In the research project “Development of 3D-printed, highly-integrative clamping templates for CFRP components”, a clamping template with integrated functions was designed as a prototype for finishing workpieces made of carbon fiber-reinforced plastics (CFRP).
CFRP components are manufactured close to the final contour, so that a last machining step is only required to finish the edges of the workpieces or to add functionalities such as holes or cutouts, for example. Due to their mostly open design and large surface area, these parts are very unstable and tend to vibrate despite their high inherent rigidity, which decreases tool life and impairs component quality, e.g. dimensional accuracy and edge quality. To avoid this problem during finishing processes, clamping templates are used to reduce vibrations. These support the entire surface of the CFRP components and are clamped in place by means of a vacuum. The clamping templates are typically milled from a large solid block of plastic or metal, meaning that a great deal of material has to be removed. This is an extremely time-consuming process that involves a lot of equipment, is expensive and wastes valuable resources. In addition, adding functionalities such as milling or suction channels through the clamping template is extremely costly, since this requires complex, multi-sided drilling and milling steps. The massive shaping tools and clamping templates are also extremely heavy and can often only be transported by industrial trucks.
Against this background, the research institutes involved in the project investigated more efficient ways of manufacturing highly-integrative clamping templates by combining additive and subtractive processes, i.e. printing the templates by extrusion 3D printing and subsequently cutting the functional and support surfaces to achieve the final shape, and went on to build a demonstrator clamping template. Extrusion-based 3D printing has several advantages, such as a high output rate and the use of an inexpensive injection molding material, which means that customized end products can be produced both quickly and economically. The layer-by-layer structure of additive manufacturing enables almost unlimited design possibilities, making it easy to integrate functionalities such as vacuum fields and milling and suction channels. Significant weight savings can also be realized through the targeted inclusion of hollow structures, resulting in greater material efficiency, shorter printing times and easier clamping devices handling.
The potential of additively manufactured clamping systems for finishing CFRP components is already clear. Further studies on the general suitability of additively manufactured clamping devices for real CFRP parts, in particular with regard to the specific requirements of large-sized workpieces in the aerospace and wind energy sectors, are the subject of current and future research work.