Guide: Material selection – Choosing the right polymer

Some materials are easier to extrude, print, recycle, than others.

Choosing the right polymer can save you a lot of research time.

1. Why care about material selection ?

The success of the 3d printing step depends on the 3d printer, the printings settings and conditions, the filament quality, and the material. The filament quality depends on the extruder, the extrusion settings and conditions, and the material.

A material should not only be chosen for its properties, but also for its processability.

For both the extrusion and printing step, choosing an appropriate material is essential.

2. Considering your application

It is crucial to define your needs precisely. Quite often, the material is a variable in the project.
When several materials tick all the boxes that you need, it might be wiser to choose the one that is easier to process.

Example 1 : If you need high mechanical and temperature resistances, PEEK is a famous option, but others exist : PEKK, PEI… And even looking at PEEK only, there are many grades of PEEK to choose from.

Example 2 : PP+copper powder. If the true focus of the project is the additive, copper, then you could maybe start by processing PLA+copper. PLA is a lot easier to extrude and to print than PP.

3. What is a grade of polymer ?

A grade of polymer corresponds to one specific reference of one polymer type by one manufacturer. Normally, each individual grade is associated to a precise technical datasheet.
For instance, “ABS” is a family of hundreds of grades of ABS.

Or even more precisely : Ingeo Biopolymer 4043D is a grade of PLA by NatureWorks.

4. How to differentiate grades ?

Every grade is unique, but we can classify them into big families of grades.

The main difference between these categories is the flowing behavior of the molten polymer, which can be quantified by one simple viscosity indicator : the Melt Flow Index (or Rate), in g/10min. The MFI test is quite simple : measuring what mass of molten polymer can be pushed through a hole, under standardized conditions. The higher the MFI, the more fluid the plastic is, the lower its viscosity.

5. How to choose the right grade based on the MFI ?

These MFI values are only estimations. This scale is a general indication to help you choose your first material if you have the option to choose, but it does not mean that only extrusion grades can be processed with our Filament Maker. At 3devo, we have successfully processed many injection grades.

Manufactured items typically do not have material technical datasheets. In that case, the MFI is unknown.

6. Extra: Certain materials are trickier than others for specific reasons

  • High temperature polymers like PEEK, PEEK, PEI,… require special processing, transitioning, and purging techniques. It is very important to learn the techniques before trying an experiment, to avoid clogging the Filament Maker.
  • PP and HDPE are difficult to solidify into round filament, because of their high crystallinity. They are very safe for the equipment but take time to master.

Before processing those materials, it is good to practice with PLA and get in touch with our team.