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 and materials must drop, and the reliability of the technology must rise.
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.
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.