Dimensional accuracy and resolution assessment of the formlabs form 3B 3D printer for medical applications

• Design of a phantom to assess accuracy and resolution of a Formlabs 3D printer • The phantom includes specific features common for surgical guides • The dimensional accuracy is dependent on the printing orientation • The dimensional accuracy varies between -0.2mm and 0.4mm • A reference for the printing accuracy for a medical grade resin is provided For quality management of in-hospital 3D printing, it is essential to have detailed knowledge on the accuracy and reproducibility of the 3D printing process. In this study, the influence of several printing and post-processing parameters on dimensional accuracy and resolution were evaluated in three different hospitals to provide a reference for printer performance for medical applications. A custom phantom was designed comprising features to assess accuracy and resolution of the Form 3B printer (Formlabs, Somerville, MA, USA). Specific features common for surgical guides were included, such as slits, flanges, and cylinders. The phantoms were 3D printed using a medical grade resin (Formlabs Biomed Clear resin) and evaluated after postprocessing and sterilization. Dimensional accuracy was defined as the deviation between the actual measurement and the known feature dimension and evaluated in x-, y- and z-direction. Resolution was defined as the smallest complete feature. The accuracy of the prints in the x-direction varied between -0.1mm and 0.1mm, in the y-direction between -0.25mm and 0.4mm and in the z-direction between -0.2mm and 0.4mm. The influence of sterilization on the accuracy was negligible. The smallest slit that was always open when printing in the x-direction was 0.3mm and in the y-direction 0.4mm. This study provides hospitals with a reference for the printing accuracy and resolution for a medical grade resin. The phantom designed can be used in every hospital to determine their own printing accuracy and tolerances thereby optimizing product design for the intended clinical application.