Lattice structures representation in 2D drawings: a proposal for a standard

The interest in the Additive Manufacturing (AM) technology is surging due to its capability of printing components with complex optimized shapes that fit industrial engineering necessities better than traditionally manufactured parts. However, conventional Computer Aided Design (CAD) software packages are often limited to deal with such complex parts, especially when the AM part is designed using lattice structures: these are structures composed of repeated small elements, called cells, across a domain which generate a light and stiff component. The scope of this work is to analyze the problem of the lattice bidimensional representation and propose a standard for representation in assembly and 2D drawings. Rules useful to handle such hierarchic structures in CAD tools is developed, and a code in Python for the open-source software FreeCad™ has been developed to evaluate the effectiveness and usability of the standard. Simplified symbols to describe complex lattice structures instead of drawing all the small elements forming the lattice have been developed. The standard is useful in technical drawings for assembly representation where lattice components are used (assembly operators, maintenance, parts catalogues). A case study is included to describe how the proposed standard could be integrated in a 2D drawing following technical product documentation production typical workflow.