A new study from The University of Manchester has found that using slightly lower printing temperatures during a newer type of metal 3D printing can produce stronger, higher-quality aluminum parts with fewer tiny defects.
The findings, published in the journal Materials & Design, could help improve the reliability of metal 3D printing for industries such as aerospace, automotive manufacturing and engineering.
Metal 3D printing has become an increasingly important manufacturing technology because it allows companies to create complex shapes that would be difficult or even impossible to make using traditional methods.
It also reduces material waste because only the metal needed for the part is used. However, many current metal 3D printing techniques rely on extremely high temperatures and rapid heating and cooling.
These harsh conditions can leave behind small defects, internal stress and distortion that may reduce the quality of the finished product.
The research team focused on a newer manufacturing method called molten metal deposition (MMD). Instead of melting solid metal during the printing process, MMD uses aluminum that has already been melted before it is deposited layer by layer.
This creates a more stable printing process with gentler temperature changes, making it easier to control and potentially reducing energy use.
To better understand how temperature affects the quality of printed parts, the researchers used aluminum alloy 4043, a material commonly used in manufacturing and engineering.
They printed test samples using different nozzle temperatures and different temperatures for the surface on which the metal was deposited.
After printing, they carefully examined the internal structure of the samples using powerful microscopes and carried out mechanical tests to measure their strength and stiffness.
The study showed that higher printing temperatures caused the aluminum to cool more slowly. This slower cooling created larger metal grains inside the material and increased the number of tiny air pockets, known as pores. These microscopic holes can weaken a component if too many are present.
When the printing temperatures were lowered, the aluminum cooled more quickly. Faster cooling produced a finer internal structure and significantly reduced the number of pores. This resulted in cleaner, more uniform material with fewer defects.
The researchers also noticed that as additional layers were printed, both the grain size and the number of defects generally became smaller.
This suggests that the temperature conditions naturally change throughout the printing process, influencing how the metal solidifies from one layer to the next. The team also found a close relationship between grain size and the amount of porosity, providing valuable clues for improving future printing methods.
Although some small defects remained in the printed samples, the finished parts performed surprisingly well.
Their hardness and stiffness were similar to aluminum alloy 4043 parts made using conventional manufacturing techniques, showing that molten metal deposition already has promising practical performance.
The researchers say there is still much to learn about this relatively new printing technology, but their work provides important guidance for improving print quality.
By carefully adjusting printing temperatures, manufacturers may be able to produce aluminum parts that are more reliable, more consistent and better suited for demanding industrial applications.
As metal 3D printing continues to develop, these findings could help make the technology more efficient and attractive for large-scale manufacturing.
At the same time, the study highlights that even small changes in printing conditions can have a major impact on the final product, offering manufacturers a simple way to improve quality without changing the material itself.
