Standards enabling the objective tolerancing and evaluation of dimensional and geometrical performances of additive manufacturing (AM) printers are still missing. The design, printing and measurements of geometrical benchmark test artefacts (GBTA) is the current solution proposed in literature. However, the current GBTA with fixed dimensions cannot cover most of the available printing area of printers with large building platform dimensions. This article proposes to solve this problem by developing an adaptive GBTA design whose main dimensions can be adapted to any common 3D printer. Moreover, an innovative design is implemented to decrease the risk of warping. The adaptive GBTA will then be used to characterise the performances of two different architecture material extrusion printers (Ultimaker 2+ and Pollen AM Series MC). Dimensional and geometrical accuracy, as well as top surface topography, were evaluated. The Ultimaker printer could reproduce features with maximum deviations below the tolerance interval (IT) 13 of the ISO 286-1, while the Pollen machine achieved a higher IT of 15 or 16. The highest geometrical deviations were observed for the coaxiality of cylinders oriented along the build direction (Ultimaker: 0.250 mm and Pollen: 0.497 mm). Top surface topography exhibited higher Ra values for Pollen (13.7 µm) than for Ultimaker 2+ (4.9 µm). The performances of the Pollen printer were lower than the Ultimaker machine in terms of surface topography, dimensional and geometrical accuracy. The proposed adaptive GBTA design covers most of the printing areas exhibited by Pollen and Ultimaker printers and offers flexibility to test other printers even with larger or smaller dimensions.

The performance assessment of additive manufacturing (AM) printers is still a challenge since no dedicated standard exists. This paper proposes a systematic method for evaluating the dimensional and geometrical performance of such machines using the concept of machine performance. The method was applied to an Ultimaker 2+ printer producing parts with polylactic acid (PLA). The X and Y axes of the printer were the most performant and led to narrower potential and real tolerance intervals than the Z axis. The proposed systematic framework can be used to assess the performance of any material extrusion printer and its achievable tolerance intervals.

Manufacturing of advanced ceramic parts exhibiting complex geometries is laborious and expensive. Traditionally, the machining is carried out on a so-called ‘green ceramic’: a compact composed of ceramic powder held with the help of a binder. This difficulty is due not only to the composition of the material, but also to the lack of methods that determine optimal machining parameters. The goal of this paper is to apply the method based on ductile material behavior to determine a feed rate working range to ensure a machining quality. Indeed, a previous study demonstrated the limits of this method in determining cutting speed. In this case, two material removal mechanisms are observed: a mechanism dominated by pulling of the material and a proper machining mechanism. This demonstrates that the specific cutting energy is a reliable indicator for machining quality assessment. In the studied case, the recommended machining parameters to ensure quality machining of Y-TZP green ceramic with a 3 mm diameter cylindrical tool are: a cutting speed of 250 m/min, a feed per tooth of 0.037 mm/tooth, an axial depth of cut of 0.7 mm, and a radial depth of cut of 3 mm.

Additive manufacturing (AM) opens new possibilities of obtaining ceramic green parts with a tailored complex design at low cost. Meeting the requirements of highly demanding industries (aeronautical and biomedical, for example) is still challenging, even for machining. Hybrid machines can solve this problem by combining the advantages of both additive and subtractive processes. However, little information is currently available to determine the milling parameters of additively fabricated ceramic green parts. This article proposes a systematic approach to experimentally determine the cutting parameters of green AM zirconia parts. Three tools, one dedicated to thermoplastics, one to composites, and a universal tool, were tested. The tool–material couple standard (NF E 66-520-5) was followed. The lower cost and repeatable generation of smooth surfaces (Ra < 1.6 µm) without material pull-out were the main goals of the study. The universal tool showed few repeatable working points without material pull-out, while the two other tools gave satisfying results. The thermoplastic tool ensured repeatable results of Ra < 0.8 µm at a four times lower cost than the composite tool. Moreover, it exhibited a larger chip thickness range (from 0.003 mm to 0.036 mm). Nevertheless, it generated an uncut zone that must be considered when planning the milling operations.

Material Extrusion (MEX), particularly Fused Filament Fabrication (FFF), is the most widespread among the additive manufacturing (AM) technologies. To further its development, understanding the influence of the various printing parameters on the manufactured parts is required. The effects of varying the infill percentage, the number of layers of the top and bottom surfaces and the number of layers of the side surfaces on the tensile properties of the printed parts were studied by using a full factorial design. The tensile test results allowed a direct comparison of each of the three parameters’ influence on the tensile properties of the parts to be conducted. Yield strength appears to be the most affected by the number of layers of the top and bottom surfaces, which has twice the impact of the number of layers of the side surfaces, which is already twice as impactful as the infill percentage. Young’s modulus is the most influenced by the number of layers of the top and bottom surfaces, then by the infill percentage and finally by the number of layers of the side surfaces. Two mathematical models were considered in this work. The first one was a polynomial model, which allowed the yield strength to be calculated as a function of the three parameters mentioned previously. The coefficients of this model were obtained by performing tensile tests on nine groups of printed samples, each with different printing parameters. Each group consisted of three samples. A second simplified model was devised, replacing the numbers of layers on the side and top/bottom surfaces with their fractions of the cross-section surface area of the specimen. This model provided results with a better correlation with the experimental results. Further tests inside and outside the parameter ranges initially chosen for the model were performed. The experimental results aligned well with the predictions and made it possible to assess the accuracy of the model, indicating the latter to be sufficient and reliable. The accuracy of the model was assessed through the R2 value obtained, R² = 92.47%. This was improved to R² = 97.32% when discarding material infill as an input parameter.

Experimental evaluation of the maximal force before debonding a part from the build platform of an AM printer SPITAELS Laurent, ALDEITURRIAGA OLABARRI Naiar