DSM has developed a small family of semi-crystalline thermoplastics for FFF 3D printing, including grades of Novamid ID polyamide 6 and 6/66, Arnite ID PETP and Arnitel ID thermoplastic bio-based co-polyester elastomer. As a major developer and producer of engineering plastics for many processes and applications, DSM understands that a deep insight into the 3D printing process is key to understanding material behavior and this insight is leading the company to develop products quicker and more accurately.
With the current state of FFF 3D printing, the mechanical capabilities of the technology are exceeding their thermodynamic capabilities. Printers can reach speeds of up to around 300 mm/s, however in many cases when engineered thermoplastics are used, the mechanical properties of the finished parts are inadequate because of poor inter-laminar strength caused by poor thermal bonding.
The principal problem is that while the printing equipment is highly capable of depositing the filament very accurately at a high speed, the equipment’s capacity does not match this ability to melt the polymer sufficiently. Next to this, a controlled print chamber helps to print with lower warpage of the part.
To raise the temperature to this point, heat is added from the surface of the nozzle with an external heater block. As already mentioned, the thermal conductivity of a polymer is low (0.3 w/mk). Therefore, it will take some time to reach a homogeneous temperature distribution at the nozzle exit. Using numerical simulations of the heat balance in a frequently used hot-end, a “v6” from UK 3D printer component supplier E3D, it is possible to demonstrate how much the homogeneity of the temperature distribution decreases with increasing printing speed.