Assembly Shop Research Articles

Studies of Application of LED-Based Lighting Devices in a Car Assembly Shop

The article describes the problem of replacement of active fluorescent lamp lighting installations of an assembly line of a car assembly plant with LED LDs including a comparison of the gained lighting and economic indicators. Therefore, several LED-based LDs by different manufacturers were selected. Based on LI computer modelling using DIALux Evo, an optimal option in terms of light engineering and economy was found. Lighting characteristics of the active LI and areas of the assembly line with the application of LED-based LDs were determined experimentally. The results of the study allow assessing relevant changing of visual performance of shop workers and to compare the pay-off periods of LED and fluorescent lamps-based lighting devices.

A hybrid optimization approach for unequal-sized dynamic facility layout problems under fuzzy random demands

Dynamic facility layout problems involve devising the optimal layout for each different production period. This article studies unequal-area dynamic facility layout problems under fuzzy random environment to minimize the sum of the material handling costs and rearrangement costs. For a more general situation, a novel model of unequal-area dynamic facility layout problems is proposed on the basis of fuzzy random theory, in which uncertain demands are characterized by fuzzy random variables. Unequal-area dynamic facility layout problems are one of the non-deterministic polynomial-time hard problems. Therefore, a hybrid particle swarm optimization and simulated annealing algorithm is innovated to solve the proposed unequal-area dynamic facility layout problems model under fuzzy random environment, in which the shapes and areas of facilities are changed dynamically. Two facility-swapping methods and two local search methods help hybrid algorithm escape from local optima, allowing a more reliable solution. Moreover, a new shifting method is developed to prevent the spatial overlapping between adjacent facilities and save material handling costs. The performance of the hybrid algorithm is confirmed by some test problems available. Finally, the proposed method is extended to a facility layout planning of a new aircraft assembly shop floor. Computational results show that the efficiency and effectiveness of the proposed method, in sharp comparison with other approaches.

Criteria for ensuring acoustic safety in the assembly shops of machine-building enterprises

We consider the problem of providing acoustic safety at the machine-building enterprises, where manual pneumatic tools and electrical tools are widely used in assembly shops. As an example we considered the noise during operation of pneumatic tools, which are the most preferable from the point of view of ensuring electrical safety. The necessity of monitoring audiograms of operators performing assembly operations, repair and adjustment at the machine assembly lines is justified. We analyzed the types of the used pneumatic tools and their service life, measured the level of generated noise and compared the obtained data with the passport acoustic characteristics from manufacturer. As a result, we showed the need to take into account the operating characteristics of instrument while ensuring acoustic safety. The main criteria for acoustic safety are defined.

Value stream mapping method for development of a dynamic model of capacity utilization

For multi-product small-scale manufacturing, for example the production of electronic equipment, the searching of methods and tools for production planning is relevant. One of the basic tools for planning is the model of enterprise capacity utilization. The purpose of this research is to develop a model and software allowed the company to calculate the optimal capacity utilization. The paper considers the use of value stream mapping method for development of a manufacturing dynamic model. This method allows creating the interaction logic and collecting data and parameters for each system components. The purpose of the value stream analysis is to find a transit solution from the current production state to a more efficient, which allows loading the production capacity in optimal mode. In the analysis, the manufacturing data of the finished products assembly shop of a radio-electronic enterprise is used. According to the results of use the proposed method, the duration of the assembly process was significantly reduced, which makes it possible to equalize the load of work centers and to reduce the volume of unfinished production.

Research on Scheduling Problem of Discrete Manufacturing Workshop for Major Equipment in Complicated Environment

This paper studies the scheduling problem of discrete equipment manufacturing workshops for major equipments in the context of commercial aircraft engine assembly workshops. At present, the manufacturing process of aircraft engines is still based on manual assembly, involving a large number of tooling parts, the workshop has large flow and long assembly period but limited labor. In this paper, the production scheduling process is optimized under the condition of multi-skilled human resources constraints. The mathematical programming model is established by abstracting the problem, and a heuristic algorithm based on multi-priority rules suitable for this problem is selected to solve the problem. Then, using Plant Simulation to establish a simulation model for the actual discrete assembly system, input different scheduling schemes and combine the logistics process for collaborative verification, and analyze the best scheduling results as a guide. The research shows that this method can effectively guide the workshop operation process, adapt to the constantly adjusted workshop layout, improve the resource utilization rate and assembly efficiency, and has a strong reference for practical application.

Worker assignment in dual resource constrained assembly job shops with worker heterogeneity: an assessment by simulation

Most shops in practice are constrained by more than one resource. Consequently, a large body of literature on dual resource constrained shops has emerged. This research typically focuses on worker assignment rules, with attention being on when and where to move workers. In contrast, the decision concerning who to reallocate to a station has received limited attention. The limited prior work assumes workers are assigned to a new station as soon as they become available or seeks to minimise the risk of worker idleness. Using simulation, we question this assumption and show that it can be beneficial to introduce additional worker idleness to ensure workers only work at their most efficient station(s). In general, it is less likely that there are several workers available for one station than it is for there to be multiple stations available for one worker. Consequently, the Who Rule is used less frequently than the Where rule and has less of an impact on performance. Finally, considering the criticality of work orders as part of the Where Rule is important in assembly shops; but if labour is heterogeneous then the focus should be on efficiency. The findings have important implications for research and practice.

A two-stage ant colony algorithm for hybrid flow shop scheduling with lot sizing and calendar constraints in printed circuit board assembly

This paper investigates a multi-stage hybrid flow shop scheduling problem with challenging characteristics including lot sizing, calendar constraints and sequence-dependent setup times in a real-world printed circuit board (PCB) assembly shop. Besides, other characteristics such as unrelated parallel machines and stage skipping also complicate the problem. Such features make the scheduling problem very difficult to find an optimal or near optimal solution. To reduce the complexity of such a PCB scheduling problem, this study develops a hierarchical approach which decomposes the original problem into two highly coupled sub-problems including job sequencing and lot scheduling with lot sizing, and further proposes a two-stage ant colony algorithm with lot sizing to evolve best results in the makespan performance. Extensive computational experiments have been conducted to illustrate the superiority of the algorithm in terms of computational time and stability.

Classification of Cyber and Physical Systems of Industry 4.0

The actual task is to create the classification system for cyber and physical technological equipment for smart factories of the Industry 4.0. Smart factories are a new type of production companies which work automatically. To project a smart factory they need to choose samples of cyber and physical systems of different purpose to unite them in automatic sections. To solve the choice task of production machine samples they need to create libraries of technical and tactical characteristics and its ontology description the base of which is the system to classify cyber and physical equipment. There is a classification scheme of industrial cyber and physical systems to work in a smart factory of item designing. The classification systems base is types of technological operations being realized in a company and also methods and technologies which the cyber and physical systems use. Cyber and physical systems functionality is described for mechanical treatment and assembly workshops of item designing company.

An Analytic Hierarchy Process Approach in Decision-Making for Material Selection in an Automotive Company: A Case Study

This study is an approach to investigate and to choose the suitable material for the fabrication of tools trolley to ensure the good quality of the product. The project team of an automotive manufacturing company is planning to fabricate 100 sets of tools trolley in the assembly shop. This study was developed to describe an approach based on Analytic Hierarchy Process (AHP) that can assist decision-makers and continuous improvement engineers in determining the most suitable material to be employed in fabrication process at the early stage of the product development to reduce the cost. The selected main criteria are Material Strength, Material Cost, Procurement Lead Time and Duration of Fabrication Process while the four materials that will be considered in this study are Aluminium, Steel Tube, and Square Tube. Finally, the results show that Square Tube is recommended as the most suitable material for the in-house tools for trolley fabrication.

Improved moth flame optimization algorithm to optimize cost-oriented two-sided assembly line balancing

Purpose This paper aims to propose an improved Moth Flame Optimization (I-MFO) algorithm to optimize the cost-oriented two-sided assembly line balancing (2S-ALB). Prior to the decision to assemble a new product, the manufacturer will carefully study and optimize the related cost to set up and run the assembly line. For the first time in ALB, the power cost is modeled together with the equipment, set up and labor costs. Design/methodology/approach I-MFO was proposed by introducing a global reference flame mechanism to guide the global search direction. A set of benchmark problems was used to test the I-MFO performance. Apart from the benchmark problems, a case study from a body shop assembly was also presented. Findings The computational experiment indicated that the I-MFO obtained promising results compared to comparison algorithms, which included the particle swarm optimization, Cuckoo Search and ant colony optimization. Meanwhile, the results from the case study showed that the proposed cost-oriented 2S-ALB model was able to assist the manufacturer in making better decisions for different planning periods. Originality/value The main contribution of this work is the global reference flame mechanism for MFO algorithm. Furthermore, this research introduced a new cost-oriented model that considered power consumption in the assembly line design.

Manufacturing conversion cost reduction using quality control tools and digitization of real-time data

Abstract: Two-wheeler automobile manufacturers in India are currently facing a big pressure to reduce the overall manufacturing cost in order to sustain the position in hypercompetitive domestic and global market. The manufacturing conversion cost is one part of the overall manufacturing cost. It consists of three major components i.e. product or parts scrap cost, consumables cost and tool cost. The scrap cost is the cost of defective products, which are not produced in accordance with standard and can't be sent to market. The consumables cost is the cost of other than basic raw material used in manufacturing i.e. filters, filler materials, fuel, gases, chemical, coolant and lubricants etc. This study has tried to emphasise role of conversion cost in making organisations cost competitive. Case study-based approach is used in this study. The case manufacturing system comprises three main processes: machine shop, frame plant (weld and paint shop) and assembly shop. In frame plant, paint shop and weld shop are the two main sub sections of this automobile manufacturing. More than 50% of overall manufacturing conversion cost is consumed in these two areas. This study attempts to illustrate the reduction of the manufacturing conversion cost by prioritizing and analysing the cost factors using DMAIC (define-measure-analyze-improve-control) approach using quality control (QC) tools like Pareto chart, Cause & effect diagram and digitization of real time data. Authors have identified eighteen elements of conversion cost in this study. It has been observed from this study that even small saving in conversion cost per vehicle i.e. INR 24.18 (0.35 US$) per vehicle has resulted in annual saving of 2.2 millionUSD.Initiatives taken by this organisation for cost saving has also resulted in cleaner production and more sustainable manufacturing processes. Findings will be motivating to other manufacturers for reducing manufacturing cost using QC tools on smaller and insignificant activities.

Reading Aviation Wire Text in Natural Images under Assembly Workshop via Deeplearning

Reading aviation wire text is an important step for aircraft wire assembly and also a challenging problem. Aviation wire text reading means to detect and recognize the serial number printed on the surface of aviation wires or aircraft cables. The main challenges of this task lie on small sizes, low contrast and background noise in images. In this paper, we propose a new method for aviation wire text detection and recognition via deep neural networks. The detection network utilizes text border features to roughly locate text regions in images. Then the coordinates of bounding boxes of texts are regressed by pixel-level predicted offsets in adjacent regions. The recognition network is capable to recognize the text regions with diverse lengths after padding strategies. In addition, a dataset of aviation wires captured by machine vision camera in the assembly workshop is developed. A flexible method to generate synthetic images of text whose characters are arranged in styles of both head-to-tail and left-to-right is presented. On aviation wire datasets, the proposed method for text detection and recognition achieves comparable performance and significantly outperforms previous approaches.

Modelling and Production Configuration Optimization for an Assembly Shop

Modelling and Production Configuration Optimization for an Assembly Shop

An occupational hazard of workers of wagon-repair production

Introduction. Professional groups of railway workers engaged in the repair of wagons are directly responsible for the safety of railway traffic. The analysis of literature testifies to insufficient attention of researchers to the hygienic problems associated with labor activity of workers of wagon-repair production.The aim of the study is to assess the occupational risk to the health of wagon repair workers, due to the impact on them of factors of the working environment and the labor process.Materials and methods. The study used comprehensive hygienic studies using the methodology of occupational risk to worker’s health.Results. The leading factors of the working environment (class of working conditions 3.2–3.4), which are exposed to workers depending on the specifics of the work performed. Identified professional groups with medium (significant) high (unbearable) and very high (intolerable) category of a priori occupational risk: in wagon meintenance workshop — 17 groups (94% of jobs), in a wagon assembly workshop — 11 groups (80% jobs), in wagon wheel workshop — 3 group (100% jobs). At the same time, according to the request for medical care, employees were diagnosed with isolated cases of occupational diseases.The levels of morbidity with temporary disability of employees of the main workshops are statistically significant (p<0.05) higher than those of the control group in 1.4–1.9 times. The influence of the complex of chemical factors of low and medium intensity on the levels of morbidity of respiratory diseases in the group of workers of the wagon wheel workshop, which were 1.7–2.0 times higher than in the control group, is confirmed by the average degree of causation of the production condition of this pathology (RR=1.7; EF=42.0%).The combined effect of vibration and severity of the labor process forms a high level of temporary disability of employees of the main workshops in connection with diseases of the musculoskeletal system, which was 2.7–4.4 times higher than in the control group, and also determines the prevalence of this pathology in the structure of diseases detected on medical examinations (23.2%). Diseases of the musculoskeletal system are caused by the production of employees of the wagon meintenance workshop (RR=3,9; EF=74,9%), as the most unfavorable in terms of hygiene on these factors.The stressful influence of the complex of harmful production factors on the health of wagon repair workers is manifested by the high risk of diseases of the cardiovascular system, gastrointestinal tract, neurological disorders, violation of adaptation of the cardiovascular system in 97% of the examined, as well as the predominance of diseases of the digestive system and circulatory system detected on periodic medical examinations.Conclusions. Harmful working conditions (class 3.1–3.4) cause the suspected occupational risk from small (moderate) to very high (intolerable) to 100% of the jobs of wagon repair workers. The results of the study of morbidity and risk of pathology indicate a significant risk of damage to the health of workers.

Comparative assessment of the dynamics of individual carcinogenic risk for workers of the main professions of wagon repair production

Introduction.Part of the population working at carcinogenic enterprises is exposed to double exposure to carcinogens (in industrial and domestic conditions), however, studies to assess the total inhalation exposure is practically not carried out.The aim of the studyis hygienic assessment of the contribution of working environment factors to the formation of individual carcinogenic risk (ICR) for workers in the main professions in the car repair company, including the assessment of the predicted values of occupational risks in the dynamics of work experience.Materials and methods. There was the calculation of the levels of ICR for workers of the main professions in the wagon wheel, wagon meintenance, wagon assembly workshops. The assessment of exposure for workers is given on long-term average concentrations in the air of the working area and on average annual concentrations in the atmospheric air. When calculating the doses of toxicants in the air of the working area, «standard» parameters of pulmonary ventilation for an adult, body weight, work experience in contact with carcinogenic substances — from 1 to 30 years, the number of days in contact — 240, working time — 8 hours (in accordance with the duration of the working day) were used.Results.Workers of major occupations carcinogenic enterprise levels ICR differ in dozens of times. Calculation of ICR at 30-year work experience showed that in all studied main and auxiliary professions the total ICR was in the 4th range (more than 1,0·10–3). Unacceptable values for the predicted ICR for the professions of «painter», «locksmith-electrician», «impregnator», «mechanic of rolling stock» begin with a 5-year work experience, the least carcinogenic is the work of a tinker, whose risk reaches an unacceptable level after 20 years of the work experience. Among the most dangerous jobs should be attributed to the wagon assembly workshop. In contribution to the ICR the leading carcinogens are benzene, nickel, formaldehyde.Conclusions:The problems of monitoring carcinogens in the production environment, expert assessments to prove the professional genesis of malignant neoplasms were considered; it is noted that the rank number of carcinogenic professions of wagon repair production is as follows: painter, electrician, impregnator, mechanic of rolling stock.

OPTICAL-ELECTRONIC DEVICE OF CALCULATION OF PARAMETERS OF VOLUME OBJECTS OF WORKING SCENE AT MULTIPLE SOURCES OF VIDEO DATA

The paper considers approaches to the construction of a geographically distributed optical-electronic device, providing an analysis of significant and long working scenes in the interests of automating the processes of control and management of robotic tools in industrial assembly shops and warehouses. The principal difference of the proposed solution is the possibility of obtaining images of the analyzed objects using optical-electronic sensors located in different parts of the workspace to realize the function of binocular vision on a much larger area of the working scene compared to analogues. A distinctive novelty of the developed theoretical approach is the approach to binocular technical vision, which consists in iteratively performing calibration procedures for selected pairs of opticalelectronic sensors and the subsequent calculation of the spatial coordinates of the objects being analyzed using calibrated pairs of optical-electronic sensors. The results of image analysis from each of the optoelectronic sensors are used to accompany moving objects and analyze their motion paths in the working scene space. To implement the developed theoretical approaches, a modular optoelectronic device has been developed, consisting of two types of modules. The first type of module is a standalone opto-electronic module, which includes an opto-electronic sensor and means for processing and extracting primary features immediately upon receiving images for their subsequent analysis. The second type is a computational module that provides processing of primary data from a set of modules of the first type. Data transfer between device modules is provided via radio over a WiFi network. A distinctive feature of the developed device is the primary processing of images immediately upon their receipt and transmission over the radio channel of a small amount of data about the selected objects to the computing module, which performs the final stages of data processing and generates a set of parameters describing the characteristics and spatial coordinates of the objects found on the working scene for their further of use. Experimental studies were conducted on the developed simulation model, which confirmed the correctness of the developed theoretical approach and the possibility of its application in practice.

Modelling and solving the job shop scheduling Problem followed by an assembly stage considering maintenance operations and access restrictions to machines

This paper considers job shop scheduling problem followed by an assembly stage and Lot Streaming (LS). It is supposed here that a number of products have been ordered to be produced. Each product is assembled with a set of several parts. The production system includes two stages. The first stage is a job shop to produce parts. Each machine can process only one part at the same time. The second stage is an assembly shop that contains several parallel machines. Maintenance operations and access restrictions to machines in the first stage are also considered. The objective function is to minimize the completion time of all products (makespan). At first, this problem is described and modelled as a mixed integer linear programming, and GAMS software is applied to solve small-sized problems. Since this problem has been proved to be strongly NP-hard, two new algorithms based on GA and SA are developed to solve the medium- and large-sized problems. In order to verify the effectiveness of the proposed algorithms, a statistical analysis is used along with Relative Percentage Deviation (RPD) factor and well-known criterion. IMP. Various problems are solved by the proposed algorithms. Computational results reveal that both of the two proposed algorithms have good performance. However, the method based on the genetic algorithm performs better than the other proposed algorithm with respect to the objective functi

Optimization Algorithm of UWB Positioning for Aircraft Assembly Workshop

Due to the complexity of strong metal interference and multiple occlusions in aircraft assembly workshop, the random 'drift' phenomenon often happens in the ultra wide band (UWB) based positioning system. To solve this, a fusion positioning optimization algorithm is proposed based on median filtering, hidden Markov model (HMM) and Kalman filtering. Firstly, based on the three-dimensional (3D) median filtering, a queue optimization method with weights is introduced to smooth the measurement data and eliminate the abnormal value. Secondly, taking Singer model as a reference, a single-dimension acceleration distribution model is designed. In order to further consider the spatial motion characteristics of objects in workshop, the distribution is extended from 1D to 3D, and discretized into the state quantity of HMM. Subsequently, the data obtained by the two methods are fused by taking Kalman filter as an iterator, and then the optimized location solution is obtained based on dynamic weights. Finally, an experiment is conducted in an aircraft assembly workshop. Results show that 99.3% of dynamic positioning errors are less than 15 cm after using the proposed algorithm. Even in the situation with large signal-fluctuation, there are 71.6% of positioning data whose errors are reduced. The random 'drift' is greatly decreased.

Manufacturing excellence in the Indian automobile industry through sustainable lean manufacturing: a case study

Sustainable lean manufacturing (SLM) in automobile industry is an important pillar of survival in this competitive world. SLM has focused on profit of an organisation by ensuring sustained good quality products and meeting customer demands. In a competitive era, the present study focuses on developing a practical implementation of SLM and explains its practical implementation through descriptive models drawn by the researchers. This study focuses on implementation of lean manufacturing in the automotive industry in the assembly, machining and moulding shops. It special deals with all kinds of waste (overproduction, inventory, waiting, rework and rejection) in the industry. After analysing the waste level, it focuses on factors important to implementing lean manufacturing and provides a draft list of factors in the areas where the industry is found to have some gaps. With the help of an earlier research model, the lean implementation Gantt chart is made following the researcher's guidelines. After lean implementation, waste in industry is reduced as per the target setting; and the focus now shifts to sustainability of the implemented action. The changes added for sustainability of the system constitute guidelines so that if there is any change in organisation actions, sustainability is still ensured.

Assessment of implementation of Lean Manufacturing in manufacturing unit-A case study

Lean manufacturing is a performance-based strategy for maximising customer value by elimination of waste, while improving profitable growth of the organisation. The present study has been carried out at recliner assembly shop of an automobile manufacturing industry in North India with an aim to develop and implement lean manufacturing program in a systematic manner. The systematic procedure has been adopted to identify wastes, their reasons of occurrence and selection of suitable methods adopted for their removal. The recommendations of experts have been implemented by conducting a tack time study of recliner assembly process which reduced inventory by 14% by line balancing. The divisions of customer's monthly requirements into week plans has improved the tool setup time by 29% and reduced working delay. Administrative controls have been implemented to conduct in house training sessions of workers that had reduced absenteeism by 15%.