Abstract :
[en] Despite the growing adoption of Additive Manufacturing in the industry, it still lacks standards to evaluate the dimensional and geometrical performance of printers for long production runs. This is especially needed to foresee the required post finishing operations by knowing which quantity of material should be removed from the parts after their fabrication (by finish milling, for example). ISO 52902, by proposing to design, print and measure test artifacts, allows the tolerance intervals achievable by a printer to be obtained. Nevertheless, this method leads to long printing times (27 h of printing are common values for one part). This makes this method not suitable for industrial purposes if a capability analysis is needed and would lead, therefore, to very high production times (nearly 1 month to produce 25 parts).
In this presentation, we propose a novel part design called the COMPAQT (Component for Machine Performances Assessment in Quick Time) that allows to determine the achievable dimensional tolerances of a printer, while keeping the required printing time lower than 24 h for producing the required 25 parts. Moreover, the COMPAQT, when replicated 25 times over the available building platform area, provides a systematic coverage of the achievable size ranges of ISO 286-1.
The COMPAQT can be used either to evaluate the capability of a printer by replicating it and covering most of the available printing area (in X and Y), or to track the performance degradation of a printer in the longer term by adding one COMPAQT into batches as a companion part. The method was successfully tested on a commercial Material Extrusion machine printing poly-lactic acid feedstock and allowed its potential and real tolerance interval capabilities to be evaluated. ISO 22514 was used to analyze the data and obtain the capability indices.
Different tolerances were obtained for the measurements according to the X, Y and Z axes, the latter exhibited the best performance. Finally, different systematic errors were observed, depending on whether the measurements involved surfaces of a single (values around 0 mm) or two different COMPAQT parts (values up to 0.314 mm).
