Researchers from the Polytechnic University of Milan (Politecnico di Milano) have developed a new patent-pending Selective Laser Melting (SLM) system capable of removing defective layers during a print job.
Dubbed PENELOPE, this prototype 3D printer combines SLM with a removal system to provide a new solution to the entire production chain. According to a thesis from Professor Bianca Maria Colosimo and Professor Marco Grasso from the Department of Mechanical Engineering at Politecnico di Milano: “3D printing still shows some technological limitations to overcome. One of the main challenges for research and development in this sector is the need to improve the stability, repeatability and capacity of printing systems.”
“There are several possible sources of error and various types of defects – internal porosity, residual stress, geometric deformations, micro-structural discontinuities, etc. – that may arise during the process,with a negative effect not only on the final quality and performance of the products, but also on production times and costs. This thesis work aims at the development of the first additive printing system, ensuring a first-time-right production.”
“The first SLM prototype with inline defect removal”
The PENELOPE system, which is said to be the first SLM prototype with inline defect removal, comprises of a surface grinding wheel and cart mounted on a linear axis, opposite to the Y-axis. The wheel component holds an average grain size of 120 µm, a maximum speed of 4,000 rpm, a max feed of 30 mm/s and a cutting depth of 10-20 µm.
In-situ infrared (IR) video imaging is used to monitor the plume formed through material evaporation and heating of the surrounding gas. Moreover, this technology is features pre-/post-exposure images, a 20 µm/pixel capacity, as well as a reconfigurable illumination system, fitted into the printer’s build chamber.
Using the integrated sensing and monitoring system, defects are identified and removed, then printing is resumed, for a faultless print. The researchers have tested the PENELOPE system which has effectively remove defective layers of during additive manufacturing.
Industrial metal 3D printing
Most recently, Award winning 3D materials manufacturer CRP Technology collaborated with the Department of Aerospace Science and Technology of the Politecnico di Milano (PoliMi) to construct wind tunnel aero-elastic demonstrators.
As well as the thesis, Professor Colisimo and Professor Grasso have co-authored “A statistical learning method for image-based monitoring of the plume signature in laser powder bed fusion,” published in Science Direct.
Featured image shows The PENELOPE system. Photo via Politecnico di Milano.