Scientists at the Columbia School of Engineering and Applied Sciences have presented a method that allows you to print items from multiple materials. It used to be thought that it was too expensive and difficult.

One of the most popular techniques in 3D printing is selective laser sintering (SLS). In this case, the micron-scale powder is combined using a laser. It heats the particles to the point that they fuse together and form a solid mass. However, the method has its limitations: an item can only be crafted from one material.

The researchers decided to work around this limitation and changed the location of the laser inside the printer. Their working prototype, along with a print sample containing two different materials in one layer, is described in the scientific journal Additive Manufacturing, the text about this will appear in December 2020.

Selective laser sintering is a process in which material particles are bonded using a downward laser onto a heated printing substrate. The object is printed from bottom to top: first, the printer produces an even layer of powder and, using a laser, selectively melts the rest of the materials in the layer. Then the printer applies the second layer of powder to the first, the laser joins these materials; the process is repeated until the part is ready.

The researchers also found a way to print items without a powder base. They installed several transparent glass plates, each coated with a thin layer of plastic powder. They lowered the print bed to the top of one of the layers and directed the laser beam up through the bottom of the plate.

In this case, the printer prints with a portion of the powder according to a preprogrammed pattern. The platform is then lifted with the fused material and moved to another plate covered with another powder, where this process is repeated. This allows multiple materials to be combined into one layer.

The team showed a working prototype by creating items from thermoplastic polyurethane and multi-layer nylon. These parts are strong and dense, but the researchers plan to improve their properties in the future.