## 1 Introduction
Compared with conventional processes such as injection molding, additive manufacturing via FFF (also known as Fused Deposition Modeling, FDM) enables the production of functional parts in a fast and cost-effective manner, especially for prototyping or smallbatch production [22]. This technology eliminates the need for molds or tooling, reduces initial costs, and allows for rapid design iteration. Its ability to manufacture complex or customized geometries makes it a suitable alternative when flexibility and personalization are prioritized over mass production. Despite the numerous advantages offered by FFF, one of its most notable limitations is the poor surface finish of the printed parts. Due to the layer-by-layer deposition process, surfaces often exhibit visible layer lines, step effects, and texture variations, especially on sloped or curved geometries [23]. These surface irregularities can compromise the functionality of the part in precision assemblies or in applications where smooth surfaces are critical [24]. A common strategy for improving surface quality in FFF is to reduce the layer height. However, the total printing time increases significantly as more layers are required to build the same geometry [25]. This trade-off between surface quality and production efficiency limits the scalability of the process, particularly in industrial contexts where time and cost are critical factors. Therefore, the application of complementary post-processing solutions can improve surface quality without negatively impacting the manufacturing process. In this sense, machining can be considered as a viable post-processing strategy to improve the surface finish and dimensional accuracy of FFF manufactured parts, producing smooth surfaces and fine tolerances in a reduced manufacturing time. This makes machining an effective and flexible post-processing solution, particularly when it is essential to maintain both mechanical integrity and surface finish. Machining processes have been extensively studied in the context of metals [26; 27; 28]. Nevertheless, there is significantly less research focused on the machining of polymers, especially those produced by additive manufacturing. Polymers exhibit different behavior under cutting conditions due to their lower thermal conductivity, viscoelastic properties, and heterogeneous microstructures [29]. In this context, the concept of machinability provides a comprehensive framework for evaluating how a material responds to machining. The assessment of machinability includes not only the resulting surface quality, but also the thermal and mechanical loads generated during the process, as well as its energy efficiency [30; 31]. These parameters provide valuable insight into both the performance of the machining process and the response of the material and can be used to optimize cutting conditions for improved results. The literature shows a set of research that evaluates the machining of PLA samples obtained by different manufacturing processes. The PLA components milling has been studied, particularly regarding the effect of cutting parameters on surface quality and structural performance. It has been observed that increasing the cutting speed tends to reduce cutting forces, although it may lead to a deterioration in surface finish due to thermal softening effects [32]. Conversely, higher feed rates consistently result in greater surface roughness. In the case of FFF-printed PLA, fine milling operations have proven effective in reducing roughness, and regression models have been developed to predict roughness values based on process parameters [33]. Milling has also been shown to significantly improve surface finish; however, it can negatively impact mechanical strength when material is removed close to the load-bearing outer perimeter of the printed part [34]. Drilling has also been considered in the machining of PLA.