Additive manufacturing: controls

Commonly referred to as 3D printing, additive manufacturing (AM) is a real revolution, as it overcomes the limitations of traditional manufacturing (plastic injection, machining, forming, assembly). In fact, it gives us the latitude to manufacture highly complex parts that would be impossible to produce using other techniques, opening up new prospects for innovation. However, the mainstream press tends to present FA as a press-button technology, accessible to all. The reality is quite different.

In FA, the material and the part are manufactured simultaneously, layer by layer, from a digital model. But making a part is not simply a matter of transferring a digital drawing to the machine, pressing a button and waiting for the part to be manufactured. There are many steps both upstream and downstream. The complete process includes part design, machine preparation, machine set-up, part manufacturing and post-processing. Part design comprises a number of stages: selection of the material and structure (solid or lattice); design of the digital model describing the part geometry, with or without topological optimization; discretization of the part surface; positioning and orientation of the part, or parts, on the manufacturing table; part support and cutting of the digital model into strata representing the layers to be produced. Depending on the process, machine preparation includes cleaning the machine, loading the raw material, possibly homogenizing and leveling it on the bed of the manufacturing chamber, and adjusting the height of the leveler.

Configuring the machine involves setting its parameters; for example, in the case of the laser powder bed melting category, choosing the laser's scanning speed, power, beam size, scanning strategy and number of leveler passes. And don't forget to record input data to ensure traceability of the manufacturing process. At the end of the process, the part must be extracted from the unprocessed raw material and cleaned. Next, the part is heat post-treated. Depending on the process, this involves annealing to eliminate residual stresses, or to perfect the bonding process of the raw material, or to loosen the part. Finally, the part is detached from the machine's manufacturing table, its supports are cut, its surface finish improved and it is cleaned. As well as demonstrating the need to review design procedures, these numerous steps highlight the complexity of the process.

Consequently, before FA can be adopted by manufacturers, especially those involved in small series production (aeronautics, aerospace and medical), it is essential to qualify the machines and demonstrate that the parts produced by FA meet the same quality requirements as those produced by traditional techniques. To achieve this, it is necessary...