A method of 3D printing of more durable elements, developed by the US Army

With many advantages of FDM technology, one of the disadvantages, especially troublesome in the case of technical 3D prints, is the low mechanical strength. When designing an item, you can plan to a certain degree how it will wear or deteriorate, but in applications where long life of parts is a priority, it may be necessary to strengthen printouts by using specialized materials.

US Army scientists presented their own idea for creating more durable 3D prints. According to their concept, a solution composed of more than one polymer can solve the problem of low strength. The filament of their idea is a combination of two types of material, one of which is the core and the other the warp.

According to assurances, these materials can be successfully used for 3D printing of highly loaded elements on a low-budget desktop 3D printer. This solution, theoretically, can allow the production of components for specialized applications that comply with stringent requirements even in field military operations.

According to Eric D. Wetzel, coordinating research on composite materials at the US Army research center, developing a material that has increased mechanical properties while not requiring specialized manufacturing equipment is a kind of breakthrough. The optimal solution for military applications would be the possibility of 3D printing in the field, but so far the incremental production of durable parts required large industrial machines.

In their publication, scientists focused on FFF technology and creating materials adapted to this manufacturing method. The filament creation process includes the following stages:

• 3D printing of the preform using two equal materials to form the core and matrix – the example presented by scientists consists of ABS and polycarbonate,
• molding the preform filament using a thermal drawing process. The filament is created using a pilot production line, equipped with, among others in the basic diameter measurement system.

The filament prepared in this way can be used for 3D printing, just like standard materials. The creators point out that the finished element should be annealed in the oven to better merge the materials included in the filament.

According to the creators, the solution they developed allows 3D prints to compete in terms of strength with elements from the injection mold. In addition, easier access to durable 3D prints is combined with shorter waiting times, reducing it from weeks to hours. The project is still being developed and optimized – works are currently underway to reduce the annealing time to several hours.

Research into the creation of durable materials for 3D printing is described in the publication “Tough, Additively Manufactured Structures Fabricated with Dual-Thermoplastic Filaments”, which appeared in the latest issue of the scientific journal Advanced Engineering Materials.