In recent years, additive manufacturing, especially 3D printing, has been gaining more space in the production of parts and components in various industries. Among the polymer materials, polylactic acid (PLA) stands out due to its renewable sources, such as corn starch or sugar cane. This study focused on the evaluation of the coefficient of friction (CoF) and wear resistance of pins of pure PLA, pure thermoplastic polyurethane (TPU), and bronze‐filled PLA (BRO), all produced by fused deposition modeling (FDM). The pins were rubbed against a SAE 1020 steel counterpart in a pin‐on‐disc apparatus. The wear tests also included combinations of BRO/PLA and TPU/PLA (with a pattern on the surface), combined at three different percentages (25%, 50%, and 75%). Pure BRO showed the lowest wear rate ( K ≈0.9 × 10 ⁻⁵ mm ³ /N m), while pure PLA exhibited the lowest CoF among the pins ( μ ≈0.24) but the highest wear ( K ≈16.7 × 10 ⁻⁴ mm ³ /N m). The combination of 75% of BRO with 25% of PLA demonstrated a favorable balance between friction and wear, with a wear resistance close to BRO ( K ≈0.8 × 10 ⁻⁵ mm ³ /N m) and a CoF similar to pure PLA ( μ ≈0.28). The paper extensively discusses the wear mechanisms observed on the worn surfaces, as well as the tribofilm formed on the steel disc counterpart.

The growing demand for sustainable, high-performance composite materials has increased the interest in natural fibers as reinforcements for brake friction materials (BFMs). Silk and Grewia optiva fibers, in particular, have emerged as promising candidates for BFMs due to their good mechanical properties, biodegradability, and availability. To evaluate their potential, friction materials were formulated with 6% Grewia (GF), 6% silk (SF), and a hybrid formulation containing 3% of both fibers (SGF), alongside a reference material reinforced with 6% aramid fiber (AF). These composites were then tested on a braking tribometer using an extended SAE J2522 procedure to assess their performance. The AF formulation showed slightly better wear resistance and the GF formulation showed inferior performance during high-temperature cycles, whereas SF and SGF performed close to the reference formulation (AF) in these sections. In terms of friction stability, SF matched the AF formulation, while GF demonstrated significantly poorer stability. The first high-temperature exposure of the BFMs (Fade 1) served as a critical thermal settlement phase, after which they demonstrated both improved friction stability and repeatable performance characteristics. Finally, this study demonstrates that silk fiber represents a viable, sustainable alternative to aramid in BFMs, exhibiting comparable performance in terms of friction stability and thermal resistance.

Global demand for manufacturing processes aligned with cleaner practices has increased interest in vegetable-based oils (biolubricants) as eco-friendly alternatives to petroleum-based oils. In this context, a novel vegetable emulsion was proposed as a cutting fluid in a turning process. This emulsion was formulated with 1 wt% aminolyzed castor oil (ACO) and 99 wt% water. ASTM A182 F55 super duplex stainless steel was selected as the workpiece because of its high work-hardening rate, high ductility, and low thermal conductivity result in low machinability, opening new research opportunities in the field of machining. Three cutting conditions were used in the turning process: dry cutting (DRY), Minimum Quantity Lubrication (MQL) with a semi-synthetic emulsion (SS-MQL), and MQL with an ACO emulsion (V-MQL). The experiments were conducted using TiAlN-coated carbide cutting tools. The results of V-MQL exhibited the lowest tool wear among the cutting conditions due to the formation of a protective film promoted by the ACO emulsion, which was adsorbed on the tool’s surface. Regarding chip formation, the DRY condition produced long and tangled chips with larger saw-tooth spacing. In contrast, both MQL conditions generated shorter chips with smaller saw-tooth spacing due to the cooling effect of the emulsions. Additionally, V-MQL promoted the highest chip work hardening, followed by SS-MQL and DRY. All cutting conditions showed a suitable surface finish, especially V-MQL and SS-MQL. Under the cutting conditions used in this study, the ACO emulsion proved effective for machining ASTM A182 F55 steel, standing out as a promising alternative to conventional cutting fluids.