# Tribological Analysis of Fused Filament Fabrication PETG Parts Coated with IGUS  
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producing short and customised runs as it does not require expensive moulds or specific tools [4]. Additionally, the properties of the resulting parts can be controlled, although they largely depend on the printing process parameters. Optimising part orientation, fill density and pattern, layer height, and extruder temperature can result in significant improvements in the strength and stiffness of printed parts. The ability to adjust these parameters offers considerable flexibility to tailor the mechanical properties of FFF parts to the specific needs of various applications. Thus, parts printed in an orientation with \(+45^{\circ}/-45^{\circ}\) fill angles have shown higher tensile and impact strength compared to other orientations. This finding is significant because the print orientation can be optimised to enhance mechanical properties based on specific application needs [5]. On the other hand, another crucial variable is the fill density. It has been shown that a higher fill density generally results in higher mechanical strength. For example, an 80% fill density has been shown to significantly improve the tensile and flexural properties of printed parts. The choice of fill pattern is also influential, with more uniform patterns providing better results in terms of stress distribution and deformation [6]. Layer height is another parameter that affects the mechanical properties of FFF parts. Thinner layers tend to improve dimensional accuracy and mechanical strength due to better layer adhesion. However, printing with thinner layers increases printing time, which can be a limitation in the rapid manufacturing processes [7]. Additionally, extruder temperature and print speed also play significant roles. Optimal extruder temperature ensures proper material fusion, contributing to better layer bonding and, consequently, higher mechanical strength. On the other hand, an appropriate print speed is necessary to maintain a balance between print quality and the mechanical integrity of the part [8]. However, most studies address static mechanical properties but the dynamics of the parts are vital for their industrial implementation. Among these properties is the fatigue resistance of FFF parts, which is an important consideration for structural applications [9]. However, few studies address the tribological behaviour of FFF parts, although it is an area of study that is gaining attention [10; 11]. This may be due to the inherent roughness of additive processes conditioning this tribological behaviour, making its study especially complex. Although the limited existing information generally shows that FFF parts exhibit higher friction coefficients and wear rates due to the inherent roughness of surfaces fabricated by this process [12]. This is important as it may mean that manufacturing parameters such as layer thickness, fill pattern, and fill density have a significant impact on the wear rate and friction coefficient. Thus, it has been observed that a greater layer thickness contributes to higher wear resistance due to the greater amount of material that must be worn down to reach the substrate [13]. Print orientation also plays a crucial role in the tribological properties of 3D-printed parts. Parts printed in vertical orientations tend to have less wear depth, but higher friction coefficients compared to parts printed in other orientations [14]. However, other parameters are tremendously relevant, such as the nature of the materials themselves, and this is another advantage of FFF as it is possible to use advanced materials such as reinforced and composite filaments that offer improved mechanical and thermal properties. These materials allow for the creation of parts that can withstand extreme use conditions, further expanding the applications of this technology [15].