New 3D printing technique reduces part deformation

Researchers at the University of Michigan have developed software that allows for improved 3D printing by reducing the harmful heat build-up in laser powder bed fusion printers. The new technique optimizes the laser's printing path by intelligently guiding it to avoid unnecessary heat build-up, and means such 3D printers could fabricate complex metal and plastic parts much quicker.

Laser powder bed fusion is a type of 3D printing where a laser fuses layers of powdered metal or plastic together, and is mainly used in the aerospace, automotive and biomedical industries for parts that are too intricate for conventional manufacturing. A problem with this additive manufacturing (AM) approach is the heat from the laser can build up in the parts being printed, resulting in deformation, defects and residual stress, especially for those with very thin features.

However, as reported in Additive Manufacturing [Ramani et al. Addit. Manuf. (2022) DOI: 10.1016/j.addma.2022.102643], this technique speeds up the manufacturing process by reducing the need for printers to slow down to assist cooling, and also the defects that have be corrected after printing. This is the first application based on a thermal model to guide the laser to distribute heat more evenly, and was shown to achieve a 41% improvement in heat distribution and a 47% reduction in deformations.

The team have been investigating metal AM in terms of advanced software and control techniques to improve quality, speed and cost-effectiveness. Their software, called SmartScan, takes into account how heat flows within a given part and analyzes the shape of the part and the thermal properties of the material being used, before mapping an optimized scan sequence to reduce heat accumulation in that area.

To investigate its effectiveness the team used a laser to imprint an identical pattern on two stainless steel plates, using the SmartScan process for the first plate and then switching to traditional printing patterns for the second. The first prints were consistently less warped, and demonstrated more uniform heat distribution during the marking process than the other plate methods. As corresponding author Chinedum Okwudire told Materials Today, “This research will help reduce defects in metal AM and reduce the time and cost spent on post-processing to correct defects”.

The team hope to add laser power and speed control to the process to make it more powerful, and are working to expand the approach to multi-laser AM systems, and to leverage their method to not only prevent defects but also tailor material properties in useful ways. They also hope further work on the process will allow the software to build full 3D parts.

“This research will help reduce defects in metal AM and reduce the time and cost spent on post-processing to correct defects”Chinedum Okwudire