Additive manufacturing allows more design freedom than traditional manufacturing techniques. New shapes can be created, functions integrated into shapes or different materials combined. Combining several materials into multi-materials is becoming increasingly important for the industry. These gradient materials emerge from additive manufacturing - materials whose properties are continuously shaped along a spatial direction, geometry or load. This can be achieved by modifying the material composition or the process parameters in the manufacturing process. In this way, the material properties within a component can be specifically adjusted, for example a flowing hard-soft material gradient on a damping element. With the GraMMaCAD (Graded Multi-Material CAD) software, the Fraunhofer Institute for Computer Graphics Research IGD provides industry with a tool for their CAD geometries that can be used to interactively define material distributions and material gradients in the development process of virtual products. Until now, the definition of locally varying properties on CAD models has been a time-consuming process. The common practice is to either divide the model into submodels to which different materials are then assigned. However, this usually only allows discrete material transitions. Alternatively, materials are assigned using images (textures). In this case, the grading is generated by varying the texture information.

So how can locally varying material information be generated within a three-dimensional component with little effort? GraMMaCAD generates volumetric material distributions and material gradients interactively and uses a graphically interactive editor. The starting point is a CAD model. Users can choose between three approaches to generate material distributions. With the first approach, they can select surfaces of the CAD model. Auxiliary geometries form the second approach. For example, the user can select one or more newly created planes.

The first two options generate a graded material gradient based on the selected surfaces, whereby the type of material gradient can be influenced graphically and interactively. The third approach results when the user assigns material information to components of the CAD model and activates the interpolation of the material properties between them. In this case, the user must first divide the CAD model into sub-bodies in CAD software and can then either assign a specific material to each sub-body or declare it as graded. GraMMaCAD then generates the material gradient automatically.

Multi-material 3D printers, which can process different materials, are increasingly entering the market and creating functionally graded objects for sophisticated designs.

According to documents from Fraunhofer IDG / am