Working closely with Electroimpact, WITTENSTEIN engineers worked to update an AFP machine design with the Galaxie^®. The results were profound – increased productivity, reduced stress on machine components, and increased positioning accuracy making it possible to produce large parts like aircraft wing spars and skins in a single piece. These optimized AFP machines now also have cutting-edge contouring abilities, which help aerospace engineers produce more slender and aerodynamically ideal wings. Zero backlash can be realized throughout the drive system’s entire lifetime through selective inner tensioning and the build-up of a hydrodynamic lubrication fi lm during surface contact. On top of this, the compact design permits more flexible motion control for use in the rotary axes.

Only one step is required – as opposed to three in the past – to make the forward and rear wing spars, which are up to 33.5 meters long. A modular AFP head weighing about 500kg is integrated with a mobile gantry structure 6 meters wide for this purpose. It applies several hundred layers of epoxy resin-impregnated carbon fiber strips and sheets to the basic structures with absolute precision. After applying one course within any given ply, the machine head does a 180° turn, positions itself anew and applies the next course in the opposite direction. The AFP machine for the wing spars is able to rotate the robot head through ±90° with incredibly high accelerations so that the U-shaped spar structures can be made in a single operation.

See it in action in this video. 

Like WITTENSTEIN, the drive to innovate is constant at Electroimpact. After developing the aforementioned ultra-dynamic AFP machines, the next opportunity for improvement lay within the modular AFP heads.  Since the beginning of fiber placement at Electroimpact, there has been a pendulum swing between machine performance with head performance. The servo creel is a response to an imbalance of head performance lagging machine performance.  The standard AFP head uses a single servo motor, along with controlled brakes on each spool, to accelerate and control each of 16 tows (on most heads). The servo creel adds a dedicated servo to each spool (replacing the spool brakes) and allows ultimate control of the rotation of each spool.  After trying some “other” gearboxes, Electroimpact settled on the smallest version of WITTENSTEIN’s TP⁺ series gearboxes (16 per head!) that combine superior rigidity, efficiency, torque density, compact packaging and low mass to form the heart of the servo creel system.  The results of the multi-year effort have been staggering.  Dynamic performance of the servo creel AFP heads in is now on par with the machine – allowing the fastest and highest quality layups to date.

"These machines are a quantum step in performance from our past efforts. The cool thing is that we are asking less of the process to get this work done. For both wing skin and spar machines; we are regularly achieving payout speeds up to 4000"/min. On the spar machine, we see over 700 lbs. per hour instantaneous, and on the skin machine a whopping 3,500 lbs. per hour instantaneous."

Todd Rudberg, Director of AFP, Electroimpact

Learn more about the cutting-edge AFP machines from Electroimpact