## 4. Constructional and Functional Aspects of Chains
### Types, Materials, and Applications
Chains made from stainless steel also exhibit high tensile and compressive strength, allowing them to carry heavy loads. This material is widely used in the food, pharmaceutical, and chemical industries, where high hygiene standards and durability are required. However, its higher cost compared to carbon steel, along with slightly lower mechanical performance in some cases, can be limiting factors. Carbon steel, though more susceptible to corrosion, is known for its high tensile strength and wear resistance. It is relatively inexpensive, making it a common choice in heavy industry, mining, and construction. Its limitation lies in its vulnerability to moisture and aggressive chemical environments, which restrict its use in certain applications requiring enhanced resistance. Chrome-nickel steel alloys are also used for chain production due to their fatigue resistance and corrosion resistance. These alloys are suitable for demanding operating conditions, such as those found in the chemical and food processing industries. Alloys made from aluminum, titanium, or bronze offer additional benefits, including lightness, ease of machining, and corrosion resistance, which make them ideal for specialized applications. However, their drawbacks include higher production costs and, in some cases, lower long-term durability compared to steel. In recent years, the importance of plastics and composites in chain production has been increasing. In certain applications\(-\)particularly where weight reduction is critical\(-\)chains made from synthetic materials or composites are used [15]. Materials such as nylon, polyurethane, and carbon fibers offer lightweight construction, corrosion resistance, and minimal maintenance. Plastic chains are especially beneficial in applications where noise reduction, low friction, and energy efficiency are priorities. Carbon fibers and Kevlar are known for their exceptional tensile strength, allowing for reliable performance under dynamic loads [16]. The use of these materials also extends chains' lifespans and reduces energy consumption in transport systems. Modern conveyor chains are increasingly incorporating these materials instead of traditional steel links. This shift results in significantly lighter constructions, directly enhancing energy efficiency. Lightweight chains reduce machine load, leading to energy savings--especially in contexts where speed and precision are essential. Ceramic-matrix chains produced from alumina-zirconia (ZTA/ATZ) composites have lately been demonstrated for high-temperature conveyor systems and still retain?75% of their room temperature Vickers hardness after 1 h at 600 \({}^{\circ}\)C [65; 66; 67]. Hybrid roller chain links that marry quenched-and-tempered steel side-plates with filament-wound carbon fiber pins achieved a two-fold increase in bending/fatigue life in drivetrain simulations relative to all-steel references [68]. Additive-manufactured chains fabricated either by laser powder-bed fusion of 18 Ni-300 maraging steel or by continuous-fiber fused-filament fabrication (CFF) offer 20-30% mass reduction while matching the ultimate tensile strength of conventionally machined links [69; 70]. These emerging material platforms underline how quickly the palette of chain materials is widening and confirm the need for dedicated design-to-failure criteria in future standards. The implementation of composites in place of traditional materials is a step toward lowering raw material consumption and reducing CO2 emissions. Through the adoption of advanced technologies, manufacturers of conveyor chains play an important role in guiding the industrial sector toward sustainable development. The chain industry is experiencing a technological transformation driven by the adoption of modern materials. The overarching goal is to strike a balance between lightness, strength, and durability, which is essential for effective operation under diverse service conditions.