Direct metal laser sintering: Rebuild, don’t replace

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Innomia and Ecoparts do see a few limitations to using DMLS, however: (1) current chamber size (250 x 250 x 325 mm) limits the size of parts that can be repaired; (2) surface finish is rough (about 10 Ra), requiring conventional finishing processes; (3) the layer-by-layer process demands a flat surface; and (4) only one material (1.2709) currently is approved for tooling. However, the high accuracy and surface quality after finishing that DMLS offers make it an ideal platform for tooling applications, including tool repair. Also, inserts repaired using DMLS are proving to prolong tool life.

Kundig adds that part complexity also is not a cost driver with DMLS. “Simple or complex structure, free-form shape or conformal cooling, the industrial 3D printer just manufactures the part,” he says.

Growing demand for DMLS to repair mould inserts

Both Innomia and Ecoparts have seen growing demand for the use of DMLS to repair mould inserts, as it simplifies and speeds the repair process. Instead of replacing inserts, both companies remove only the damaged material for their customers. In most cases, this alternative to completely remanufacturing an insert saves weeks in production time.

Hybrid production service for toolmakers

According to Rozkosny, Innomia initially ventured into metal additive manufacturing with rapid prototyping of automotive metal components but then moved to injection mould applications, including rapid tooling and conformal cooling. Since then, customers have come to trust the quality of DMLS parts in production tooling, he says, so demand for fast tool repairs grew very quickly.

When it comes to tool repair, Innomia uses not only DMLS, but also 3D scanning and reverse engineering. This allows the company to repair damaged tools, even when 2D or 3D documentation is unavailable. For one particular repair on a broken injection mould insert, there were no existing 3D data or drawings, and limited parts in stock.

“The insert was removed from the tool and delivered to us,” Rozkosny explains. “First we scanned the insert geometry and redesigned the complete 3D model. Then we cut or milled off the damaged area because we needed a flat surface to start the rebuilding process. The insert was then placed into the EOSINT M 270 system and positioned, and the missing material was laser-sintered on the cut surface. Next, the surface was finished and the insert was mounted back into the mould.” The job, from insert removal to production restart, was completed in three shifts, and the repaired insert has been in use for two and a half years now, demonstrating the repair’s quality and durability, he says. ETMM

This article first appeared in Additive Manufacturing, additivemanufacturinginsight.com, reprint courtesy of Gardner Business Media, Cincinnati, Ohio, US.

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