Design Of Manufacturing Systems Research Articles

Design and Development of a Flexible Manufacturing System

Abstract: In most organizations, a flexible manufacturing system (FMS) is concerned with the automatic production of different parts in the middle range because it is flexible. In a nutshell, it's a machine that makes everything. FMS relies heavily on the flow of jobs and tools in order to function. The FMS work centre can handle a large number of tasks at once. For FMS facilities, a tool magazine is in use as a means of reducing tool inventory. We present the Jaya method in this work to schedule tasks and tools simultaneously without considering tool transfer delays across machines; this is what we call the make span goal. On numerous make span-related challenges, the suggested heuristic is evaluated and compared with current approaches. The suggested heuristic beats the already used approaches, according to the findings. Keywords: “Flexible Manufacturing System”, “Automation” performance, Manufacturing, flexibility

Digital twin framework for reconfigurable manufacturing systems (RMSs): design and simulation.

Faced with the global crisis of COVID-19 and the strong increase in customer demands, competition is becoming more intense between companies, on the one hand, and supply chains on the other. This competition has led to the development of new strategies to manage demand and increase market share. Among these strategies are the growing interest in sustainable manufacturing and the need for customizable products that create an increasingly complex manufacturing environment. Sustainable manufacturing and the need for customizable products create an environment of increased competition and constant change. Indeed, companies are trying to establish more flexible and agile manufacturing systems through several systems of reconfiguration. Reconfiguration contributes to an extension of the manufacturing system’s life cycle by modifying its physical, organizational and IT characteristics according to the changing market conditions. Due to the rapid development of new information technology (such as IoT, Big Data analytics, cyber-physical systems, cloud computing and artificial intelligence), digital twins have become intensively used in smart manufacturing. This paper proposes a digital twin design and simulation model for reconfigurable manufacturing systems (RMSs).

Multi-Objective Design Optimization of Flexible Manufacturing Systems Using Design of Simulation Experiments: A Comparative Study

One of the basic components of Industry 4.0 is the design of a flexible manufacturing system (FMS), which involves the choice of parameters to optimize its performance. Discrete event simulation (DES) models allow the user to understand the operation of dynamic and stochastic system performance and to support FMS diagnostics and design. In combination with DES models, optimization methods are often used to search for the optimal designs, which, above all, involve more than one objective function to be optimized simultaneously. These methods are called the multi-objective simulation–optimization (MOSO) method. Numerous MOSO methods have been developed in the literature, which spawned many proposed MOSO methods classifications. However, the performance of these methods is not guaranteed because there is an absence of comparative studies. Moreover, previous classifications have been focused on general MOSO methods and rarely related to the specific area of manufacturing design. For this reason, a new conceptual classification of MOSO used in FMS design is proposed. After that, four MOSO methods are selected, according to this classification, and compared through a detailed case study related to the FMS design problem. All of these methods studied are based on Design of Experiments (DoE). Two of them are metamodel-based approaches that integrate Goal Programming (GP) and Desirability Function (DF), respectively. The other two methods are not metamodel-based approaches, which integrate Gray Relational Analysis (GRA) and the VIKOR method, respectively. The comparative results show that the GP and VIKOR methods can result in better optimization than DF and GRA methods. Thus, the use of the simulation metamodel cannot prove its superiority in all situations.

Evaluation of ridge lap accuracy and adaptation of the diagnostic tooth arrangement fabricated with CAD-CAM systems: An in vitro study

Statement of problemDigital light processing (DLP) and milling (MIL) are computer-aided design and computer-aided manufacturing (CAD-CAM) systems that have become popular for fabricating definitive complete dentures. However, few studies have compared the accuracy of the ridge laps of diagnostic tooth arrangements fabricated with these systems and their adaptation with the denture base sockets. PurposeThe purpose of this in vitro study was to comparatively analyze the accuracy of the ridge laps of the diagnostic tooth arrangements fabricated by using MIL and different layer thicknesses in DLP. Material and methodsA virtual definitive complete denture was designed with a CAD software program on a scanned virtual digital cast, divided into diagnostic tooth arrangement and a denture base that accommodated the arrangement, and saved as a standard tessellation language (STL) file. From this file, 27 diagnostic tooth arrangements were fabricated by DLP (50 μm and 100 μm) and MIL. The ridge laps were scanned and overlapped on the file (reference data) to analyze the accuracy (trueness and precision). The ridge laps of all groups were overlapped on the reference denture base data to analyze their adaptation with the sockets. The measurements of the trueness, precision, and adaptation were analyzed statistically by using the nonparametric Kruskal-Wallis test and post hoc Mann-Whitney U test with Bonferroni correction. ResultsThe diagnostic tooth arrangements showed significant differences among the groups (P<.001). The values were the lowest in the MIL group and highest in the DLP group for the following parameters: trueness root-mean-square (RMS) value, 173 ±7 μm versus 286 ±15 μm; precision RMS value, 22 ±3 μm versus 57 ±20 μm; and adaptation RMS value, 41 ±5 μm versus 112 ±13 μm. ConclusionsOf the 2 diagnostic tooth arrangements fabricated with the CAD-CAM systems, the one fabricated with MIL was clinically more appropriate.

Fatigue Resistance of 3-Unit CAD-CAM Ceramic Fixed Partial Dentures: An FEA Study.

To estimate the fatigue life of 3-unit molar fixed partial dentures (FPDs) made from two different monolithic ceramic systems, zirconia cercon (ZC) and lithium disilicate (LD). The effect of the connector size on the fatigue resistance of the monolithic FPD was also investigated. Two models for the FPDs were built, a 3-unit all-ceramic and a porcelain-fused-to-metal. The porcelain-fused-to-metal FPD model was used as the control. Actual 3-unit FPDs (replacing the second lower premolar) were constructed using a computer aided design and computer-aided manufacturing (CAD-CAM) system. Finite element analysis (FEA) was executed. A hemispherical indenter was used to simulate occlusal load. The occlusal load phase of the chewing cycle was applied at the premolar pontic. The failure location for the monolithic FPD was always located at the distal connector. Connector size played a key role in determining the long-term survival of the prosthesis. The fatigue resistance was predicted to be 670 N for the ZC with a connector size 4 × 3 mm, while it was only 226 N for LD. As for porcelain-fused-to-metal (PFM), FEA predicts that fatigue resistance can reach up to 770 N. Under the cyclic load of 670 N, the fatigue life for the zirconia FPD with connector size 4 × 3 mm was 2.23 × 106 cycles while it survived only 3.1 × 105 cycles when the connector was reduced to 3.5 × 2.5 mm. The angle of the oblique load has a significant effect on the stress distribution. 3-unit monolithic FPDs made of ZC have superior fatigue performance compared to those made of LD. The fatigue life of the zirconia FPD was about three times longer than that made of LD with a connector size of 4 mm × 3 mm. The survival rates of ZC FPDs are comparable to porcelain-fused-to-metal. A significant reduction in fatigue strength is predicted for reduced connector size. Therefore, it is necessary to establish general guidelines for the minimum connector size.

Machine learning integrated design and operation management for resilient circular manufacturing systems

The implementation of smart manufacturing devices in the manufacturing industry has provided an effective and intelligent way to monitor their facilities and thus control their integrated manufacturing processes. Despite the ongoing technological advancements, the same industry is often involved with complex problems that are associated with increasing costs related to the persistent deterioration of the manufacturing/remanufacturing systems. In literature, these systems are often called “circular manufacturing systems”. Furthermore, this deterioration affects the quality of the manufactured products. To address these problems, a novel integrated design and operation management-based framework is introduced in order to obtain joint policies for the authorization of production, recycling, maintenance and remanufacturing activities in the context of deteriorating circular manufacturing systems. This framework utilizes a reinforcement learning technique and ad-hoc production control policies, such as Base Stock and CONWIP, in an effort to improve the flexibility and the resilience of the examined systems to the ever-changing customer demand. Finally, a series of simulation experiments evaluate the behavior and the efficiency of the proposed mechanism within the context of single-stage and 2-stage deteriorating manufacturing/remanufacturing systems. Results suggest that the presented approach can effectively generate sufficient inventory of ready-to-be-sold products due to the enhanced awareness of the ongoing customer demand compared to the traditional reinforcement learning joint control.

Evaluation of mechanical properties of dental zirconia in different milling conditions and sintering temperatures

Statement of problemThe dry processing of zirconia has the disadvantage of dust dispersal during milling; thus, wet milling may be preferable. However, research on the mechanical properties of dental zirconia milled under different conditions and sintered at different temperatures is lacking. PurposeThe purpose of this in vitro study was to evaluate changes in the mechanical properties of zirconia specimens after milling under dry and wet conditions at different sintering temperatures. Material and methodsFour hundred Ø20.0×1.5-mm presintered zirconia specimens were prepared by using a computer-aided design and computer-aided manufacturing (CAD-CAM) system and divided into 8 groups (n=50) based on the sintering (1230, 1330, 1430, and 1530 °C) and milling conditions (dry or wet). The mechanical properties (Vickers hardness, biaxial flexural strength, and fracture toughness) and physical properties (linear shrinkage and density) were examined. The microstructures of the specimens were observed with a scanning electron microscope. The crystal phases of the sintered green bodies were analyzed by using an X-ray diffractometer. The data were analyzed with descriptive statistics and 1-way and 2-way analyses of variance with Tukey HSD tests (α=.05). ResultsThe mechanical properties of all specimens increased with increasing sintering temperature, except for 1530 °C and the dry milling condition. The mechanical properties of the groups fabricated under wet milling conditions were better than those of the groups fabricated under dry milling conditions. Microscopic examination of the structure showed that the porosity decreased with increasing sintering temperature regardless of the milling conditions. ConclusionsHigher sintering temperatures increased the mechanical properties (biaxial flexural strength, Vickers hardness, fracture toughness). However, phase transformation from tetragonal to cubic was observed for dry milled specimens sintered at 1530 °C, with decreased mechanical properties. Specimens fabricated by wet milling exhibited better mechanical properties than those fabricated by dry milling.

Mass-Individualisation – the twenty first century manufacturing paradigm

The forthcoming paradigm of Mass-Individualisation will combine the low-cost advantage of the Mass-Production paradigm with the buyer’s individual need of a specific product. The buyers will initiate the product and its features that fit their explicit taste and individual needs, and the manufacturer will build it at low cost in a local factory, which enables a rapid communication of the factory with the buyer. The realisation of the mass-individualisation paradigm requires innovations in (a) product development, (b) manufacturing system and network design, (c) system operations, and (d) business strategies. New factories will have to be in proximity to the customers who participate in the design of their product, which will have an enormous economic impact on local economies. We elaborate on the research challenges and directions for the realisation of the emerging mass-individualisation paradigm.

Effects of repeated use of tungsten carbide burs on the surface roughness and contact angles of a CAD-CAM PMMA denture base resin

Statement of problemThe surface roughness (Ra) and wettability of complete denture base materials must meet certain clinical requirements. Although computer-aided design and computer-aided manufacturing (CAD-CAM) systems have recently become popular for the fabrication of complete dentures, the effects of the repeated usage of milling burs on the surface properties of CAD-CAM denture base acrylic resins have not yet been fully investigated. PurposeThe purpose of this in vitro study was to evaluate the effects of new and used burs on the Ra and contact angles (wettability) of a CAD-CAM polymethylmethacrylate (PMMA) denture base material. Material and methodsA total of 40 Ø2×10-mm disks were fabricated from 1 brand of CAD-CAM PMMA resin (Polident). Half of the specimens (group N) were milled with a new tungsten carbide bur set, while the other half (group U) was milled with a used tungsten carbide bur set. Moreover, half of the specimens (groups NT and UT) were subjected to thermocycling before Ra and contact angle testing. Ra was tested by using a profilometer, and the surfaces were also examined by scanning electron microscopy (SEM). The contact angle was measured by using the sessile drop method. Data were analyzed with the Kruskal-Wallis and Dunn Pairwise Comparison tests (α=.05). ResultsThe mean contact angle was highest for group U (80 degrees) and lowest for group UT (66 degrees) (P<.05). Ra values were highest for group N (1.3 μm) and lowest for group U (0.93 μm) (P<.05). ConclusionsSpecimens milled with new tungsten carbide burs had lower mean contact angles and higher Ra values than specimens milled with used burs. The contact angles of CAD-CAM PMMA resin specimens milled with used burs decreased significantly after thermocycling. Regardless of whether or not thermocycling was performed, contact angle values decreased as Ra values increased.

Uncertainty and Changeability in Manufacturing Equipment Planning

Increasing time and cost pressure are forcing companies to plan and design their manufacturing systems with fuzzy product data in order to keep pace with shorter and agile product development cycles. This development is accompanied by a multitude of requirements for the planning of the respective manufacturing equipment. Many of these requirements are associated with a high degree of uncertainty and can thus only be specified vaguely in early planning phases, eventually leading to costly, originally unforeseen changes to the specified type of equipment. This consequently underlines the need for a predictive evaluation of uncertainty, or changeability in this context, to enable a more efficient planning approach based on quantified levels of uncertainty. In this paper, the authors therefore present the results of a systematic literature review on the evaluation of changeability in manufacturing systems design with special focus on uncertainty. Most importantly, standardized methods are not available yet; hence, product development as well as project management approaches are frequently adapted to manufacturing systems design. Furthermore, FMEA and fuzzy-logic-based methods are promising techniques for the assessment of uncertainty as a key element of changeability. Concluding, the paper discusses how the findings could support the development of a holistic approach to identify and predictively evaluate uncertainty in order to use it as a decision-making factor for the application of agile planning methods, thus contributing to better decision-making and higher achievement levels of project targets in industrial practice.

A simulated annealing approach for optimizing layout design of reconfigurable manufacturing system based on the workstation properties

The problem studied focuses on facility layout problems (FLP) that arise in reconfigurable manufacturing systems. The goal is to reduce the distance traveled by an automatic guided vehicle (AGV) to move products between several workstations. The proposed solving approach takes into account the empty and loaded travels made by this vehicle as well as the machine's properties (i.e. layout, orientations, shapes of workstations). We use simulated annealing to optimize this problem. The findings demonstrate the impact of the modification of the layout, the orientation, the shape, and the benefits of using the three together. In addition, we study two different ways to optimize the solution: each property independently (i.e. sequentially) or all properties together. Preliminary results show that the sequential method outperforms the latter in terms of distance gain.

The impact of operation, equipment, and material handling flexibility on the design of matrix-structured manufacturing systems

The impact of operation, equipment, and material handling flexibility on the design of matrix-structured manufacturing systems

Product Design for Matrix-Structured Manufacturing Systems

In recent years, the demand for smarter and more customized products has increased. Traditional manufacturing systems are typically designed for mass production, which is not suitable for producing customized products. It requires a new manufacturing system that is flexible, scalable, and reconfigurable, for example, a matrix-structured manufacturing system. As the manufacturing system and product design form a symbiotic relationship, products should also be designed for the new manufacturing system to optimize performance. This paper presents a four-stage methodology to improve the product and product family design targeted production in matrix-structured manufacturing systems. The four stages include a product family analysis, indicator calculations, product optimization, and digital twin-based verification and validation. The proposed methodology is applied in a laboratory case study. The result shows that the improved product design has a significantly higher design efficiency than the original ones. We conclude that the methodology of Design for Matrix-Structured Manufacturing Systems has a holistic view on the product family and can optimize the production efficiency in matrix-structured manufacturing systems.

From automation toward integration of process planning: a state-of-the-art review

The two main objective functions for designing the manufacturing system are, improving the manufacturing system's productivity and production quality. Process planning is an integral part of manufacturing system design. In this work, the study of process plan evolution over the period has been reviewed, keeping in mind the design objectives. Based on the technological advancements, the process plan evolution has been classified into two periods. The first evolution relates to automation, in which efforts are made to automate the manual activities of conventional process plans, which leads to the development of Computer-Aided Process Planning (CAPP). As long as the systems are deterministic with fixed structures and capabilities, CAPP is a good solution. Due to the uncertainty in the market for product demand, the new manufacturing systems are becoming more and more dynamic to handle the product variety demand. In that case, just automation is not enough to achieve the objective functions of system design. Designers have to consider the integration of the manufacturing system life cycle. So the second evolution of the process plan relates to, the consideration of performance indicators defined due to the system integration. For the second evolution, the literature review of the reconfigurable process plan (RPP) is performed considering both automation and integration of the system.

Economic efficiency of automated manufacturing systems design

Systems for the automated planning and design of manufacturing systems have been widely studied and are a promising answer to current challenges arising from shorter product life cycles, high labor costs, and increasingly complex production resources. However, implementing these systems entails substantial investment, and their profitability depends on various factors. One of the major difficulties in implementing automated planning systems in an industrial context has been establishing a suitable database of resource models. This article presents an evaluation method to compare the economic efficiency of manual and automated planning, including resource modeling. It also explores different application scenarios to determine under which preconditions automated planning is advantageous and where the limits of their application lie.

DEVELOPMENT OF AN AUTOMATED DESIGN SYSTEM FOR FLEXIBLE AUTOMATED PRODUCTION

Design of flexible manufacturing systems (FMS) of modern multi-level production is usually carried out on the basis of general rationing when using large recommendations. At the same time, the specifics and features of a particular production are not always taken into account. In such a design, the most important is the experience of the designer, which is not always based on modern methods of optimizing project solutions. Therefore, the problem of creating automated design systems in the development of flexible automated productions (FAP), which use cost equipment with numerical control (CNC) is extremely urgent. The development of automated design systems is based on the ideas of a systematic approach that determine different cycles of the process: design - production preparation - production. Information about the projected object is generated in the process of project development by different groups of users: researchers, designers, designers, technologists, production organizers. A multilevel, cyclical design process requires the use of such a volume of information that cannot be processed without the use of modern mathematical methods and calculated equipment. Therefore, it is extremely important to create automated gap design systems, which are marked by greater versatility, efficiency and possibility of development, improvement and adaptation to the conditions of various enterprises. Such requirements served as the basis for the creation of an automated design system , which allows to take into account a huge amount of information in the automatic cycle during the development of the project. The scientific novelty of the work is the development of an integrated automation system for the design of processing technology and the selection of elements of FMS structures. At the same time, information unity with the system of technological training of production at the level of operation of FMS is ensured.

USING THE SLP METHOD IN THE DESIGN OF FLEXIBLE MANUFACTURING CELLS

Flexible manufacturing systems are becoming increasingly important as customers increasingly want customized products. Also, the trend of the product life cycles to become shorter and shorter causes the proliferation of flexible manufacturing systems. Proper layout is key to making the manufacturing system truly flexible. Novel research and this article show how the Systematic Layout Planning method can be applied to the design of flexible manufacturing systems and, going further, how the design process can be supported by manufacturing process simulation.

Design Methodology and Tools in Factory of the Future

Abstract This paper presents a design method and tool developed to support the skill forming activities in the DigiFoF network (https://www.digifof.eu/). The focus is on training of manufacturing system design skills both as HEI education and vocational training, but preliminary design of new manufacturing systems is also supported (e.g in the development of small business process scenarios). We proposed a model-based methodology for solving of the manufacturing system design problems The methodology and the supporting tool are centred around a less abstract Domain-Specific Modelling Language (DSML). The language is easy to learn due to its few components. A modelling and simulation environment named Digital Production Planner Tool (DPPT) was generated from the metamodel of the DSML. The degree of abstraction used by this tool corresponds well to the intended use in training and preliminary design. Our method incorporates by design the possibility to impose constraints at the modelling language level to limit the modelling space to feasible/possible solutions. The resulting tool enforces these constraints in the use and supports the development of feasible designs even by inexperienced designers. The access to the conceptual model allows the translation of the model to other modelling language like Petri net. This extends the support for the design methodology. The whitepaper presents a use case for the developed method and tool: the design of a chocolate manufacturing line.

Modeling of reconfigurable manufacturing system architecture with geometric machines and in-stage gantries

Reconfigurable Manufacturing Systems (RMSs) are well recognized by their capability to achieve high responsiveness and flexibility and are receiving increasing interest in today’s versatile manufacturing environment. This paper aims to develop methods to study the performance of RMS architecture consisting of machines and in-stage gantries whose time to failure and time to repair follow geometric distributions. A discrete-time Markov chain model is built to perform an exact analysis for two-stage-one-buffer systems. A decomposition method is developed to analyze multi-stage systems. Moreover, both time-dependent failure and operation-dependent failure modes are considered. Numerical studies that compare the calculated production rate and work-in-process to the simulation results demonstrate that the proposed methods can provide accurate results, especially for balanced systems and for systems with a small number of stages. The impact of different parameters (e.g., buffer capacity, machine/gantry reliability) on the production rate of the two models is also studied. Finally, examples on the applications of the models in the manufacturing systems design and operations are presented.

Heuristic-based approach to solve layout design and workers’ assignment problem in the cellular manufacturing system

ABSTRACT The design process of a cellular manufacturing system (CMS) involves well-known NP-hard problems. Being an NP-hard, it is difficult to address these CMS-related problems optimally within a reasonable time. Therefore, this paper proposes a novel heuristic-based two-stage approach to tackle the CMS-related problems. In the first stage, a mathematical model is developed to concurrently solve cell formation and workers’ assignment problems (CFWAP). The worker’s selection is determined by their performance in operating a machine for a specific part, measured by the defect rate resulting from assigning the worker to a machine. The model’s objective is to minimize the weighted sum of the total inter-cell, intra-cell movements, operation, and defect costs. In the second stage, based on the output of the mathematical model in the first stage, a heuristic algorithm is developed to solve the problem related to the layout design of the cellular manufacturing system (LDCMS). The actual dimensions of machines and the aisle distances between them are considered in LDCMS to find out the best possible allocation of the machines and cells within the entire system. A comparison is conducted between numerical examples from the literature to show the efficiency and the validation of this two-stage heuristic approach. The results show that the proposed method can optimally tackle the aforementioned CMS-related problems within a reasonable time. To the best of our knowledge, this is the first study that integrates the CFWAP with LDCMS, considering all these practical and manufacturing features. Finally, it should be noted that the proposed approach has been applied as a real case study for a central workshop on die manufacturing for a food stove company in Egypt. The results depict a significant reduction in the company’s total associated costs by achieving up to 23% savings from applying the proposed method.