The fundamentals of coating tribology are presented in a generalised holistic approach to friction and wear mechanisms of coated surfaces in dry sliding contacts. This is based on a classification of the tribological contact process into macromechanical, micromechanical, tribochemical contact mechanisms and material transfer. The tribological contact process is dominated by the macromechanical mechanisms, which have been systematically analysed by using four main parameters: the coating-to-substrate hardness relationship, the film thickness, the surface roughnesses and the debris in the contact. The description covers both soft and hard coatings with thicknesses typically in the range 0.1–50 μm, where the interaction between the coating and the substrate is essential to the tribological behaviour. The concept is supported by experimental observations. The important influence of thin tribo- and transfer layers formed during the sliding action is shown. Optimal surface design both regarding friction and wear can be achieved by new multilayer techniques giving reduced stresses, improved adhesion to substrate, more flexible coatings and harder and smoother surfaces. The differences in contact mechanisms in dry, water- and oil lubricated contacts with coated surfaces is illustrated by experimental results from diamond-like coatings sliding against a steel ball. The mechanisms of the formation of dry transfer- and tribolayers and lubricated boundary and reaction films are discussed.

Tribology of thin coatings

Optimal planning of municipal solid waste management systems in an integrated supply chain network

A life cycle assessment (LCA) practitioner is often faced with the problem of missing chemical life cycle inventory (LCI) data sets, as current databases cover only a small fraction of chemicals us...

Comparative Evaluation of Chemical Life Cycle Inventory Generation Methods and Implications for Life Cycle Assessment Results

Polymer nanocomposites with enhanced performances are becoming a trend in the current research field, overcoming the limitations of bulk polymer and meeting the demands of market and society in tribological applications. Polytetrafluoroethylene, poly(ether ether ketone) and ultrahigh molecular weight polyethylene are the most popular polymers in recent research on tribology. Current work comprehensively reviews recent advancements of polymer nanocomposites in tribology. The influence of different types of nanofiller, such as carbon-based nanofiller, silicon-based nanofiller, metal oxide nanofiller and hybrid nanofiller, on the tribological performance of thermoplastic and thermoset nanocomposites is discussed. Since the tribological properties of polymer nanocomposites are not intrinsic but are dependent on sliding conditions, direct comparison between different types of nanofiller or the same nanofiller of different morphologies and structures is not feasible. Friction and wear rate are normalized to indicate relative improvement by different fillers. Emphasis is given to the effect of nanofiller content and surface modification of nanofillers on friction, wear resistance, wear mechanism and transfer film formation of its nanocomposites. Limitations from the previous works are addressed and future research on tribology of polymer nanocomposites is proposed.

Effect of Nanofillers on Tribological Properties of Polymer Nanocomposites: A Review on Recent Development.

Obtaining sustainable production from the product design analysis

Life cycle assessment of a domestic induction hob: electronic boards

Environmental impact analysis of the injection molding process: analysis of the processing of high-density polyethylene parts

During the last decades, society’s concern for the environment has increased. Specific tools like the Life Cycle Assessment (LCA), and software and databases to apply this method have been developed to calculate the environmental burden of products or processes. Calculating the environmental impact of plastic products is relevant as the global plastics production rose to 288 million tons in 2012. Among the different ways of processing plastics, the injection molding process is one of the most used in the industry worldwide. In this paper, a sensitivity analysis of the environmental impact of the injection molding process has been carried out. In order to perform this study, the EcoInvent database inventory for injection molding, and the data from which this database is created, have been studied. Generally, when an LCA of a product is carried out, databases such as EcoInvent, where materials, processes and transports are characterized providing average values, are used to quantify the environmental impact. This approach can be good enough in some cases but in order to assess a specific production process, like injection molding, a further level of detail is needed. This study shows how the final results of environmental impact differ for injection molding when using the PVC’s, PP’s or PET’s data. This aspect suggests the necessity of studying, in a more precise way, this process, to correctly evaluate its environmental burden. This also allows us to identify priority areas and thereby actions to develop a more sustainable way of manufacturing plastics.

https://www.mdpi.com/2071-1050/7/4/3792/pdf

LCI Databases Sensitivity Analysis of the Environmental Impact of the Injection Molding Process

The influence of environmental conditions on the dimensional stability of components injected with PA6 and PA66

Reducing energy consumption is an important issue for green manufacturing. In this paper, the specific energy consumption (SEC) of the injection molding process is analyzed. Results showed significant variations depending on the injected thermoplastic material and the type of injection molding machine (IMM) suggesting that IMM selection has a high relevance for the efficiency, cost and environmental impact of the process. The manufacturing of 36 plastic parts has been characterized by measuring the electricity consumption and obtaining the environmental impact, being this consumption its most important factor. A descending tendency for both is observed when high throughputs are obtained because the size of the IMM is more optimized. Conversely, the savings obtained by the all-electric IMMs are significant. This research could help engineers to properly select an IMM by taking into account the part weight, material and environmental criteria. Also, this study will be useful for life cycle assessment (LCA) practitioners. Real consumption data is presented, providing details about the materials, and relationships with the IMM that was used. The high variability suggests that if the injection molding process is relevant in a LCA study, its consumption must be analyzed in depth, preferably by measuring real consumptions in the factory.

Influence of material and injection molding machine’s selection on the electricity consumption and environmental impact of the injection molding process: An experimental approach

Daniel Elduque

Papers

Life cycle assessment of a domestic induction hob: electronic boards

Environmental impact analysis of the injection molding process: analysis of the processing of high-density polyethylene parts

LCI Databases Sensitivity Analysis of the Environmental Impact of the Injection Molding Process

The influence of environmental conditions on the dimensional stability of components injected with PA6 and PA66

Influence of material and injection molding machine’s selection on the electricity consumption and environmental impact of the injection molding process: An experimental approach