Collaboration between industry, universities, and government agencies is making composite manufacturing faster, more efficient, and cost effective. Below is an article published by Composites Manufacturing Magazine announcing the latest innovations in additive manufacturing, automated production, machining, and molding methods.
Imagine going to a car dealership and ordering a new vehicle custom-made to your specifications, but you don’t wait a month or more for delivery. Instead, you pick up the car very next day. Thanks to advances in 3-D printed composites, that scenario is close to reality. Using technology developed by the Manufacturing Systems Research Group at Oak Ridge National Laboratory (ORNL), at least one entrepreneur is preparing to launch a car-printing micro-factory and sales outlet.
3-D printing isn’t the only recent breakthrough in composites manufacturing. Industry, universities, government agencies and others throughout the world are exploring improved methods of composite fabrication. Whether they’re working on additive manufacturing, automated production, more precise machining or new methods of molding, the goal is to make composites manufacturing faster, more efficient and cost-effective.
Bigger and Better
ORNL researchers have been working on additive manufacturing for more than 20 years, but until five years ago the projects were all small-scale. “Almost all 3-D printers are in an oven, since they have to keep parts close to the glass transition temperature for plastics. Even for metal, you have to keep the parts really hot while you’re growing them,” says Lonnie Love, corporate fellow and group leader at the Department of Energy’s Manufacturing Demonstration Facility (MDF) at ORNL. Using ovens limited project size and required a lot of energy.
Then the researchers realized that carbon fiber could solve some of the technology’s fundamental problems. “When you put in carbon fiber, it not only increases the strength and stiffness, it also increases thermal conductivity and decreases the co-efficient of thermal expansion such that you no longer need the oven,” Love says. That eliminated all size constraints.
Using carbon fiber, a gantry system and additive manufacturing, ORNL successfully partnered with Lockheed Martin to print big molds for sheet metal forming and composite tooling. “We could make something in a day for thousands of dollars that typically would take months and cost hundreds of thousands of dollars,” says Love. BAAM (Big Area Additive Manufacturing) became a game-changer.
In 2014, ORNL teamed with Cincinnati Inc., a build-to-order machine tool manufacturer, to adapt its laser cutting machine to additive manufacturing. They partnered with car manufacturer Local Motors and printed a composite car during the International Manufacturing Technology Show in September 2014. Cincinnati Inc. has since sold several of its additive printing systems to manufacturers in various industries, and Local Motors plans to sell 3-D printed cars this year at its microfactory across the street from the Manufacturing Demonstration Facility in Knoxville, Tenn. Factory technology is highly important to a companies success as they need are constant relying on it in order to produce enough of a product to meet demands. Therefore if you think you need an upgrade to your industrial computing or need a unit custom made for your businesses needs, take a look at CKS Global as they offer a range of industrial technology to give your production the support it needs.
Over the last few years, ORNL has 3-D printed everything from a Shelby Cobra and a house and vehicle that wirelessly share energy to molds for plane parts and wind turbine blades. During this time, researchers have steadily reduced the time it takes to print these structures. To keep costs down they use readily-available injection-molding pellets as the printing material. The technology has received critical acclaim in the composites industry, winning the 2015 CAMX Combined Strength Award.
“We can now make large structures extremely fast and extremely inexpensively,” Love says. “You can make molds, jigs and fixtures, but if you want to make an end-use part, you don’t need any tooling; you can just go directly from your CAD design to the part, so everything can be different. One of the big benefits of additive manufacturing is mass customization of a product.”
The degree to which additive manufacturing will replace traditional manufacturing depends largely on two factors, says Love. The cost of the machines (i.e. an aluminum rail jib crane) and materials must reduce in price, and the reliability of the technology must rise to keep up with market demands.
Automated Production
While additive manufacturing offers exciting possibilities, research labs and private-sector companies have been improving traditional manufacturing methods as well. Automation is often at the forefront of these improvements. Car manufacturers use robots to assemble relatively small, consistently-shaped parts. But these robots don’t work with large CFRP parts because the parts lack shape consistency due to hand-laying fabrication and autoclave curing.
Car part manufacturers will often utilize laser marking machines to achieve complete part traceability of everything they produce. Things like data matrix and QR codes, barcodes, or even logos, vehicle identification numbers, and serial numbers all have to be marked onto the parts directly.
The Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM has been looking at ways to overcome these problems. Dirk Niermann, who heads the department of automation and production technology, says researchers, working with Airbus, used precise measuring, computer software and off-the-shelf robots to join large CFRP parts on a fuselage.
Although the geometric difference between the manufactured CFRP fuselage parts is small – under one millimeter, according to Niermann – this difference is too great when you have to drill holes in the fuselage within an accuracy of 0.1 or 0.2 mm. To ensure that the holes go in the right position in each fuselage shell, Niermann’s team measured the size, shape and position of every element in the placement process, from the shell to the robot system itself. They then input the data into a software program. With the image in the computer’s virtual world exactly reflecting reality, researchers could control the robot’s precise placement of brackets, pins and spars for the fuselage’s interior.
There were other challenges when it came to joining two sections. Although CFRP parts are stiff, they are limp when large and very thin. Manufacturers usually force the parts into rigid shaping jigs for joining, but this creates stress in the part. So the Fraunhofer IFAM researchers developed a flexible jig, a shape and positioning robot with vacuum actuators.
Using precise measurement data, the computer determined the geometry of each fuselage shape for the best fit, then directed the vacuum actuators to gently move the parts into position. This minimized stress on the parts, optimized the forces applied for joining, minimized the gap sizes and allowed more precision in the amount of adhesive used.
“We did all of this using robots off the shelf – the robots the automotive industry uses,” Niermann says. The team “taught” the robot, positioning it in 15 different ways and measuring the difference between its actual position and the ideal one. Using this data, a software program created an individual mathematical model to control the robot in a very precise way. The program even allowed for the bends in the linear track caused by the robot’s weight as it moved along the axis.
“There are other, already known ways to ‘use’ such data, but our unique way – via the adaption of the mathematical model that controls the robot – makes the decisive difference between precise enough for our purpose or not usable for our purpose,” Niermann says. “With this method, we make sure the robots ‘know’ their own deviations and act accordingly.”
Using robots and a camera system for the final quality inspection improved the speed and accuracy of manufacturing. “We used half the time, sometimes one-third the time that the human teams needed to perform the same tasks,” Niermann says. “And this automation has high reliability, which is what the industry looks for. We don’t have the variances of human work.”
The jig with actuators and the robot positioning algorithm offer manufacturers more flexible production processes. “This jig can hold every type of part, and the robot can work on every type of part,” Niermann says, noting that this is a much cheaper solution than any used today.
Precision Machining
One of BCT GmbH’s contributions to industry advancements focuses on precision machining for composite repair and manufacturing. BCT uses a six-axis, precision measuring system in applying its adaptive machining and system integration expertise to automation of composite repair.
“Our core challenge was to significantly increase the speed and precision of the scarfing process for composite components in need of repair,” says Jan Bremer, project engineer, composites. “Adaptive machining allows fully-automated machining processes on components which have individual deviations while maintaining high precision.”
For one project on a large helicopter fuselage, BCT scanned the component with a laser line scanner. It then digitized the information and adapted its usual three-axis machining path program into a five-axis program to allow for the component’s curvature. (The five-axis program can be “translated” into programs for all types of numeric control machines, Bremer says.) This process ensured that the machining tool followed the fuselage’s exact shape. “When scarfing, it is extremely important to machine to tight tolerances to avoid unwanted damage to underlying areas or components,” Bremer says.
The biggest advantages of this automated process are its increased speed, precision and traceability, he adds. Using a precise machine tool minimizes human error, while digitizing the before and after scarf allows storage of information for later documentation. The same technology can also be applied to machining of parts to ensure better fit during manufacturing.
“I see major advantages in more efficient and precise machining operations, especially when considering the possibility of running machining operations on smaller and more flexible machines that can even work in parallel on large components,” Bremer says. “This could do away with the need for extremely large machinery in many applications, greatly increasing the efficiency of today’s manufacturing processes.”
Larger-scale Production
Teijin Limited of Japan introduced its Sereebo™ carbon fiber reinforced thermoplastic (CFRTP) about five years ago and since that time has worked with GM and other partners on exploring its potential. What sets Sereebo apart from other CFRTPs, according to Teijin, is the longer length of its carbon fibres. Another process that is something new is the process of a waste removal system actively aiding production, plus protecting staff and the business. If you were to look into this, you’d see from Integrated Air Systems that there are plenty of benefits with this- Instant removal of scrap from the working environment can improve the work space, reduce health and safety and fire risks.
“We are able to control the distribution and the orientation of those fibers very well,” says Eric Haiss, vice president at Teijin Advanced Composites America. “So we get isotropic properties in the base material, and we can maintain those properties in the final molded parts.” With its strength and 60-second takt time (which synchronizes rate of production with rate of demand), Sereebo provides the performance required for mass production of structural parts in automobiles, adds Haiss.
“When you go into a typical thermoset process – a high pressure RTM process – that will top out at around 50,000 units a year. That’s pretty much where our process will start,” he says. “Our target is to go after hundreds of thousands of vehicles a year, maybe even millions of units.” Haiss envisions a system where the Sereebo parts would be molded in a factory located near its customers’ factories, with the material itself supplied from a centralized location.
Parts made with Sereebo are typically 20 to 30 percent lighter than those made with aluminum, but they are priced slightly higher. “There are features in our material – maybe better fatigue properties or better impact properties than aluminum – that will give us an edge in certain applications,” says Haiss.
The material is now in the final stages of production process validation trials, and Sereebo may soon move into actual vehicle applications.
Laboratory Research
The Institute for Advanced Composites Manufacturing Innovation (IACMI-The Composites Institute) is a recently-established U.S. consortium of industry, research and state partners working together to accelerate development and adoption of cutting-edge manufacturing technologies for low-cost, energy-efficient manufacturing of advanced polymer composites. IACMI’s mission is to help composite laboratory processes and materials make the big jump to commercial readiness. Its five research areas include vehicles, wind energy, compressed gas storage, materials and processing, and modeling and simulation. It also is collaborating with ACMA on composites recycling and workforce development.
“Within the materials and processing area, we include fibers and resins,” says Cliff Eberle, IACMI’s area director. “Our emphasis is on low-cost carbon fibers because that’s where we see the greatest need and opportunity for making dramatic changes.”
While the aerospace industry has made advances in carbon fiber manufacturing, its breakthroughs are geared to extreme performance at high cost and low volume. “What we’re trying to do at IACMI is extreme volumes at low cost and high, but not super, performance,” Eberle says.
IACMI currently has three projects underway. In wind energy, researchers are looking for ways to reduce the cost of turbines and be more cost competitive. In the compressed gas storage area, the aim is to lower the cost of onboard storage of less-polluting alternative fuels such as natural gas. Researchers in the automotive area are focusing on three processes – prepreg compression molding, high pressure RTM and hybrid molding, says Eberle.
With hybrid molding, manufacturers can take a simple prepreg, compression molded or HPRTM molded part and add complex features by over-molding in an SMC or injection molding process. “You can actually flow materials to give you the complex features but you’re getting the strength and rigidity from the continuous fiber architecture in a prepreg or RTM,” Eberle says. The five-year goal for all three processes is a three-minute, part-to-part cycle time.
IACMI researchers primarily use the equipment already available through its university and national laboratory partners and is strategically growing its capabilities. “In Detroit we are collocating in a full-scale facility where we will have a 4,000-ton compression press, a 3,000-odd ton injection molding press, a full-scale HPRTM unit and a half-meter prepreg line,” says Eberle. “All of this allows us to prototype full-scale automotive parts in that facility.” This investment is necessary because the consortium’s automotive members can’t interrupt their full-scale production lines to conduct research.
The new automotive composite equipment will be located in the same building as the Lightweight Metals Manufacturing Institute (LIFT), which Eberle says is exciting and makes sense. “We don’t think the car of the future will be a composite car; it will be a multi-material car that will use composites, aluminum, steel and other light metals,” he says.
With the variety of research in composites manufacturing that’s going on today, it’s too early to tell which new technologies or processes will actually succeed in the real world market – or when. But with so many viable options, future developments are sure to open up new and exciting possibilities for using composites.
Advances in manufacturing go hand-in-hand with development of new materials. This is especially evident in the area of multifunctional composite materials, where a quick glance at potential military applications reveals the need for compatible manufacturing processes.
For war-torn areas, autonomous vehicles manufactured with protective multifunctional materials could shield both civilians and soldiers in dangerous environments. Some of the required manufacturing technology already exists. Composite materials currently used for soldiers’ personal protection (Kevlar® and Dyneema® helmets and body armor, for example) could be incorporated into Robotic Augmented Soldier Protection (RASP) to deflect hostile projectiles, such as ballistic fragments or bullets.
Robots with built-in composite fiber nets could catch and defeat autonomous vehicles launched by hostile forces, while those manufactured from “smart” composite materials could travel to wounded soldiers during a battle to provide medical treatment and better protection from ballistics. Self-assembling, lightweight composite autonomous vehicles could reconfigure themselves to build shelters or could carry ultra-light, ultra-strong tows to construct an emergency bridge.
“Other composite processes could enable multifunctional robotic platforms that could build protective barriers on site from indigenous materials such as sand or cement, deploy filters for water purification, or autonomously deploy energy harvesting devices manufactured from composite materials for small or temporary wind farms and solar collectors,” says Shawn Walsh, a researcher with the U.S. Army Research Laboratory at Aberdeen Proving Ground in Maryland.
Before such robots can become a reality, however, there’s more work to be done. “As new robotic enabled capabilities are invented and use composites, they may need new and unique manufacturing processes that don’t currently exist, or that require radical modification,” Walsh says.
Author: Mary Lou Jay, Composites Manufacturing Magazine
Photo Credit: ©Fraunhofer IFAM