Why the right material is so important in 3D printing

The choice of materials is one of the most basic steps when 3D printing.

After all, this choice can determine, among other things, the printing technique and subsequently the maximum achievable properties of the workpiece. These properties extend beyond obvious things such as strength, stiffness and elongation at break.

One of the first questions one should really ask is what is the part going to be used for? If it is a prototype, very different requirements apply than a functional part in a machine that is not even visible. Resins, the liquid, light-sensitive materials for, for example, printers Stratasys Origin One (DLP) or RPS (SLA), are characterized by the detailed representation of small features in the printed workpiece because they print with much thinner layers than other techniques. However, the very good level of finish is offset by mechanical properties that are slightly lower for standard materials than certain filaments for an FDM printer. This latest technology offers a much wider range of plastics to choose from. But the surface quality cannot match that of the DLP printers. And with powders, such as those for Stratasys' SAF printers, other things have to be taken into account.

Other features

FDM technology probably offers the largest choice materials . The range of filaments is very wide, from standard plastics to advanced high-end materials. Keep in mind that properties of 3D printed materials differ from those of plastics processed with traditional techniques. For example, nylon has a lower tensile strength with 3D printing than with injection molding. Material developers are trying to bring these properties closer together with additives. But differences remain: nylon 3D printed with a Fortus 900 mc printer has a tensile strength of 49 MPa (in the X-Y plane); nylon processed with traditional techniques has a tensile strength of 70 MPa. The strength of a workpiece printed with filament is partly determined by the geometry and the printing direction. In the Z direction, in which the layers are stacked on top of each other, the strength is slightly lower than in the X-Y plane. So take this into account in the design and when slicing, then a slightly lower strength does not have to be a problem. And otherwise there are plenty of good alternatives.

With or without fibres

In mechanical engineering, for example, many aluminum parts can best be replaced by 3D printed plastic parts. What one often sees is that plastics are used that are partly filled with short (glass) fibers, such as nylon (PA12) with carbon fibers . This material can be 3D printed just as reliably and reproducibly as PLA or PETG with the specially designed 3D printers from Stratasys' Fortus line. The short fibers provide extra strength and stiffness. The downside is that the nozzle of the 3D printer must be able to process these more aggressive materials. The choice of material therefore determines the choice of printer. This also applies if you want to print with real engineering materials such as PEEK and PEKK. These temperatures require much more thermal load than the 3D printer than the standard materials. Stratasys 3D printers such as the Fortus line can handle these temperatures (up to 350 degrees in the extruder and 230 degrees C in the build chamber). These materials are stronger than metal and weigh much less. The aerospace and medical sectors, among others, appreciate these properties. The printed parts have very good mechanical properties. But 3D printing with these materials does require experience and the right hardware.

Certification or not?

The choice of materials for 3D printers is wide nowadays. However, there is one aspect that can quickly and drastically limit the choice. We are talking about certification here. Stratrasys supplies several certified materials for various printers, for example approved for specific medical applications. These are for example the FDM or Objet printers medically approved materials that may make direct skin contact for a longer period of time. For an aircraft manufacturer such as Boeing, Stratasys supplies plastics for FDM printers that have been validated for the production of MRO parts for aircraft.

Personal advice

3D printing is a catchall concept. A lot can be achieved with the right combination of material and 3D printer, but the same applies vice versa. A wrong choice of materials can lead to disappointment. Therefore, do not hesitate to consult the 3D printing experts at Seido Systems. They are happy to help you select the right 3D printing technology and material, based on the application you have in mind.