Additive manufacturing for on-demand parts replacement
To maintain their equipment, SNCF Mobilités and SNCF Réseau manage a portfolio of 200,000 part references. Additive manufacturing is offering new ways to optimize the procurement and storage of these parts.
“Two years ago, we launched a project on the additive manufacturing of metal parts to be able to supply spare parts with characteristics globally equivalent to the original ones”, explains Louis-Romain Joly, project manager on the Mechanical Systems and Interactions team at SNCF Innovation & Research. An important objective of this decision-support project is to identify the fast manufacturing line(s)* among eight shortlisted that would produce a maximum number of spare parts at the lowest cost and in the shortest time, thus reducing inventories while avoiding the immobilisation of equipment (trains or network equipment) when a part is lacking.
To do this, the research team first looked at the catalogue of SNCF Mobilités. “SNCF Mobilités logisticians have picked out 1,000 articles they consider critical either because they are susceptible to supply interruptions; or because they are not needed often (once or twice a year) but they have long lead times; or because the minimum order is too large”, says Joly. The result? “Although selective laser melting (SLM, see box below) would be the most versatile for the production of a large number of parts, we know it is expensive and too slow for large parts. This is especially important because we have to take into account the quasi-systematic finish machining phase and the logistical delays between the stages to have a precise idea of how long it will take for the parts to be available.” This technology can already be useful today, but it will be even more advantageous in the medium term thanks to ongoing developments. At this stage, the optimal approach for maximum efficiency seems to be combining three lines.
Additive manufacturing meets reality
A similar study has been underway at SNCF Réseau since early in the second quarter. In May, the project advanced with a full-scale test on three references with seven manufacturing lines. “In one case, we were able to keep the entire production cycle under seven days. That’s promising!” adds Joly. The next step? “We are setting up a working group with EDF, Airbus Helicopters, DCNS, DGA, CEA, Areva, and TOTAL for this project”, says Joly.
*The “line” is all the technological building blocks that must be assembled to manufacture functional parts.
The SLM manufacturing line
- 3D digitisation
- CAD reconstruction of the part
- CAD-CAM of the blank
- Additive manufacturing of the blank with SLM
- Finish machining