fluorinated molecules,” said Pavri. “About two years ago, we were looking for new markets to enter and figured that we could enter into the lithium ion battery market. We have the ability to put fluorine on different parts of molecules and then study how they will behave inside the system, which in this case is a battery system. We quickly realized that our specialty is making organic compounds, so we went ahead and partnered with electrolyte manufacturers and battery companies and started to test our materials in the batteries with their help,” he explained.
Structured Approach
“We are using this structured activity relationship (SAR) approach to narrow down the candidates that have the best efficacy, not only in cycling, but also in reducing the flammability of the electrolyte and other additive properties, such as anti-gassing and making better SEI (solid−electrolyte interphase ) layers,” said Pavri. In most photographs of spectacular battery fires, it is this electrolyte that provides the fuel. “When you replace hydrogen with fluorine in a compound, you usually reduce the flammability,” noted Pavri.
RELATED ARTICLES:Thanks to Halocarbon’s open innovation approach to the lithium ion electrolyte additives that it is developing, the company is finding real power in working together with its industry partners. “We are not coming into this market with just one compound. Halocarbon is a specialty fluorocarbon company, and we already make a wide variety of fluorinated compounds,” said Pavri. “Many of them are made in up to hundreds if not thousands of metric ton scale. Other products that Halocarbon makes are specialty oils, greases and waxes, pharma compounds, and fluorinated anesthetics.” This gives Halocarbon the flexibility to produce a range of different fluorocarbons at additive quantities.
The ability to make large quantities of potential additives also means that some new battery chemistries could be available in as short as six months, although the expected time frame for adoption by automotive customers is probably more like 2-3 years, according to Pavri.
Senior Editor Kevin Clemens has been writing about energy, automotive, and transportation topics for more than 30 years. He has masters degrees in Materials Engineering and Environmental Education and a doctorate degree in Mechanical Engineering, specializing in aerodynamics. He has set several world land speed records on electric motorcycles that he built in his workshop.
North America's Premier Battery Conference.
The Battery Show, Sept. 11-13, 2018, in Novi, MI, will feature a talk from Neville Pavri, along with more than 100 other technical discussions covering topics ranging from new battery technologies to thermal management. Register for the event, hosted by Design News’ parent company UBM.
Understanding Hybrid Dual-Curing Adhesives
In a vast number of industries, including automotive, electronics, and mechanical engineering, bonding has become more important due to light-weight construction, miniaturization, and multi-material design. Adhesives are also increasingly being used as sealants to protect components from environmental influences.
For productivity reasons, most manufacturing companies—as well as those producing mass goods—prefer light-curing adhesives to achieve high productivity levels. A light-curing adhesive helps to provide high positioning accuracy, as components can be initially fixed on demand. Once applied, the adhesive does not flow, which can happen when using heat-cured products in the oven.
However, these systems are subject to limitations. Light-cured adhesives achieve full strength within a couple of seconds when irradiated (in specials cases, even less than a second). This is achieved with high-energy LED lamps that generate 100 to 1000 times the intensity of normal daylight within their specific light spectrum. The materials used in these systems are subject to limitations, given maximum implementation temperatures of more than 150°C and regular contact with aggressive chemicals, oil, and acid.
In recent years, adhesive manufacturers have focused on pushing these limits further by developing several dual-curing products. Dual-curing adhesives offer the benefits of light-curing systems without compromising on reliability, bond strength, and processing quality. They ensure that the adhesive in the finished product is fully cured and also permit maximum bonding precision in complex modules. In addition, they offer a high degree of flexibility in production while allowing users more freedom in the development of their production processes.
Light-curing adhesives are a great choice for mass goods, but shadowed areas that cannot be reached by light present a challenge for them. (Image source: DELO)
Where There Is Light, There Is Also Shadow
When two components are bonded, it is important that all of the adhesive is fully cured. If the light only reaches some of the adhesive, it will remain liquid in the shadowed areas. This exposes components to the risk of corrosion or, in the case of optical products, an undesirable effect on the light path. Shadowed areas should be avoided from the start of the design stage if light-cured adhesives are used.
RELATED ARTICLES:The adhesives industry has developed many new dual-curing products for situations in which it is not possible or very difficult to avoid shadowed areas. Aside from light, a second curing mechanism—either humidity, air exclusion, or heat—is used so that adhesives can bond reliably, even in shadowed areas. There are three main options, each of which fulfills different requirements and permits various manufacturing processes. All are one-component products that are isocyanate- and silicone-free, with the exception of UV silicones.
Using Natural Humidity in the Air
After initial fixation, light-/humidity-curing adhesives react with the natural humidity in the air in the shadowed areas. One benefit is that no additional equipment is necessary and no other curing process step is required after light curing. Bonded components can be further processed immediately.
Light-/humidity-curing adhesives are based on acrylates. In shadowed areas, they polymerize with humidity. (Image source: DELO)
In chemical terms, light-/humidity-curing adhesives are closely related to conventional light-curing acrylates and possess similar properties. Due to the simplicity of the process, this product group is selected for medium requirements—at maximum temperatures of use of 120-150°C and moderate chemical impact. UV silicones work on the same principle and can even be used in temperatures of up to about 300°C. However, due to their low strength, they are only suitable as sealants and also possess the typical disadvantages of silicones, such as swelling and contamination of production plants.
Light-Anaerobic-Curing Adhesives
If requirements are higher, anaerobic curing is used as the second mechanism instead of humidity. Light-/anaerobic-curing adhesives offer high strength levels and temperature ranges up to 180°C. They can be used for challenging applications in electric motors with high heat dissipation levels. They are also resistant to chemicals like brake fluid, oil, and road salt that are encountered in the automotive sector.
Light-/anaerobic-curing adhesives are often used in mechanical engineering. They cure in shadowed areas viacontact with metal ions and oxygen exclusion. (Image source: DELO)
Light-/anaerobic-curing adhesives are based on widely used metal adhesives. Therefore, they need metal ions and oxygen exclusion to fully cure in shadowed areas. They offer two benefits compared to traditional metal adhesives. Productivity is higher due to fast light fixation. In addition, the adhesive cures on the fillet, where otherwise air is frequently found. Both the purely light- and anaerobic-cured areas are well-cured and share similar properties. If sufficient metal ions are available, these products do not require a further process to cure in shadowed areas.
Full Power: Light Plus Heat
The third option is light-/heat-curing materials, in which heat is applied to achieve full bond strength. This group is the most diverse. It offers products based on epoxy resins, acrylates, and other chemicals, with the latter mainly used in optoelectronics, thanks to its high transparency and low yellowing and outgassing.
Light-/heat-curing adhesives combine the bonding precision of light-curing products with the resilience of heat-curing materials. (Image source: DELO)
Epoxides tend to display higher strengths. They are harder and, because of their denser network, resistant to chemicals and high temperatures. Some of these products are so resilient that they can be used in modules that are permanently in contact with hot transmission oil. Acrylates are softer and therefore more flexible and tension-equalizing, letting them better compensate dynamic stress. An example of this is the attachment of decorative trims and cockpit elements in cars, where component tension needs to be equalized in a temperature range of -40 to -100°C.
These product groups share a common feature in that they fix components with UV or visible light within a few seconds, thus ensuring high production precision compared to standard products. Component shifting on the way to or during heat curing is avoided.
Convection ovens are usually used to supply the necessary heat for final curing. Alternatively, tunnel ovens, induction, or thermodes can be used. Typical temperatures are around 100°C, while the highest reliability products need at least 120°C and temperature-sensitive components can be bonded with other materials at as little as 60°C. As a result, high precision, defined production processes, and short cycle times can be combined with low thermal stress.
Dr. Karl Bitzer is a product manager at DELO Industrial Adhesives.
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