Laser additive manufacturing targets larger stainless steel components

VILA NOVA DE GAIA, PORTUGAL – Additive manufacturing technologies are increasingly allowing the manufacturing of parts with geometries not achievable. In the case of laser powder-bed fusion (LPBF) technology, the SLM-XL project has taken the parts-size shortcoming and produced large 316L stainless steel parts over 1 m.

The project included the development of a prototype machine for larger parts using LPBF technology with a breakthrough technology, tiled laser melting (TLM), that is paving the way for the seamless production of small to large parts for the most demanding usage scenarios. Printing large-scaled parts with LPBF provides a fast and efficient way to create low-volume parts of any length and height (FIGURE), allowing flexibility in design and overcoming disadvantages of traditional manufacturing technologies.

The project has produced samples on the customized LPBF machine with relative densities above 99%, with the best result at 99.655%. This is a positive indicator towards the ultimate goal of zero-defect additive manufacturing in producing large components with LPBF.

The SLM-XL project was led by equipment manufacturer Adira Metal Forming Solutions, with the collaboration of research organizations Instituto Superior Técnico (Lisbon, Portugal), the Universidade Nova de Lisboa – Faculdade de Ciência e Tecnologia (Almada, Portugal), and the Institute of Science and Innovation in Mechanical and Industrial Engineering (INEGI; Porto, Portugal), as well as end user Manuel Conceição Graça (MCG; Carregado, Portugal).

This specific prototype includes a TLM printing process technology developed by Adira. To produce larger parts, the project brought the broad utilization of LPBF into the mainstream, with clear benefits in efficient resources utilization, cost-effectiveness for customized smaller production runs, and overall flexibility on the production. The project’s outcomes included a methodology for selection of parameters to fabricate large metal parts in stainless steel 316L, as well as contributing to the development of the final prototype machine.

Laser powder-bed fusion is a layer-by-layer process in which a defined powder thickness is melted by the laser, allowing the manufacture of functional complex-shaped objects with high structural integrity for low volume and affordable costs in different materials. Being able to deliver parts produced through this technology has already been used for biomedical devices. But ensuring the production of larger parts, retaining the expected features of materials made from traditional subtractive manufacturing, has proven elusive so far. By showing the capability of producing large build envelopes of 316L stainless steel samples, the project has paved the way for other materials to follow in the near future. To achieve the results of 99% plus density in the whole part, it was required to adjust the parameters at the outer zones, and a methodology to perform this adjustment has also been proposed as an outcome of this project.

For more information, please visit www.adira.pt and aai.tecnico.ulisboa.pt.