Benchmarking of FDM Machines through Part Quality Using IT Grades

The diffusion of Fused Deposition Modeling (FDM) was recently boosted by the expiration of the FDM patent and the subsequent worldwide development of low cost FDM machines by a huge number of small companies. In most of the cases, FDM machines are worth what they cost. Thus the performance of expensive industrial FDM systems is better than that of low cost machines, also known as 3D printers. In this paper a benchmarking is carried out between a Dimension EliteTM by Stratasys and a 3D TouchTM by Bits from Bytes (BFB). The study and comparison is based on a reference part that was designed to fit into the building volume of most of low cost FDM machines. The part includes several classic geometries (planes, cylinders, spheres and cones) of different sizes to cover several ranges of basic sizes as defined by the ISO 286 standard. Geometric features appear both in the concave and convex shapes to account for all design possibilities. The proposed reference part allows to consider a higher number of features for each range of basic sizes with respect to other benchmarking models presented in the literature. Moreover the part does not require support structures for its production, allowing for manufacturing on 3D printers that come with a unique extruder. Replicas of the reference part are printed out of ABS (acrylonitrile butadiene styrene) material with different layer thicknesses using the compared machines. After inspecting the replicas by means of a Coordinate Measuring Machine (CMM), the dimensional accuracy of the compared FDM systems is reported through part quality using IT grades associated with the ISO basic sizes. GD&T values are also evaluated for some of the geometric features appearing on the reference part.