Technology based on additive manufacturing is rapidly emerging and is being used in a wide range of industries. Meeting the precision and accuracy (P&A) requirements of 3D printed parts (shape and size tolerances, surface quality, etc.) is increasingly becoming an issue. This paper presents a critical analysis of the tribological problems encountered in 3D printing for parts manufactured through different types of technologies, such as powder bed fusion, binder jetting, direct energy deposition, material jetting, fused filament fabrication, vat photopolymerization, sheet lamination, and ultrasonic consolidation. For all these additive manufacturing technologies, this paper will present a brief description, classification, examples of materials used, and tribological problems of the obtained machine parts.

Technologies such additive manufacturing are slowly becoming more and more present on the market, covering different areas of the industry due to its great potential. Even so, there are still many aspects which are unexplored or which can be improved. One of them being the study of the tribological proprieties for all these parts, which are produced through additive manufacturing methods, such as powder bed fusion, binder jetting, direct energy deposition, fused filament fabrication, material jetting, vat photopolymerization, and sheet lamination. The scope of this paper is to bring together the tribological proprieties for the 3D printed parts, and to have a critical analysis of these proprieties, in order to easily decide which printing method is suitable, depending of the working conditions of the printed component. In addition, this paper will describe the working principle for each technology, and the type of materials that are commonly used in the printing process. Depending of the printing method, the tribological proprieties vary greatly. For example, for the parts which are manufactured through powder bed fusion, it was found that the wear resistance is higher, and with a lower friction coefficient than for a part manufactured through traditional methods. In addition, for many printing methods, the produced part might require an additional step of treatment. This is the case with binder jetting, where infiltration and sintering are often used because the 3D-printed part is porous and weak. Some researchers found that the average friction coefficient measured for a steel-based part, treated with bronze infiltration, is comparable with the friction coefficient measured on a part made of the same material, manufactured through the direct energy deposition method. Of course, due to the physical limitations of the 3D printing method, the system will allow only the usage of a specific type or class of materials. One of such method is fused filament fabrication, where only thermoplastics are used. Along with vat photopolymerization and material jetting, these methods present comparable tribological proprieties.