Tolerance Analysis of 3d-MJM parts according to IT grade

In this study we investigate the dimensional accuracy of 3D printed objects and define the International Tolerance (IT) Grade for the linear sizes of parallel opposite surfaces and the diameter of a cylinder. Eight (8) exact parts were printed by an Objet Eden250 3D printer using the Multi Jet Modelling (MJM) process. The printed objects were measured and their dimensions analysed to define the IT grade of the specific process. MJM is an Additive Manufacturing (AM) or 3D Printing manufacturing process that can be used in place of CNC to save weeks of lead time, allows us to create parts with a superior strength to weight ratio and can significantly improve the efficiency of the completed system. MJM process is used for a great variety of applications on concept models to model performance parts as functional prototypes, jigs and fixtures, manufacturing tooling and sometimes even production parts. The result of this investigation is that the MJM 3D printing process can produce objects with IT11 grade or better, which classify it to the Fits area of IT grades.