German researchers are looking into using PEEK thermoplastic for medical implants. PEEK thermoplastic is a high performance material made of molecules that are both temperature and chemical resistant making it quite popular for a multitude of applications.
PEEK is also used in the medical field, it’s compatible with orthopedics, devices in the skull and antibacterial agents. Through the AM process it can be used in more complex devices and can viable scaffold bioprinting. The researchers are focusing on what parameters are best for printing small devices in PEEK material.
Using their own research and the research of 12 other researchers the concluded the critical factors of PEEK printing include.
- Raster angle
- Layer thickness
- Filling ratio
- Printing speed
Anyone who has done 3D printing knows the best path to successful printing is understanding the parameters and properties of the material. The researchers looked into the temperature and the feed rate of other researchers.
“Nozzle temperatures have been explored within a range from 340 °C to 480 °C. Wu et al. found when the nozzle temperature is 350 °C, the warping deformation of PEEK samples is minimal. Vaezi et al. identified nozzle temperatures of 400–430 °C as an applicable range,” stated the researchers.
“Nozzle temperatures below 400 °C caused either nozzle clogging or delamination of the final product, and above 430 °C resulted in either considerable filament deformation or material degradation. Hu et al. designed a new heater control nozzle module to improve the temperature uniformity in the printing area.”
They also looked at reducing the diameter of the nozzle for precise control for better part accuracy, but printing speed is an important factor that has to match the extrusion speed to avoid errors like sticking and clogging.
“Geng et al. investigated the effects of the extrusion and printing speed on the microstructure and dimensions of an extruded PEEK filament,” stated the researchers. “They performed the experiments with nozzle diameters of 0.4, 0.5, and 0.6 mm and printing speeds from 0.1 to 120 mm/min. They concluded that during the FDM of PEEK, the melt pressure directly affects the surface morphology and extrusion diameter of the filament, and higher melt pressure is beneficial for the reduction of surface defects on the extruded filament.
“Rahman et al. took a printing speed of 50 mm/s in their experiments while Han et al. applied a printing speed of 40 mm/s in theirs. Deng et al. achieved optimal tensile properties for PEEK specimens when the printing speed was 60 mm/s. According to the results above, we can assume that a reasonable speed value for the printing of PEEK with a 0.4 mm diameter nozzle should lie in the range of 40–80 mm/s.”
During the experiments the team printed several oversized dental implants internal and external structures, using the information they gathered as well as their own knowledge the prints were classified as unacceptable do to screw depth and porosity levels.
Hoping for better success the team moved to a 0.15 mm nozzle with improved success and a part that was acceptable.
“We got the best specimens with the 0.15 mm nozzle when printing the ×1.2 scale implant, which is acceptable in both the reproducibility and surface quality,” stated the researchers.
“Further improvement of samples with improved mechanical strength might count on the better solution of 3D printer technology and better manipulation of PEEK,” concluded the researchers.
“Until now, the printing of reproducible tiny-sized PEEK parts with high accuracy has proved to be possible in our experiments, which is achieved through optimization of the FDM printing parameters. There is still a long way to go to accomplish the transition from the research phase to 3D printed PEEK manufacturing, and finally to reach the goal of integrating the treatment within clinics. However, this trial might lay a basis for the patient-specialized treatment in the field of dental implantology. Considering the complexity of chewing forces, systematical mechanical tests are needed, and simulation based on finite element analysis is necessary for further research.”
O’Neal, Bridget. “FDM 3D Printing with PEEK for Small Medical Implants – 3DPrint.Com: The Voice of 3D Printing / Additive Manufacturing.” 3DPrint.Com | The Voice of 3D Printing / Additive Manufacturing, 21 Feb. 2020, 3dprint.com/263279/fdm-3d-printing-peek-small-medical-implants/.