New 3D metal printing technique combines lasers and advanced robotics
Mon 7 Sep 2015
While traditional 3D printing using fused deposition modelling (FDM) techniques becomes evermore commonplace, engineers are looking to develop further 3D printing technologies to widen its application within the manufacturing industry.
Selective Laser Sintering (SLS) is one of the key areas for 3D printing research, which uses laser beams to project and bind powdered materials, typically metal, creating solid 3D models.
However, a new alternative to rival SLS is being developed by a team of manufacturing researchers at the Southern Methodist University. Led by Professor Radovan Kovacevic, the group have presented a technique called Laser-Based Direct Metal Deposition (LBDMD) which builds on traditional FDM and laser technology to create high-quality metal objects as parts for a range of fabrication uses.
The team, based at the University’s Research Center for Advanced Manufacturing (RCAM), has been working on the new approach to metal 3D printing since 2005, when the centre was awarded a grant from the National Science Foundation for its research in laser and plasma-based manufacturing. An additional grant was received by the school five years ago. The University’s MultiFab system was awarded a patent in 2006.
The technology is still very much under development, but the researchers hope that LBDMD will offer a promising 3D metal printing solution for low volume demand, or for the repair and alteration of parts. The team has already secured interest from various sectors including car manufacturers, biomedical device companies and aerospace organisations.
As outlined by PhD student, Yaoyu Ding, the technique is inspired by traditional additive manufacturing building metals layer-by-layer. He explained that the machine forms a molten pool on a base using a laser beam into which it feeds the metal powder. It then performs subtractive techniques to achieve the final result set out by CAD files. In the YouTube video posted below the team illustrates its working prototype printing a metal propeller:
The technology differs from standard sintering techniques, as it uses multi-axial positioning robotics which eliminates the need for a support structure and human intervention, which inevitably slows existing methods.
“In our system, multiple-directional deposition was developed to eliminate the requirement for the support structures by using a multi-axis positioning system to orientate the substrate with respect to the laser cladding head. Owing to the synchronized motions of the robot and the positioning system, such system has potential to simplify the process planning and reduce production time,” said Ding of the axial solution.
To optimise the LBDMD technology further, Ding referred to a sensing and control system which monitors powder flow rate and the pool size of the molten area during printing, thus improving reliability and repeatability.
Ding added that size limitations do not apply as in typical metal sintering technologies. Additional machinery can also be used to aid the process during build, improving the construction of internal cavities and the surface quality.
Research and development continues, and no concrete plans are yet under way to bring LBDMD to a commercial context.