Metalworking Industry Research Articles

Chamfer texturing of tungsten carbide inserts applied to turning of grey cast iron

Owing to the relevance of the turning operation to the metal working industry, intensive research is constantly undertaken in order to improve the quality of manufactured products, optimise production time, and reduce costs. Among the investigated topics, texturing of the cutting tool rake face has received increasing attention since it can affect tool life, process forces, and cutting temperature. The contribution of the present work resides in depicting the procedure for laser texturing the cutting edge chamfer of uncoated tungsten carbide inserts aiming at weakening the stability of the seizure region. Moreover, the performance of textured and non-textured tools was assessed when turning grey cast iron. Two parallel columns of dimples with an average diameter of 40 μm and variable distance between rows of dimples (60, 100, and 200 μm) were produced and the turning experiments were carried out dry and with the application of minimal quantity lubrication (MQL). The findings indicated that the lowest values for the turning force components were obtained when cutting with textured tools possessing dimples 100 μm apart and using MQL. Texturing did not affect tool life in dry turning; however, when cutting with MQL, the longest tool lives were obtained using the tools textured with dimples 60 and 100 μm apart. Finally, machined surface roughness was not affected by tool texturing and decreased slightly with the application of MQL.

Localization models for the plastic response of polycrystalline materials using the material knowledge systems framework

Crystal plasticity finite element simulations provide physics-based predictions of the plastic response in polycrystalline metals subjected to large plastic strains. Despite their demonstrated high fidelity in a number of applications, these approaches have not yet been adopted broadly by the metal working industry because of their extremely high computational cost. This work develops and applies a novel strategy for reduced-order partitioning of the macroscopically applied plastic stretching tensor on a polycrystalline aggregate to regions within individual grains (i.e. localization of the plastic stretching tensor). This new strategy is seen to provide reasonable predictions for the localized plastic stretching tensors at dramatically reduced computational cost. The strategy presented here extends the prior successes of the materials knowledge system (MKS) framework for the localization of the plastic stretching tensor in composites of two isotropic phases to polycrystalline volumes through the use of the generalized spherical harmonics as a Fourier basis for capturing the functional dependence of the localization kernels on the crystal lattice orientation. It is demonstrated that this extension of the MKS framework is capable of providing good predictions for all components of the second-rank local plastic stretching tensor for any given macroscale imposed plastic stretching tensor with about three to four orders of magnitude savings in the computational cost. This work has the potential to open new research avenues for computationally low-cost, fully coupled, multiscale simulations of plastic deformations in polycrystalline metals.

Tribomechanical Behaviour of TiAlN and CrAlN Coatings Deposited onto AISI H11 with Different Pre-Treatments

In the metalworking industry, different processes and applications require the utilisation of custom designed tools. The selection of the appropriated substrate material and its pre-treatment as well as the protective coating are of great importance in the performance and life time of forming tools, dies, punches and coated parts in general. TiAlN and CrAlN coatings have been deposited onto the hot work tool steel AISI H11 by means of Direct Current Magnetron Sputtering. Prior to the deposition, the steel substrate was modified by the implementation of three different pre-treatments: nitriding of the annealed substrate [Nitr.], heat treatment of the steel (quenching and double tempering) [HT] and nitridation subsequent to a heat treatment of the substrate [HT + Nitr.]. The purpose of this research is to obtain valuable information on the microstructural properties and tribomechanical behaviour of two of the most promising ternary transition metal nitride coatings, TiAlN and CrAlN, when deposited on the AISI H11 steel with different initial properties. The different pre-treatments performed to the steel prior to the deposition favour the tailoring during the design and construction of tools for specific applications. The microstructure, the adhesion and the wear resistance of TiAlN coatings were highly influenced by the substrate preparation. Contrarily, CrAlN results were more independent of the substrate preparation and no high influences were found. For instance, the adhesion of the TiAlN coating varied from 17 to 43 N for the coating deposited onto the HT + Nitr. substrate and the HT substrate respectively, while the lowest and highest adhesion of the CrAlN coating varied between 42 and 53 N for the HT and the HT + Nitr. respectively. Likewise, the wear coefficient of the CrAlN were ten times smaller than those found for the TiAlN coatings, presumably due to the presence of hex-AlN phases and the small differences on the Young´s Modulus of the substrate and the CrAlN coatings.

Early Effect Markers and Exposure Determinants of Metalworking Fluids Among Metal Industry Workers: Protocol for a Field Study.

BackgroundExposure to aerosols from metalworking fluids (MWF) has previously been related to a series of adverse health outcomes (eg, cancer, respiratory diseases). Our present epidemiological study focuses on occupational exposures to MWF and a panel of exposure and effect biomarkers. We hypothesize that these health outcomes are caused by particle exposure that generates oxidative stress, leading to airway inflammation and ultimately to chronic respiratory diseases. We aimed to assess whether MWF exposure, in particular as characterized by its oxidative potential, is associated with biomarkers of oxidative stress and inflammation as well as genotoxic effects.ObjectiveThe ultimate goal is to develop exposure reduction strategies based on exposure determinants that best predict MWF-related health outcomes. The following relationships will be explored: (1) exposure determinants and measured exposure; (2) occupational exposure and preclinical and clinical effect markers; (3) exposure biomarkers and biomarkers of effect in both exhaled breath condensate and urine; and (4) biomarkers of effect, genotoxic effects and respiratory symptoms.MethodsAt least 90 workers from France and Switzerland (30 controls, 30 exposed to straight MWF and 30 to aqueous MWF) were followed over three consecutive days after a nonexposed period of at least two days. The exposure assessment is based on MWF, metal, aldehyde, and ultrafine particle number concentrations, as well as the intrinsic oxidative potential of aerosols. Furthermore, exposure biomarkers such as metals, metabolites of polycyclic aromatic hydrocarbons and nitrosamine are measured in exhaled breath condensate and urine. Oxidative stress biomarkers (malondialdehyde, 8-isoprostane, 8-hydroxy-2’-deoxyguanosine, nitrates, and nitrites) and exhaled nitric oxide, an airway inflammation marker, are repeatedly measured in exhaled breath condensate and urine. Genotoxic effects are assessed using the buccal micronucleus cytome assay. The statistical analyses will include modelling exposure as a function of exposure determinants, modelling the evolution of the biomarkers of exposure and effect as a function of the measured exposure, and modelling respiratory symptoms and genotoxic effects as a function of the assessed long-term exposure.ResultsData collection, which occurred from January 2018 until June 2019, included 20 companies. At the date of writing, the study included 100 subjects and 29 nonoccupationally exposed controls.ConclusionsThis study is unique as it comprises human biological samples, questionnaires, and MWF exposure measurement. The biomarkers collected in our study are all noninvasive and are useful in monitoring MWF exposed workers. The aim is to develop preventative strategies based on exposure determinants related to health outcomes.International Registered Report Identifier (IRRID)DERR1-10.2196/13744

Surface structuring of polycrystalline diamond (PCD) using ultrashort pulse laser and the study of force conditions

In the metal working industry, cutting tools for high precision application are usually made from non-conventional super hard materials, for example, diamond (D) and cubic boron nitride (CBN). These materials are composites of geometrically undefined grains embedded in metallic binder. For some special applications, these tools are constructed from one or several cutting edges and guide rails. Typical examples are honing and guided reaming tools for the fine machining of bores. These tools improve the form, dimension and surface quality, as well as the geometrical tolerances of the machined workpieces. The guide rails of the tool play an important role as they usually support the tool shaft in the rotating movement, for example the guiding stones of the honing tool. In the case of dynamic contact, higher demands on material properties such as hardness and wear resistance are necessary. In this study, a polycrystalline diamond (PCD) grade is employed as a new material for guide rails. Contacting surfaces of the PCD guide rails are textured with three defined patterns by a femtosecond laser setup. It is aimed to improve the force conditions by means of changing the contacting conditions. Within this regard, the tribological properties of the three patterns on PCD rails are characterized using a nanotribometer and compared to the conventional guide rails made of cemented tungsten carbides. A force simulation based on the honing processes is built up and conducted to predict the force conditions of each different pattern. At the same time, morphological modification, assessment of surface and microstructural integrity of the structured PCD guide rails are also studied in this work.

Industrial safety and health actions for business growth in a metalworking industry

Objectives. Improve the working conditions and productivity index through the implementation of Industrial Safety and Hygiene and Plant Distribution actions in a pressure foundry company. Methodology. 1. Analysis of the manufacturing process of aluminum and zamak parts. 2. To identify the risk elements those do not allow to work in a safe and a right way. 3. To assign safety equipment according to the risks of the area and the integration of a Joint Commission on Safety and Industrial Hygiene. 4. To identify the containers for waste management in the different phases of the process. 5. To re-distribute the lay out to improve ventilation and lighting of the areas. 6. To analyze the results, considering the impact on the improvement of the company's productivity. Contribution. Ensure the safety of its employees, achieve a better work environment, comply with established regulations and improve productivity in the company.

The analysis of physical and chemical efficiency of electroflotation process the removing products of hydrolysis titanium tetrachloride from technogenic effluents

The physicochemical efficiency of the electroflotation process for the extraction of TiCl4 hydrolysis products from aqueous electrolyte solutions was studied. They simulate the compositions of typical industrial wastes of metallurgical and metal-working industries that contain colloid-resistant compositions of titanium tetrachloride hydrolysis products, its oxides and hydroxides. The effect of various surfactants of anionic, cationic and non-ionic nature in a wide pH range (2-12) on the efficiency of electroflotation processes of extraction, separation and concentration of dispersed titanium (IV) compounds has been studied. It has been established that the electroflotation process of the extraction of hydrolysis products of TiCl4 proceeds quite effectively with a maximum degree of extraction of 98-99% (in the acidic region at pH = 3, in alkaline at pH = 8).

Differences in work injury risk between immigrants and natives: changes since the economic recession in Italy

BackgroundIt is known that occupational injury rates are higher for immigrant than for native workers, however the effects of the economic cycles on these differences has not been assessed to date. The aim of the paper is to test if the crisis has the same mechanism of selection in the two groups by comparing injury rates in 2005 (before the crisis) and in 2010 (after the crisis).MethodsThe Work History Italian Panel-Salute integrated database was interrogated to identify employment contracts in the metalworking and construction industries for the years 2005 and 2010 and the occupational injuries. A definition based on the type of injury, less likely to be biased by underreporting, was used to select serious events. Immigrants and natives were matched using the propensity score method and injury rates were calculated in the two years. Analyses were stratified by industry.ResultsIn the metalworking industry injury rates slightly increased over time for both groups, and were higher among immigrant than native workers in both 2005 and 2010. In the construction industry the 2005 injury rate was the same in the two groups, and there was a negative trend over time in both groups. However the decline in the 2010 injury rate for Italian workers was much larger, which led to a considerable increase of the incidence rate ratio of immigrants with respect to native (IRR 3.83, 95% CI 2.52–5.75).ConclusionsThe economic recession had an impact on the risk of workplace injury. Though the main observed factors (18 variables) usually reported in literature to explain the higher injury rates of the immigrant workers were controlled through the matching, there were still differences between immigrants and natives. The main reason is that immigrants continue to be assigned to the more dangerous jobs and the more dangerous tasks within these job. Furthermore, also differences in the perception of workplace injury risks, linguistic barriers, and cultural factors may have a role in explaining this gap.

Influence of artificial aging on the lubricating ability of water miscible metalworking fluids

The understanding of the complex aging processes of water miscible metalworking fluids and their effect on the performance in machining processes is of high relevance for the metalworking industry. Nevertheless, only little knowledge is available in this context. Due to the highly dynamic interactions in the complex ecosystem “metalworking fluid”, a distinct correlating of the aging process with the performance of the fluid in metalworking processes is hardly possible. Consequences of the aging process on physical, chemical and biological properties of the fluid have been described in several research works. These consequences comprise aspects such as the decrease of the pH-value, the increase of the droplet size, the presence of bacterial cells or the modification of the metalworking fluid composition. The novel approach of the presented work aims to investigate the individual influence of isolated aging aspects on the lubricity of metalworking fluids. Therefore, selected aging aspects were artificially varied separately from each other and evaluated in tribological experiments. It could be shown that the physical presence of bacterial cells as well as extracellular polymeric substances have positive influence on the lubricating ability while the pH-value has no effect and the droplet size only a slight influence on the fluids performance. The results reveal essential knowledge for the design of future monitoring and maintenance strategies for water miscible metalworking fluids.

Labor Productivity During the Great Depression in UK Manufacturing

This paper provides estimates of labor productivity for one-third of UK manufacturing during the Great Depression. It covers engineering and allied industries, and metal working industries. A unique data set of actual hours of work is combined with comparable real output and employment statistics. It establishes that output per worker-hour was countercyclical in the 1929-1932 peak-to-trough years of the Depression. This result has also been found for US manufacturing over the same period. Working time is found to play a crucial role the UK productivity response. Countercyclical productivity is discussed in terms of (i) the strong final output and consumer price deflations of 1929 to 1934, (ii) an absence of significant labor hoarding, and (c) diminishing returns to long weekly hours of work.

Use of Metal-mechanics Waste as an Addition in the Production of an Ecological Concrete

Currently, buildings are on the rise, which causes significant environmental pollution due to the lack of controlled landfills to deposit solid construction wast; an alternative solution is to recycle this waste produced by the construction and or demolition of concrete elements structural, and use them as coarse aggregate in the manufacture of concrete. On the other hand, the metalworking industry uses iron and steel as primary inputs, which are the main components of industrial waste, with its generation sources being industrial plants and manufacturing workshops for small and medium enterprises; a solution to this problem is to use your waste as a fine aggregate in the production of concrete due to its good properties. These solution alternatives preserve natural resources and promote their sustainability. The research work developed focuses on the use of structural concrete and steel waste to reduce its amount of waste and it is proposed to add it to the concrete. The results show that the addition of steel chips in concrete compared to standard concrete results in reduced slump, increased unit weight and contributes to the improvement of compressive strength, tcylinder splitting tensile strength and flexural strength.

Evaluation of proceedings for SMEs to conduct I4.0 projects

For the digital transformation of their business, companies conduct specific change projects. In comparison to large companies, small and medium-sized enterprises (SME) have specific constraints, e.g. limited resources. Many proceedings are now available to support SMEs in their transformation process towards industry 4.0 (I4.0). The current scientific state of affairs is presented by a literature review and the publications are evaluated in their applicability for SMEs. The work was carried out in the research project OBerA, which aims to support companies in the metalworking industry in the digitalization of their system landscape. The project consortium consists out of five SME companies from the region of Franconia in Bavaria and Siemens as technology partner. It is carried out that existing proceedings still have drawbacks and further researchwork is needed.

Development of a mathematical model of heat-treating furnaces with sole flues and a numerical study of its operation parameters

The main element of metalworking, engineering and other industries is heating and heat-treating furnaces. An array of workpieces that are loaded into the furnace includes bulk tanks with different parameters. The existing designs of heating furnaces have a number of disadvantages, one of which is the lack of heat carrier filtration in the vertical direction. However, this feature can be found in the developed design of the batch furnace with sole flues. The aim of the work is to develop and study the parameters of a mathematical model of the heating process of a bulk tank in a heat-treating furnace with sole flues. The paper describes and studies a mathematical model of a heat-treating furnace equipped with special sole flues. The bulk tank model is built based on a fractal structure, in particular the Menger sponge. To solve the problem of deter-mining the temperature field of the bulk tank, we used a numerical calculation of heat exchange based on the finite-difference method, also called the grid method. For this purpose, a new design of the batch furnace with hearth chambers has been proposed. As a result of mathematical modeling of the heating process, we have obtained a graph reflecting the temperature field of the bulk tank on the surface and in the heating center. We have also compared the temperature regime of bulk tank heating under normal conditions and in conditions of additional heat carrier filtration through the flues from the hearth chambers to the furnace hearth. The reliability of the results is confirmed by comparing the numerical simulation results and the results of the physical experiment. The error is not more than 10 %. The efficiency of the heat-treating furnace is improved by additional heat carrier filtration through special channels in the furnace sole. The obtained mathematical model can be used to calculate different heating modes in heat-treating furnaces and to develop technological maps of heating bulk tanks with different porosity values.

Improving the Machining Process of the Metalworking Industry Using the Lean Tool SMED

The project here presented was developed in a metalworking company, where several areas requiring improvement were identified. The study addresses the elimination of waste and increase of productivity in the machining sector of the company. To this purpose key processes were identified and mapped using flowcharts and VSM (Value Stream Mapping). Achieved improvements involved decreasing setup times by resorting to the lean tool SMED (Single Minute Exchange of Die). Setup times were reduced in 40% on the vertical milling machine of the company, and in 57% on the horizontal milling machine.

Gradient Boosted Trees Predictive Models for Surface Roughness in High‐Speed Milling in the Steel and Aluminum Metalworking Industry

High‐speed machining is a technique that maintains a high interest in the manufacture of metal parts for the excellent results it provides, both in surface finish and in economic benefits. In the industry, the tendency is to incorporate data management and analysis techniques to generate information that helps improve the surface roughness results in machining. A good alternative to improve the surface quality results in the manufacture of metal parts is using predictive models of the surface roughness. In this document, we present work done with experimental data obtained from two high‐speed machining (HSM) machines with different types of tools and cutting conditions, conducted under an experimental design with interest in three of factors commonly studied to generate surface roughness models: tool characteristics, cutting conditions, and characteristics of the machined material. Steel and aluminum alloys were used in the experimentation. The results are contrasted with prior experiences that use the same experimental design but with different soft computing techniques and they are also contrasted with the results of similar previous works. Our results show accuracies ranging from 61.54% to 88.51% on the datasets, which are competitive results when compared with the other approaches. We also find the axial cut‐depth is the most influential feature for the slots datasets and the hardness and diameter of the cutting tool are the most influential features for the geometries datasets.

Improving the Machining Process of the Metalwork Industry by Upgrading Operative Sequences, Standard Manufacturing Times and Production Procedure Changes

Manufacturing industries are currently experiencing important changes towards digitization and autonomous production control, which is known as Industry 4.0. However, the profitability of some companies, namely Small and Medium Enterprises (SMEs), and of some industrial sectors does not allow for great investments, meaning that is necessary to undertake simple changes that potentially can lead to significant gains. This is the case for the metalwork company under study, where wastes related to the large parts movement and non-conformities detected before and after the parts delivered to the customers have been identified. The elimination of these wastes can contribute to a significant increase in the profitability of the company. The use and integration of several Lean tools made it possible to achieve this goal for this company. Amongst other improvements on productivity and waste reducing, a 59% reduction in the time required to move parts of up to 1000 kg, a reduction of 2.04% on the external non-conformities (i.e. on non-conformities detected outside the company) and 3.99% on the internal non-conformities, was achieved.

Influencia de las TIC en la competitividad en las Mypes del sector metalmecánico de Paucarpata, 2018.

Este trabajo muestra los resultados de una investigación que se ha realizado en el distrito de Paucarpata para medir el nivel de impacto de la utilización de las Tecnologías de Información y Comunicación (TIC) en la competitividad de la micro y pequeñas empresas del sector metalmecánica, y se encuestado a 50 directivos de empresas seleccionadas aleatoriamente sobre el uso o disponibilidad de 10 herramientas TIC y sobre el crecimiento en el mercado, desempeño empresarial, rentabilidad y relaciones humanas. Los resultados muestran que el nivel de uso de TIC en las Mypes de metalmecánica es bajo, y las correlaciones con las dimensiones de la competitividad, salvo en los procesos productivos, muestran que existe un alto grado de impacto. Estos resultados contribuyen al conocimiento sobre la situación de uso de TIC y su impacto en la competitividad de las Mypes del sector metalmecánico, y permiten confirmar la importancia de impulsar programas de fomento de uso de TIC, desarrollados por unidades gubernamentales o privadas, como factor relevante para elevar los niveles de competitividad.

Interdisciplinary and multiprofessional outpatient secondary individual prevention of work-related skin diseases in the metalworking industry: 1-year follow-up of a patient cohort

BackgroundIn Germany, work-related skin diseases are predominant within the spectrum of reported occupational diseases. Metal workers are among the high-risk professions. Offering effective prevention programs to affected patients is of utmost importance to avoid deterioration of the disease and job loss. We conducted a 1-year follow-up in patients who participated in a multidisciplinary, complex outpatient prevention program representing a standard procedure of patient care by the respective statutory accident insurance.MethodsThe multi-component prevention program consists of multiprofessional individual patient counseling, a structured skin protection seminar in a group, as well as workplace visits and on-site counseling in terms of appropriate skin protection (e.g. gloves). An observational study with a 1-year follow-up and four measurements (T1-T4, longitudinal pre/post-test design) including dermatological examinations and standardized written questionnaires was conducted between 2013 and 2016 to assess changes over time regarding job loss and disease severity.ResultsData from 94 patients (87 male, mean age: 45.4 years) were included in the analysis. One year after the skin protection seminar (T4), 83 patients (88.3%) remained in their original professional metalworking activity and four patients (4.3%) had given up their profession because of their skin disease. At baseline (T1), irritant contact dermatitis of the hands was the most frequent diagnosis (80.7%). Methods for self-reported disease severity showed good correlation with the clinical gold standard at T1 and T2 (dermatological examination with the Osnabrück Hand Eczema Severity Index / OHSI), and a significant decrease of the self-reported disease severity was found over time from T1 to T4 (p < 0.001). Further results indicate an improved self-perceived disease control and an overall satisfaction with the prevention program.ConclusionsThe results of this observational study demonstrate that the comprehensive prevention program positively influences the course of work-related skin diseases, increases the possibility to continue working in a “high-risk” profession and improves the disease management of metal workers. In the long term, the prevention program may lead to cost savings by preventing high therapy costs or professional retraining.

Solving the two-dimensional knapsack problem considering cutting-time and emission of particulate matter in the metalworking industry

Abstract— This article presents a metaheuristic to solve the two-dimensional knapsack problem on applications of metalworking industries. The proposed algorithm is based on a GRASP procedure and its performance is assessed through comparison of the solutions computed for the knapsack problem. We have used two references for comparison: instances reported in the literature and experimental data obtained with two variations on the cutting method. The first reference allows us to conclude about the used area and the computational time. The second reference let us to explore the performance of the solutions with respect to the cutting-time and the amount of particles emitted. The methodology is composed by four steps: (1) selection of the instances, (2) design and implementation of the algorithms for optimization and post-optimization, (3) computing of the solutions and registering of cutting-times and particles emitted for each solution and (4) performance validation through comparison of solutions. The results permit to conclude a good behavior of the proposed algorithm reaching the performance reported in some instances and improving others. Additionally, the algorithm exhibits a stable computational time even for large-scale instances. It is emphasized that the post-optimization stage reduces the cutting-times without incrementing the emission of particulate matter. As future work we propose: to include a vision system to close the cutting loop; to consider partial damages on the plate; and to contemplate an exact approach for the sequencing cutting problem.

Skin Permeation of Solutes from Metalworking Fluids to Build Prediction Models and Test A Partition Theory.

Permeation of chemical solutes through skin can create major health issues. Using the membrane-coated fiber (MCF) as a solid phase membrane extraction (SPME) approach to simulate skin permeation, we obtained partition coefficients for 37 solutes under 90 treatment combinations that could broadly represent formulations that could be associated with occupational skin exposure. These formulations were designed to mimic fluids in the metalworking process, and they are defined in this manuscript using: one of mineral oil, polyethylene glycol-200, soluble oil, synthetic oil, or semi-synthetic oil; at a concentration of 0.05 or 0.5 or 5 percent; with solute concentration of 0.01, 0.05, 0.1, 0.5, 1, or 5 ppm. A single linear free-energy relationship (LFER) model was shown to be inadequate, but extensions that account for experimental conditions provide important improvements in estimating solute partitioning from selected formulations into the MCF. The benefit of the Expanded Nested-Solute-Concentration LFER model over the Expanded Crossed-Factors LFER model is only revealed through a careful leave-one-solute-out cross-validation that properly addresses the existence of replicates to avoid an overly optimistic view of predictive power. Finally, the partition theory that accompanies the MCF approach is thoroughly tested and found to not be supported under complex experimental settings that mimic occupational exposure in the metalworking industry.