The components’ lightweighting has been pursued, especially in the transport industry, for greenhouse gas reduction. Topology optimization, being able to allocate the material within a provided design space, is a mathematical method that can support the design of lightweight components, preserving, at the same time, their mechanical performances. In this paper, a standard shape of a component, specifically an automotive bracket, was topology optimized by estimating the impacts of the new designs from an eco-friendly point of view. A subtractive, an additive and a casting manufacturing process were considered as possible manufacturing routes achieving an optimized geometry of the component for each of them. The topology optimizations were performed considering each processes’ peculiarities, introduced as constraints. Same strength for a given set of loads and boundary conditions was the target of each analysis. The component’s lightening can be considered environmentally friendly just after assessing the impacts associated with all the stages of the product’ life cycle. Indeed, each phase of the product’ life cycle can be affected, differently, by the performed topology optimization taking into account the peculiarities of the employed manufacturing process. The overall considerations on the most environmentally safe strategies can, therefore, change according to the specificities of the optimized shapes. The topology optimization showed its utmost potentiality, from a sustainable point of view, if applied to additive manufacturing techniques for the advantages arisen by the capability to manufacture complex shapes benefiting also of reduction time process owing to less material to be deposited.

Gears remain a fundamental component in mechanical power transmission, with ongoing research focused on enhancing performance and sustainability. This study addresses the process of gear lightweighting, a key factor for efficiency improvements in automotive and aerospace sectors. Traditionally, material removal from gear bodies results in weight reduction, but at the cost of increased noise and vibration. A novel approach using hybrid gears, which combine a metal rim and hub with a composite material web, offers a promising solution. This research proposes a comparative environmental analysis among a conventional full steel, a lightweight and a hybrid gear using a life cycle energy quantification. The study considers two End-of-Life (EoL) scenarios: a conventional open loop scenario with partial recycling and a closed loop scenario with comprehensive recycling, including a thermal recycling for carbon fiber-reinforced plastics. The Cumulative Energy Demand (CED) has been conducted by applying a cradle-to-grave approach. The CED has been evaluated for each gear configuration quantifying the impact of each unit process involved in the production of the gear, from raw material extraction to product manufacturing and from use phase to different EoL scenarios. The cumulative results, performed preserving the same mechanical performance, indicate that the CED of the hybrid gear in the conventional open loop scenario is comparable to the one of the full gears, with an increase of 12.58%. In contrast, in the closed loop scenario, the hybrid gear exhibits substantial energy recovery benefits, with an overall CED difference of 7.50% compared to the lightweight gear and of 28.82% compared to the full gear. These results underline the potential of hybrid gears to improve efficiency, being able to achieve a 20% weight reduction with respect to the full gears, and to reduce environmental impact if effective recycling strategies were implemented.

AISI 304 is widely regarded as the most common austenitic stainless steel and is utilized in various household and industrial applications, including food handling equipment, machinery components, and heat exchangers. Its popularity stems from its excellent mechanical properties, corrosion resistance, and ease of manufacturing. Given its diverse applications, it is crucial to study the microstructural evolution and mechanical properties of the welded zone, especially considering the potential for weld decay during fusion welding. In this context, two critical thermal-dependent factors for ensuring high-quality welds are grain growth and hardness variation in the heat-affected zone (HAZ) during the welding process. This paper presents an innovative finite element (FE) model developed to analyze the grain growth and hardness reduction that occur in the HAZ during plasma arc welding (PAW) of AISI 304 steel for solid expansion tube (SET) technology. Using the commercial FE software SFTC DEFORM-3D™, a user subroutine was created that integrates a physics-based model with the Hall–Petch (H-P) equation to predict changes in grain size and hardness. This study introduces a comprehensive numerical model, encompassing the user subroutine, heat source fitting, and geometry, which accurately predicts the thermal phenomena associated with grain coarsening and hardness reduction in the HAZ during the welding of austenitic stainless steel. The results from the numerical model, including the customized user routines, show good agreement with experimental data, leading to a maximum error prediction of 10 HV in hardness, 30 µm in grain size, and 10% in HAZ extension.

The growing demand for high-performance, sustainable micro-moulded components requires integrated approaches to material and process selection. The study presents a Life Cycle Engineering (LCE) framework for the integrated selection of materials and manufacturing technologies for micro-injection molds, combining Life Cycle Assessment (LCA), Life Cycle Costing (LCC), and multi-criteria decision models. The methodology implements multicriteria cost impact maps and ternary LCA–LCC–technical performance model, allowing for result normalization and sensitivity analysis with respect to criterion weighting. The framework is applied to molds fabricated from steel, aluminium alloy, polyether-ether-ketone (PEEK), and high-temperature resin, using both subtractive and additive processes, with topological optimization. Mass reductions of up to 22% achieved through optimization translate into cost and environmental impact savings of 30–45% during production and use phases, although with potential service life reductions of up to 50% for polymeric materials. LCA and LCC analyses highlight production and use as the dominant life cycle phases, with end-of-life (EoL) impacts being comparatively minor. Sensitivity analysis shows that: (i) cost-prioritized scenarios select optimized steel molds; (ii) scenarios prioritizing lightweight design and environmental performance select advanced polymers and additive manufacturing; (iii) balanced scenarios identify PEEK as the optimal solution. The proposed framework enables the concurrent selection of material and technology aligned with design objectives and geometric optimization, providing quali-quantitative support for sustainability-oriented industrial decision-making across the life cycle.

Finned tubes improve the efficiency of air-cooled heat exchangers by increasing the transmission surface area. The rolling-extrusion process can be employed in their manufacturing by plastic deforming single- or multi-material tubes. The forming steps are usually performed by rotating specific heads composed of a series of disks, whose dimensions are customized to achieve the desired fins’ sizes in terms of height, thickness and pitch. Process parameters, such as the temperature of the disks and the processed material or the lubricant conditions mainly affect the quality of the obtained products in terms of performance, but also in terms of integrity of both manufactured parts and employed equipment. The rolling-extrusion was analysed by a two-dimensional finite-element model to detect stress and strain distributions due to the forming phases. The numerical model focuses on bimetallic finned tubes utilizing an axisymmetric tube geometry with a Norton–Hoff viscoplastic material model. The executed simulations were set to accurately predict the fin shapes using as reference experimental evidence. Effects of specific process variables, including disk temperature, tube preheating and lubrication conditions were monitored. The results highlighted how changes in both disk and tube temperatures and lubrication conditions influence the risk of defects, including fin ruptures, pitch irregularities and tool failures. Specifically, tube preheating increased disk temperatures and minimized friction conditions reducing stresses and deflections in the critical zones. The results offer practical guidelines to improve product quality and production efficiency in industrial settings.