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In addressing the issues of laser defocusing, laser beam interference, and low melting efficiency prevalent in current gear laser cladding path planning, a method for gear laser cladding path planning is formulated based on area segmentation and trajectory refinement. Firstly, the tooth surface model is reconstructed using three times NURBS surfaces. Subsequently, the tooth failure region is extracted through point cloud data alignment and Boolean operations, and the laser scanning region is preliminarily delineated using a graphical convolutional neural network. This is further refined by employing an ant colony algorithm. Secondly, by employing a geometrically constrained mathematical model of the gear, the compensation distance for laser focusing and the feasible domain range of the laser beam are determined to effectuate the trajectory refinement for the gear's laser cladding. Finally, completing the laser scanning area division and trajectory correction to perform the laser cladding gear repair experiment, the experiment relies on the HLC40 laser powder feeding additive manufacturing workstation, adopting the YLR-4000IPG laser for cladding operation. The experimental results demonstrate the absence of focus offset and laser beam interference during the cladding process. Moreover, the total travel distance of the planned path was reduced by 9–12%, the cladding time was reduced by 8–16%, and the morphological quality of the cladding layer was improved by 39–46%. [ABSTRACT FROM AUTHOR]

The research aims to use the latest technology, namely "Concurrent Engineering ", to redraw production and assembly lines to be more efficient and take less time in manufacturing and delivery. Which will help to earn more money, reduce the cost, achieve quality standards, and continue the production line in the assembly lines of the General Company for Mechanical Industries / Automotive Assembly Line, calculating the workstations and stages until the final production and presenting it to the customer. It was noted that there were multiple problems that led to losses on the assembly line as a result of the lack of distribution and timing of activities across the stages of the production line, causing bottlenecks in some workstations. This was reflected in a loss of about (398) minutes at a cost of about $3,900 per minute, which led to insufficient use of human or material resources (machinery and equipment). The current study presented a proposal through which the assembly line can be restructured and the implementation of some activities that are close in completion time can be synchronized, which in turn leads to reducing the total completion time from (937.5 to 772 minutes), that is, by 16.75%, in addition to maximizing working times and machine operating efficiency. And reduce wasted time at most stations. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this article is to present the essence of ergonomics in the position of an assembler in a manufacturing company. Ergonomics is often marginalized in enterprises and its great impact on employee productivity and task satisfaction is overlooked. The purpose of the study was to analyze working conditions and propose ergonomic solutions. Physical strain, mental strain, environmental working conditions and the monotony found at the workplace were analyzed in detail. Design/methodology/approach: All ten employees of the assembly department were surveyed. It should be emphasized that before any changes were implemented, the assemblers' material work environment, working conditions and task loads during the work shift were examined. The following research methods were used: Participatory observation, OWAS method, Chronometry, Lehmann chronometric-tabulation method. Findings: According to production records, before the introduction of ergonomic recommendations, an average of 748 pieces were made at the surveyed workstations during one shift. One month after the introduction of ergonomic solutions, the daily norms were re-examined and on average the number of products made, during one work shift, increased by 3%, or about 22 pieces. Ergonomics also positively affects the company's bottom line. Research limitations/implications: The implementation of ergonomic research is very time consuming. Observation of employees, making chronometry, analysis of the material environment. All this makes the execution of such a research project take a very long time. Practical implications: All the economic benefits that any company can see through the implementation of ergonomic solutions, undoubtedly the strengths of these measures are the improvement of employee safety, the reduction of workplace accidents, the minimization of health ailments associated with improper working conditions, increased job satisfaction, less work fatigue, and the reduction of the uniformity of the work process. Social implications: It is extremely necessary in order to make appropriate modifications to workstations based on the data obtained. After all, this will ensure that employees work safely, efficiently and with the least possible biological cost. Originality/value: A new element for sure is to look at the essence of ergonomics in manufacturing companies. [ABSTRACT FROM AUTHOR]

Many industrial production lines today are initially constructed and outfitted with machinery that, despite its inherent capabilities, struggles to satisfy increasing demand over time. The goal of this research is to find solutions to bottlenecks and improve the efficiency of the production line to satisfy rising productivity demands. The study primarily looks at an existing bottle production line in the edible oil industry, where the product is witnessing a boom in demand. Data on processing times at various workstations and their capacities were thoroughly collected and analyzed. Simulation emerged as the preferred tool for investigating and addressing the production line's intrinsic difficulties. Using Microsoft Excel for statistical analysis, an existing simulation model was created using Flexsim simulation, a process-oriented simulation software, to detect bottlenecks in the production line using the Processor block in the simulation. As a result, a modified model was offered to reduce waiting times by 12%, increase productivity by 6%, and increase overall profitability while efficiently dealing with rising demand across all seasons. As a result, this research represents a complete effort to identify operational challenges and present viable solutions that correspond with the industry's changing objectives. The study aims to contribute to optimizing production lines by utilizing contemporary simulation tools and statistical analysis, guaranteeing that they stay adaptive and responsive in the face of rising productivity demands. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is twofold: first, a case study on applying lean principles in manufacturing operations to redesign and optimize an electronic device assembly process and its impact on performance and second, introducing cardboard prototyping as a Kaizen tool offering a novel approach to testing and simulating improvement scenarios. Design/methodology/approach: The study employs value stream mapping, root cause analysis, and brainstorming tools to identify root causes of poor performance, followed by deploying a Kaizen event to redesign and optimize an electronic device assembly process. Using physical models, bottlenecks and opportunities for improvement were identified by the Kaizen approach at the workstations and assembly lines, enabling the testing of various scenarios and ideas. Changes in lead times, throughput, work in process inventory and assembly performance were analyzed and documented. Findings: Pre- and post-improvement measures are provided to demonstrate the impact of the Kaizen event on the performance of the assembly cell. The study reveals that implementing lean tools and techniques reduced costs and increased throughput by reducing assembly cycle times, manufacturing lead time, space utilization, labor overtime and work-in-process inventory requirements. Originality/value: This paper adds a new dimension to applying the Kaizen methodology in manufacturing processes by introducing cardboard prototyping, which offers a novel way of testing and simulating different scenarios for improvement. The paper describes the process implementation in detail, including the techniques and data utilized to improve the process. [ABSTRACT FROM AUTHOR]

Copyright of Brazilian Journal of Production Engineering / Revista Brasileira de Engenharia de Produção is the property of Brazilian Journal of Production Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Nowadays, the growing interest in industry for enhancing manufacturing processes sustainability is a major trend. One of the most supported strategies to increase the energy-efficiency of manufacturing activities is the control of machine state towards the optimum trade-off between production rate and energy demand. This method is referred to as energy-efficient control and it triggers machines in a standby state with low power request. In this article, multi-stage production lines composed of identical parallel machine workstations are the systems of interest, and the energy-efficient control policies make use of buffer level information. Each machine can be switched off instantaneously and switched on with a stochastic startup time. Problem objective is to minimize the energy demand while ensuring production constraints. This article proposes a novel approach to solve the problem at hand. An exact model for two-stage system is formulated using a Markov Decision Process to be solved with a linear programming methodology. A novel technique, namely the Backward-Recursive approach, is used to address systems with more than two stages. Numerical experiments confirm the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]

The supply of parts to the workstations of assembly lines is a critical design and operational issue. Even though automation and collaborative robots are increasingly used in industry, human operators are frequently employed in the picking and assembly of manual parts. These are time-consuming activities required to be efficiently performed at a high rate and for prolonged periods. Therefore, ergonomic analysis is necessary to reduce the risk of work-related musculoskeletal injuries due to the biomechanical loads. The proper layout of shelves storing part containers along the production line, and the location of the containers on the shelves, may improve picking efficiency and reduce biomechanical risk. Several manufacturing companies use computer-aided ergonomic tools to improve the design of manual production lines, racking, shelving, and workstations. This paper describes the development of a support tool to configure industrial light shelves for feeding the assembly lines. The approach includes the development of a knowledge base to support the geometrical configuration of the shelving and an ergonomic analysis based on the RULA method, considering the shelf's position and the operator's postures. As a test case, the model has been used to evaluate the ergonomic score of some configured shelving based on a prescribed picking sequence. The results show that the proposed approach can help in comparing the ergonomic score of candidate shelving layouts to improve the design of parts storage systems to reduce operators' workload and ergonomic risk. [ABSTRACT FROM AUTHOR]

This study aims to analyze the physiological workload in the virgin coconut oil production process based on energy expenditure evaluations and determine rest periods to ensure that work does not require excessive energy. Assessment of workload objectively using pulse indicators and energy consumption (energy cost) observations at the four stages of the virgin coconut oil production process, namely the process of stripping the coconut husk, the process of cutting the coconut shell, the process of grating the coconut and the process of cooking the coconut milk. The energy expenditure of workers in the coconut coir stripping section is 5,138 kcal/min, the coconut shell cutting section is 2,552 kcal/min, the coconut meat grating section is 3,575 kcal/min, and the coconut milk cooking section is 2,885 kcal/min. Hence the coco coir stripping workstation is included in the heavy workload category with an average cardiovascular load value of %CVL of 56%, which means that the work needs to be improved; the recommended work-rest cycle for workers at the coco peeling workstation is 47 minutes. The workstation for cutting coconut shells to cooking coconut milk is included in the category of moderate workload with a value of %CVL ≤33%, still within the recommended workload limit. [ABSTRACT FROM AUTHOR]

Every company is required to enhance its quality by implementing improvement actions within the company's production system. PT MHE Demag Surabaya is a company engaged in crane girder manufacturing. This research aims to determine the optimal line balancing using the HelgessonBirnie/Ranked Positional Weight (RPW) method, the Largest Candidate Rule method, and the J-Wagon method. Line balancing is necessary due to excess operating time in the crane girder manufacturing workstations, which increases the risk of accidents for the workers. The results of data processing which employed these three heuristic methods demonstrate that the RPW method is the most efficient. The Helgesson-Birnie/Ranked Positional Weight (RPW) method yields the most optimal output, with a line efficiency of 96.67%, balanced delay of 3.33%, and total idle time of 4936.8 seconds using 15 workstations. By utilizing the heuristic methods for line balancing, the efficiency decreases to 144.76%, the balanced delay increases to 14.76%, and the total idle time increases to 86,400 seconds. [ABSTRACT FROM AUTHOR]

This paper introduces the mechanical design and control system of a mobile robot for logistics transportation in manufacturing workshops. The robot is divided into a moving part and a grasping part. The moving part adopts the mecanum wheel four-wheel-drive chassis, which has omnidirectional moving ability. The mechanical system is based on four mechanical wheels, and a modular suspension mechanism is designed. The grasping part is composed of a depth camera, a cooperative manipulator, and an electric claw. Finally, the two are coordinated and controlled by computer. The controller hardware of the mobile platform is designed, and the functional modules of the mobile platform are designed based on the RT thread embedded system. For the navigation part of the mobile robot, a fuzzy PID deviation correction algorithm is designed and simulated. Using the Hough circular transform algorithm, the visual grasping of the manipulator is realized. Finally, the control mode of the computer-controlled manipulator and the manipulator-controlling mobile platform is adopted to realize the feeding function of the mobile robot, and the experimental verification is carried out. [ABSTRACT FROM AUTHOR]

The use of ultra-short pulse lasers in the kW range, combined with an appropriate beam engineering approach, enables the achievement of high-throughput production of laser-functionalised surfaces. However, the manufacturing of complex parts still faces various challenges, such as difficulties in accessing regions with high aspect ratio shapes or intricate profiles, which often leads to the necessity of adapting the laser processing workstation to specific geometries. The forming process is a well-established technique for producing parts of any shape from metallic foils by imposing specific constraints. In this study, we aimed to assess the feasibility of producing laser-functionalised 3D complex products by the forming of laser-treated flat thin metallic sheets. Two-hundred micrometre-thick stainless-steel foils were textured with laser-induced periodic surface structures (LIPSS) through a roll-to-roll pilot line. First, we optimized the morphology of LIPSS. Subsequently, we conducted three types of mechanical tests on both laser-treated and untreated foils: standard tensile tests, fatigue tests, and cruciform specimen tests. We measured and compared parameters such as ultimate tensile strength, breaking strength, maximum elongation, and area reduction between specimens with and without LIPSS, all obtained from the same foil. Additionally, we utilized scanning electron microscopy (SEM) to compare the LIPSS morphology of laser-treated samples before and after mechanical tests. [ABSTRACT FROM AUTHOR]

Purpose: Assembly lines are widely employed in manufacturing processes to produce final products in a flow efficiently. The simple assembly line balancing problem is a basic version of the general problem and has still attracted the attention of researchers. The type-I simple assembly line balancing problems (SALBP-I) aim to minimise the number of workstations on an assembly line by keeping the cycle time constant. Design/methodology/approach: This paper focuses on solving multi-objective SALBP-I problems by utilising an artificial bee colony based-hyper heuristic (ABC-HH) algorithm. The algorithm optimises the efficiency and idleness percentage of the assembly line and concurrently minimises the number of workstations. The proposed ABC-HH algorithm is improved by adding new modifications to each phase of the artificial bee colony framework. Parameter control and calibration are also achieved using the irace method. The proposed model has undergone testing on benchmark problems, and the results obtained have been compared with state-of-the-art algorithms. Findings: The experimental results of the computational study on the benchmark dataset unequivocally establish the superior performance of the ABC-HH algorithm across 61 problem instances, outperforming the state-of-the-art approach. Originality/value: This research proposes the ABC-HH algorithm with local search to solve the SALBP-I problems more efficiently. [ABSTRACT FROM AUTHOR]

Over the past decades, robotic automation has expanded in numerous industrial sectors; however, manufacturing operations involving the manipulation of non-rigid products are mostly preserved manual. The dynamic distortion of flexible objects underlines limitations in robot cognition and dexterity. Inspired by the gaps in composites industry automation, this paper presents a novel multifunctional robot end-effector for the robotic automation of composites layup. Aiming a holistic confrontation of layup challenges, the proposed end-effector incorporates tools for (a) the manipulation of sheet materials, like composite fabrics of variable dimensions; (b) the grasping of core materials, like foam blocks; (c) the handling of peripheral tools; (d) the exertion of fitting forces; and (e) the application of resin in diverse mold geometry cavities. The meticulous design of the end-effector's configuration allows for consistent and collision-free tool usage with no excess robot tool changes, granting even higher productivity and efficiency. The enhancement in robot dexterity and proficiency for layup operations is validated within an automotive case, where semi-automation is intended for the improvement in overall workstation's efficiency, quality, ergonomics, and well-being. [ABSTRACT FROM AUTHOR]

In this study, a queue management model/software was developed for automobile repair shops. This software minimizes both waiting time of customers, and idle time of workers. The software groups all jobs done in an automobile repair shop into three sections: mechanical, electrical and air conditioning (A/C) sections. The developed software prioritizes all jobs performed in a typical automobile repair shop in terms of urgency, using the 'shortest processing time' scheduling approach. The jobs are then ranked and assigned to workers based on number of available workstations. Also, expected time of delivery of the job is estimated by the software. The software was tested using data obtained over a two weeks period and percentage reduction in waiting time was found to range between: 0.889-0.122, 0.895-0.25 and 1-0.167 for the mechanical, electrical and A/C sections respectively. In the mechanical section, servicing/replacement of piston and rings and changing/servicing of gear box were discovered to be the jobs with maximum delivery time (15 hrs) while changing of engine belt was seen as the job with the least delivery time (0.3 hrs). For the electrical section, changing of alternator, with delivery time of 3 hrs 30 mins and changing of headlamp and fuse breakage with delivery time of 0.15 hrs are the jobs with maximum and minimum delivery times respectively. For the A/C section, changing of freezer with delivery time of 10 hrs and refilling of gas with delivery time of 0.10 hrs are the maximum and minimum respectively. Implementation of this research will reduce time wastage experienced by customers, idle time at service facilities, frustration caused by unnecessary queue, and encourage allocation of resources accordingly. [ABSTRACT FROM AUTHOR]

Parts kitting is a frequently adopted method to feed parts from a warehouse to an assembly line. While kitting allows minimisation of space occupation and Work In Process holding cost at the workstations, also simplifying materials flow and supporting manual assembly, it is penalised by high workforce cost for manual kits preparation. For this reason, automated kitting systems have been also proposed although their practical application is somewhat limited owing to the relevant capital investment and scarce performances of robotised kitting systems. Moreover, economic models allowing a quantitative comparison of manual and automated kitting systems are not yet available in the literature. As a contribution to fill this gap, in this paper a cost model useful to compare manual and automation-assisted parts retrieval and kitting systems is presented. The model can be used as a decision-making tool when planning and justifying kitting systems. The model includes capital investment, workforce, space occupation and quality costs. A case study as an application example is also included to demonstrate the model capabilities. Results show that automation-assisted kitting systems can be competitive in comparison to manual kitting and that break-even conditions can be also identified by the proposed method. [ABSTRACT FROM AUTHOR]

Background: Sedentariness has been shown to increase energy intake and is associated with increased obesity prevalence. Active workstations are used to implement physical activity interventions in workplaces, but it is unclear if they can lead to reductions in body weight. This study aims to observe the acute impact of a standing desk on energy intake and appetite sensations. Methods: Participants came to the laboratory, where they were randomly assigned to a seated or a standing desk. They completed a work session (∼75 min) during which they performed cognitive tasks and reported their levels of stress. Following this, they had a 15-minute break during which buffet-type snacks were served. Subjects were asked to rate their appetite sensations on visual analog scales. Results: Thirty-six normal-weight men and women aged 24.3 (4.3) years participated in this study. Energy intake from snacks was similar (P =.472) between participants who sat (427.8 [286.9] kcal) and the ones who stood (461.2 [272.8] kcal) during the work session. There was no difference in satiety quotients around the snack and no significant interaction time × condition for appetite sensations. Conclusion: The use of a standing desk for 75 minutes did not increase food consumption following a meal. [ABSTRACT FROM AUTHOR]

We draw on cognitive and behavioural theories and on the artificial intelligence literature in order to propose a framework of future operator – workstation interaction in the 'Industry 4.0' era. We name the proposed framework 'Operator – Workstation Interaction 4.0'. The latter's capabilities permit an adaptive, ongoing interaction that aims to improve operator safety, performance, well-being, and satisfaction as well as the factory's production measures. The framework is composed of three subsystems: (1) the observation subsystem which observes the operator and the processes occurring in the workstation, (2) the analysis subsystem which generates understanding and implications of the observations output, (3) the reaction subsystem which determines if and how to respond. The paper describes these elements and illustrate them using an example of a fatigued worker. The contributions, implications, and limitations of the proposed framework are discussed, and future research directions are presented. [ABSTRACT FROM AUTHOR]

This article proposes a design method for a valve automatic assembly production line in response to the automation assembly requirements of electric valve products in space propulsion systems and the engineering problems of inaccurate loading force control and low valve measurement accuracy in existing process methods. This method can achieve five assembly processes during the assembly process of electric valves, including pre-tightening force control, valve-core stroke measurement, performance testing, and shell structure welding. The article introduces the design of platform components such as process execution, positioning, and transportation, as well as the design and operation process of workstations. By combining the design of a three-axis motion mechanism, a small turntable, and a robotic arm, the product can achieve professional, positioning, full process automation, and equipment miniaturization design across multiple workstations. Through the design of precise control of loading force and non-contact optical measurement method of moving structure, compared with the original method, the parameters affecting product performance are precisely controlled and the precision is improved. And the multivariable decoupling of valve product performance is realized by this method. Through application verification, this automatic assembly production line can significantly improve the assembly efficiency of electric valve products and solve difficult problems in product engineering. [ABSTRACT FROM AUTHOR]

Copyright of DYNA - Ingeniería e Industria is the property of Publicaciones Dyna SL and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Modern implementations of industrial robots require the use of extensive knowledge and novel concepts. To bring real benefits, robotized processes must be analysed in detail. This paper presents a preliminary study on the analysis of electric energy consumption of an industrial robot in the alternative palletization processes. Firstly, the robotization of manufacturing processes aspect was discussed and advantages of the robotic palletizing process were presented. Secondly, the utilized off-line robot programming environment and a model of the robotic workstation used during the study were described. Conducting analyses based on the alternative arrangement of elements in a pallet layer allowed discussion and the formulation of important conclusions. The research has confirmed the validity of detailed analysis of robotic production processes. [ABSTRACT FROM AUTHOR]

Biomechanical overload is considered a significant occupational risk in manufacturing and a potential cause of musculoskeletal disorders. This research aims to introduce new methodologies for the quantitative risk evaluation of biomechanical risk by combining surface electromyography with a motion acquisition system based on inertial measurement units. Due to the lack of experimental data in the literature acquired in a real industrial environment during the working shift, an on-the-field study regarding an automotive assembly line workstation has been carried out in collaboration with Fiat Chrysler Automobiles Italy S.p.A. Data related to the trunk flexion forward and the erector spinae muscle activity have been acquired for several consecutive working cycles by considering three different workers. Data analyses indicated kinematic and muscular activity patterns consistent with those expected and that the proposed wearable technologies can be integrated and used simultaneously during work activities. Furthermore, the results demonstrated data repeatability, strengthening the feasibility and usefulness of the combined use of kinematic and electromyography technologies to assess biomechanical overload in production lines. This study could lay the bases for the future definition of a method for assessing biomechanical overload due to awkward postures. [ABSTRACT FROM AUTHOR]

Background: An assembly line is a technique used in mass production industries, especially in the automotive industry; it consists of many workstations organized along a conveyor belt system or other material handling equipment. The assembly line balancing problem (ALBP) involves assigning assembly tasks to workstations on the line while meeting optimization goals. It is considered a critical issue in operations management because it directly affects the productivity of the entire manufacturing system. Methods: Based on the mathematical model previously developed by (Esmaeilbeigi, Naderi, and Charkhgard 2015) for the E-type SALBP problem, we proposed a new model adaptable to the automotive sector. The proposed model uses new feasibility rules and optimizes constraints in order to propose better balancing results and efficiency. Results: A computational experiment is presented in this article, using the newly developed model to balance an assembly line in an automotive manufacturing plant consisting of 5 workstations. Conclusions: The experimental results show that the proposed model improved the line efficiency by 15%, which proves that the proposed method has good robustness. [ABSTRACT FROM AUTHOR]

Staff in manufacturing sites not only need certain physical requirements for their allotted tasks but also utilise a large amount of information processing in the looming industrial age 4.0. This work established the Principles of Information Processing Economy in the production process and proposed a framework model of integrated complexity evaluation method for the production process, which combines both physical and cognitive loads while accounting for the effect of time stress. The method proposed in this study can be used for ergonomics evaluation of workstations. Compared with traditional evaluation methods, this method has good flexibility to account for the changes in labour loads in the industrial 4.0 eras and the role of various intelligent auxiliary systems. The proposed operational framework model can provide useful information for task assignment, operator selection and training, work organisation, and performance prediction. [ABSTRACT FROM AUTHOR]

Performance evaluation, and in particular cycle time estimation, is critical to optimise production plans in high-tech manufacturing industries. This paper develops a new aggregation model based on queuing network, so-called queue-based aggregation (QAG) model, to estimate the cycle time in a production system. Multiple workstations in serial and job-shop configurations are aggregated into a single-step workstation. The parameters of the aggregated workstation are approximated based on the parameters of the original workstations. Numerical experiments indicate that the proposed QAG model is computationally efficient and yields fairly accurate results when compared to other aggregation approaches in the literature. [ABSTRACT FROM AUTHOR]

The safety hazards existing in the process of disassembling waste products pose potential harms to the physical and mental health of the workers. In this article, these hazards involved in the disassembly operations are evaluated and taken into consideration in a disassembly line balancing problem. A multi-objective mathematical model is constructed to minimise the number of workstations, maximise the smoothing rate and minimise the average maximum hazard involved in the disassembly line. Subsequently, a Pareto firefly algorithm is proposed to solve the problem. The random key encoding method based on the smallest position rule is used to adapt the firefly algorithm to tackle the discrete optimisation problem of the disassembly line balancing. To avoid the search being trapped in a local optimum, a random perturbation strategy based on a swap operation is performed on the non-inferior solutions. The validity of the proposed algorithm is tested by comparing with two other algorithms in the existing literature using a 25-task phone disassembly case. Finally, the proposed algorithm is applied to solve a refrigerator disassembly line problem based on the field investigation and a comparison of the proposed Pareto firefly algorithm with another multi-objective firefly algorithm in the existing literature is performed to further identify the superior performance of the proposed Pareto firefly algorithm, and eight Pareto optimal solutions are obtained for decision makers to make a decision. [ABSTRACT FROM AUTHOR]

Characterising existing approaches to operational complexity, it can be stated that for those metrics are characterful different factors used as variables such as product structure, machine composition, number of technological functions performed by machine, and others. Moreover, the complexity metrics using the information content as a basis can be divided into two groups: those which define complexity as an absolute entropy quantity, and metrics defining complexity as the relative entropy magnitude. Our view on the operational complexity is based on an assumption that process complexity value obtained as a sum of the partial complexities is not so important than a balanced operational complexity value expressing relative quantity to equilibrium levels. Accordingly, this paper introduces the novel operational complexity measure that initially identifies operational complexities of individual machines based on the number of parts, machines and operations. In the subsequent steps, these sub-measures are used to define summary complexity measure involving two balanced operational complexity characteristics. The novel measure can be effectively used to find the most suitable layout design alternative. For the purpose to prove its effectiveness, on two practical cases where tested its practicability by comparing it to the complexity indicator expressing the sum of the partial complexities. [ABSTRACT FROM AUTHOR]

Effective conduct with End of Life (EOL) products is a hot research topic in green and smart manufacturing. For EOL product recycling and remanufacturing, a fundamental problem is to design an efficient disassembly line under consideration of stochastic task processing times. This problem focuses on selecting alternative task processes, determining the number of opened workstations, and assigning operational tasks to the workstations. The goal is to minimise the total cost consisting of workstation operational cost and hazardous component processing cost. Most existing works assume that the probability distribution of task processing times can be estimated, however, it is often not likely to access the complete probability distribution due to various difficulties. Therefore, this study investigates disassembly line design with the assumption that only the mean, standard deviation and an upper bound of task processing times are known. Our main contributions include: (i) a new decomposition color graph is proposed to intuitively describe all possible processes, (ii) a new distribution-free model is proposed, and (iii) some problem properties are established to solve the model. Experimental results show that the distribution-free model can effectively deal with stochastic task processing times without given probability distributions. [ABSTRACT FROM AUTHOR]

The optimisation problems related to the assignment of tasks to workstations in assembly and disassembly lines have been largely discussed in the literature. They are known, respectively, as Assembly Line Balancing and Disassembly Line Balancing Problems. In this study, both types of task performed on the identical product are integrated in a common hybrid production system. Therefore, the logistic process is simplified and disassembly tasks can supply easier the assembly tasks with the required components. The considered production system has the layout of two parallel lines with common workstations. The product flow is conventional in the assembly line and reverse in the disassembly line. The paper provides a new mathematical model for designing such a hybrid system and an approximate approach based on ant colony optimisation for solving large-scale instances. The solution method is tested in a case study. The obtained results are compared with the solution provided by the design of two independent lines. The analysis of the results highlights the potential benefits of the hybrid production system. [ABSTRACT FROM AUTHOR]

Manufacturing companies' preparedness level against external and internal disruptions is complex to assess due to a lack of widely recognized or standardized models. Resilience as the measure to characterize preparedness against disruptions is a concept with various numerical approaches, but still lacking in the industry standard. Therefore, the main contribution of the research is the comparison of existing resilience metrics and the selection of the practically usable quantitative metric that allows manufacturers to start assessing the resilience in digitally supported human-centered workstations more easily. An additional contribution is the detection and highlighting of disruptions that potentially influence manufacturing workstations the most. Using five weighted comparison criteria, the resilience metrics were pairwise compared based on multi-criteria decision-making Analytic Hierarchy Process analysis on a linear scale. The general probabilistic resilience assessment method Penalty of Change that received the highest score considers the probability of disruptions and related cost of potential changes as inputs for resilience calculation. Additionally, manufacturing-related disruptions were extracted from the literature and categorized for a better overview. The Frequency Effect Sizes of the extracted disruptions were calculated to point out the most influencing disruptions. Overall, resilience quantification in manufacturing requires further research to improve its accuracy while maintaining practical usability. [ABSTRACT FROM AUTHOR]

Copyright of Journal Industrial Engineering / Revista de Ingeniería Industrial is the property of ECORFAN-Mexico S.C. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper, an integrated approach for assembly line rebalancing problem (IALRP) is proposed to quickly react and find an optimal rebalancing of the line when disruptive event occurs because of product demand changes. This model is motivated by real-life application of an automotive cable manufacturer which provides more realistic constraints. To solve the problem, we propose a genetic algorithm (GA) hybridised with a heuristic priority rule-based procedure. This hybridisation is used to add more rich seeds to the initial population and consequently to improve the convergence capability and performance of the GA. After the disturbance, we aim to find a rebalance with the proposed approach to maximise the line efficiency and distributing the idle time across the workstations as equally as possible. To evaluate the efficiency of the proposed algorithm, set of samples collected from the literature are used. The real case study and the experiment results show the proposed approach is very effective and competitive. [ABSTRACT FROM AUTHOR]

A line balancing problem considers the assignment of operations to workstations in an assembly line. While assembly lines are usually associated to mass production of standardised goods, their advantages have led to their widespread use whenever a product-oriented production system is applicable and the benefits of the labour division and specialisation are significant, even when some of its characteristics may deviate from classical assembly lines. In this work, we study a line balancing problem found in the textile industry in which the line must be balanced for multiple types of goods taking into account resource requirements. In order to solve the problem, a hybrid method that combines classical methods for line balancing with an Estimation of Distribution Algorithm is proposed. Computational experiments show that the new procedure improves upon the state of the art when compared using a benchmark set derived from the literature, as well as when compared using data from the manufacturer that originated this research work. [ABSTRACT FROM AUTHOR]

This paper considers the assignment of heterogeneous workers to workstations of an assembly line in order to minimise the total production time. As the structure of the system implies that each of the workstations needs at least one worker, thus the problem can be considered as a generalised assignment problem (GAP). The objective is to perform an efficient human resource planning for a specified horizon consisting of several periods. Hence, we present an extension of the generalised assignment problem, consisting of a set of GAPs (one for each planning period) in which each GAP depends on the previous ones. A mixed integer mathematical model is presented for this sequencing assignment problem. The model is solved by an exact algorithm using Gurobi solver. It is proved that the problem is NP-hard and solving the medium and large size instances is not possible by the exact algorithms. Hence, two matheuristic approaches based on the disaggregated formulation of GAP are proposed. The first approach solves the problem through two sub-problems as the transportation formulation and assignment formulation. The second approach solves the problem by decomposition of the problem into several classical GAPs. The approaches are examined by a total of 27 instances. The results illustrate the efficiency of the proposed algorithms in the computational time and accuracy of the solutions. [ABSTRACT FROM AUTHOR]

In industrial production, minimizing the idle time during assembly line reorganization in product switching is very important for management organizations. To increase efficiency, instead of taking the products that are expected to be produced in different and numerous varieties into the assembly line in indiscriminate order, it is necessary to schedule them in the order that requires the minimum setup time and start production in this way. In this study, the problem of minimizing machine setup time in assembly line workstations in product switching is mathematically modeled, and the problem is proved to be from the NP-hard class. In addition, 3 modified heuristic algorithms and 2 hybrid genetic algorithms are presented for the problem of product switching processes, and their performance is compared by running on 20 test problems. [ABSTRACT FROM AUTHOR]

The article presents the discussion on Demmeler Maschinenbau GmbH & Co. KG, Heimertingen, the company doing arc welding. Topics include solution being a partial automation of the manual welding workstations; and containing automotive, railway, mechanical and plant engineering, conveyor technology, furniture industry, and the metal construction.

We study robotic mobile fulfilment systems for online retailers, where products are stored in movable shelves and robots transport shelves. While previous studies assume random assignment rule of workstations to robots, we propose an assignment rule based on handling speeds of workstations and design a neighbourhood search algorithm to find a near optimal assignment rule. We build semi-open queueing networks and use a two-phase approximate approach for performance estimation. We first replace workstation service processes by a composite service node and then solve the model by the matrix-geometric method. Simulations are used to validate the analytical models. Numerical experiments are conducted to compare random, handling-speeds-based, near optimal and optimal assignment rules, in terms of retrieval throughput time. The results show that the random assignment rule is not a good choice, the handling-speeds-based assignment rule significantly outperforms the random assignment rule when the workers have large handling time difference, and the neighbourhood search approach can provide an assignment rule that is very close to the optimal one, using a much shorter time. Moreover, we design the shelf blocks under the examined assignment rules, and find that the optimal width of shelf block decreases with the width to length ratio. [ABSTRACT FROM PUBLISHER]

In this study, we consider an assembly line rebalancing problem with disruptions caused by workstation breakdowns or shutdowns. After the disruption, we aim to find a rebalance so as to catch the trade-off between the efficiency measure of cycle time and stability measure of number of tasks assigned to different workstations in the original and new balances. Our aim is to generate all nondominated objective vectors with respect to the efficiency and stability measures. We develop two optimisation algorithms: a Mixed Integer Linear Programming-based algorithm and a Branch and Bound algorithm. The results of our experiments have shown the favourable performances of both algorithms and the superiority of the Branch and Bound algorithm. [ABSTRACT FROM PUBLISHER]