4.9 Fundamentals of additive manufacturing
Unlike casting, forming or powder processing, additive manufacturing (AM) does not require a mould or tool to shape the surfaces of an object. Unlike cutting, AM techniques do not involve removal of material. They do have some similarities to certain joining processes, however, as you will see.
There is nothing fundamentally new about AM in principle. Building a house from bricks typifies the AM principle, as does building a model out of Lego bricks. The basic building blocks in both cases are simple rectangular shapes that can be fixed together to build up larger and more complex overall shapes (Figure 67). The regularly shaped blocks can be used to approximate features like curves. But the limit of definition is the size of the block. From a distance the assembly may appear to have smooth curves (Figure 67(a)). Look too closely (Figure 67(b)) and all you see are square edges. Smaller blocks can be used to create better approximations. But larger blocks allow you to build faster.
Someone who uses Lego blocks to make a model, or a mason who lays stone blocks in the shape of a building, has to 'imagine' the shape of their products before starting the construction and understand how the simple blocks can be used to create those shapes. Of course there is usually help at hand from drawings and written instructions.