Although thermoplastics manufacturing is moving toward more automated production, there’s still a need for humans in the production process, Leach says. He expects to see an increase in cobots (collaborative robots) that are small enough and safe enough to work alongside people on the manufacturing floor. The cobots can handle the dangerous, repetitive parts of the job, such as transferring a hot blank to a stamp forming machine. That frees up people to take on jobs that require judgment, like parts inspection.
Thermoplastic materials can be melted and reformed, which allows for parts to be welded together to create larger, more complex components. Welding reduces the need for fasteners, which saves production time, reduces the weight of parts and eliminates the need to put holes in laminates.
“Any composites designer or stress engineer out there will tell you that a primary limiting factor of composites is the fastener,” says Young.
Induction welding of CFRTP is attracting a lot of attention in the industry. The process uses a robot equipped with an induction coil, which creates a magnetic field that interacts with the electrical and magnetic properties of carbon fiber to induce heating. The weld is formed when two carbon fiber laminates are brought into contact and a robot moves the induction coil just above the areas where the heat is needed.
Over the last three years, a project team at Qarbon (formerly Triumph Aerospace Structures) has been working to refine this process. Since the electrical properties of various carbon fiber materials vary, they react differently to the induction welding process. So, the Qarbon team has patented a way to focus weld energy without a susceptor and developed sophisticated methods to design the induction coil for specific materials and processes. (Susceptor material, usually metallic, is sometimes included at the joint of the composite part to induce heating, but potentially lowers joint strength.) Qarbon’s technology will enable OEMs to create a part using the material that best suits their needs; the manufacturer can then create the induction welding coil optimized for that material and that part, according to Young.
There’s no diminution in the composite part strength with welding. During a test program with an aircraft OEM, the Qarbon team demonstrated that the joint strength of an induction weld exceeds that of an equivalent fastener and other joining technologies.
In developing the induction welding technology, the project team has produced both a flat demo box, which resembles a horizontal aircraft tail, and a curved box, which is the shape of many aerospace structures.