Papers by Cezarina Afteni
MATEC web of conferences, 2022
The optimal management of the manufacturing processes is achieved through a set of optimal decisi... more The optimal management of the manufacturing processes is achieved through a set of optimal decisions, which must be made for choosing the best way to follow, every time we find ourselves in a point from which several potential manufacturing paths start. A dedicated method, namely the Holistic Optimization Method has been already developed in this purpose, and validated in a number of studies based on artificial and real instances databases. In the current papers that approach the optimal management of the manufacturing processes, in order to estimate the consequences of a decision, are used known methods, such as: NN modeling, big data analysis, statistics, etc. In all these cases, the database size plays an essential role in terms of estimation quality. The present study aims to prove the feasibility of applying the Holistic Optimization Method when the decision-maker does not dispose of a consistent database. This can be a significant advantage relative to the other methods. The study is performed using an artificially generated instances database in the case of a turning process, and the results obtained are promising.
IOP Conference Series: Materials Science and Engineering, 2020
In the manufacturing industry, globalization, shorter life cycles of products and changing custom... more In the manufacturing industry, globalization, shorter life cycles of products and changing customer needs, leads to high competitive pressure on companies. In addition to product quality and variety, flexibility, shorter processing times, and high-level compliance with delivery times have become essential factors for market success through efficient, efficacious and continually manufacturing processes optimization. To be successful in a highly competitive global production environment, a company must be able to deliver products that customers request at the requested time. In this paper is developed a novel method of structural identification of the bearing manufacturing process. This method allows the structuring of its activities, at all levels involved (order acceptance, production planning, product design, processes planning, and product processing), by elaborating the tree of the specific activities. The relations between the manufacturing process stages and related information...
Annals of ”Dunarea de Jos” University of Galati, Fascicle V, Technologies in machine building, 2018
IOP conference series, Mar 1, 2022
In the global market, the supply chain performances have a significant impact on the company's bu... more In the global market, the supply chain performances have a significant impact on the company's business strategy. The quality requirements that must be followed by suppliers require permanent monitoring of processes of design, development, production, installation and service of products through audits qualified based on supply chain management. This paper presents an analysis of the supplier qualification process including the main phases as follows: evaluation, monitoring and auditing of suppliers in supply chain management. Internal quality audits and/or suppliers are one of the key instruments for ensuring sustainability and performance in supply chain management. Auditing of suppliers is a core component of the modern management of suppliers, with the help of which the customer can analyze precisely relevant processes to existing or potential suppliers. Supplier audits help both commercial partners to increase the transparency of the supply chain and also simplify supplier selection, evaluation, monitoring and development. The suppliers must meet the highest quality standards for products and processes. The main purpose of this paper is to give a general view of the supplier qualification process which involves the steps from initial identification until the inclusion of the supplier in the Approved Supplier List (LST). This list should be managed in such way that a complete traceability is assured. Following the proposed qualification diagram the customer can obtain an image about the status of one supplier, can also identify the weak points considering the evaluation, monitoring and audit class.
Annals of ”Dunarea de Jos” University of Galati, Fascicle V, Technologies in machine building, 2022
Energy consumption is different for various technological processes used in manufacturing (cuttin... more Energy consumption is different for various technological processes used in manufacturing (cutting, plastic deformation, sintering, welding, etc.) and nowadays is becoming a more and more important issue to be considered when planning certain manufacturing processes. Related to this, when releasing a quotation for a given product request coming for the market, it is important to have a tool enabling to evaluate the estimated energy consumption that will be required. This paper proposes a method to predict the consumption of energy in the welding process depending on the same main parameters of the process. The method is based on causal identification and on the NN modelling technique. Method application is sampled in the case of a real database including information concerning pipes welding. The method proves to be fast and delivers results of reasonable precision.
Lecture Notes in Mechanical Engineering, 2017
Advanced manufacturing technologies are based on-time-delivery principles. The customer requireme... more Advanced manufacturing technologies are based on-time-delivery principles. The customer requirements regarding quality, cost and delivery terms become more and more important , both for supplier and sub-supplier. Taking into account these considerations, all companies started the implementation of some new strategies and technologies based on continuous improvement principle. One of these is hard turning, as a cost efficient alternative to grinding. The technology is analyzed in the case of a bearing component, as a new process step versus the existing grinding process. Experimental tests were performed in order to describe the advantages of this technology. Cubic Boron Nitride grades (CBN) are used for cutting. The main influence of this technology in process flow is analyzed from different approaches. Experimental results were analyzed in terms of the ring surface quality, roughness and profile, and also on process time and production cost.
IOP Conference Series: Materials Science and Engineering, 2017
Annals of ”Dunarea de Jos” University of Galati, Fascicle V, Technologies in machine building, 2022
In the actual economic environment, it is more and more important for people to be aware of their... more In the actual economic environment, it is more and more important for people to be aware of their impact on environmental aspects, consumption of natural resources and usage of resources several times by recycling and reuse at the initial intended usage or changing the place of usage in opposition to the principle of owning, using and then throwing away. The increasing of waste quantities are the direct consequences of consumption that exceeds real needs and, at the same time, alters the state of the environment as the main provider of resources. In the coming years, approaches of the products’ design and built must be focused to allow for the continued reuse of resources. The introduction of the circular economy is a challenge to the linear economy approach to resource production and consumption. The circular economy is an economy that produces zero waste. The circular economy concept is not so new. European and world decision-making communities have been circulating for years the ...
The hydroforming process is a nonconventional method for producing sheet metal deep drawing piece... more The hydroforming process is a nonconventional method for producing sheet metal deep drawing pieces, under the direct or indirect action of a high pressure fluid on the inner or outer side of work piece wall. This process it`s known since the 1900s and it has continuously developed, being today a field of research in the universities from country and abroad. The design of the hydroforming process can be done according to empirical, analytical and numerical methods to obtain high precision of the hydroforming piece and to ensure a large deformation of the material. The hydroforming parts can be used in various fields such as the automotive, aircraft and aerospace industries, having relatively low costs compared to parts obtained by other types of processing such as rolling, forging or stamping. The paper gives an overview regarding the sheet metal hydroforming processes, methods and the equipment used, as well as the process limits and defects that can occur during hydroforming.
IOP Conference Series: Materials Science and Engineering
The management of MTO-based production involves multiple decisions needing to be taken. They conc... more The management of MTO-based production involves multiple decisions needing to be taken. They concern all stages of manufacturing activityorder acceptance, products design, processes planning and jobs scheduling. Such decision consists in selecting, at a given moment, the most suitable alternative of the potential ones. This means that comparative assessment of potential alternatives is required. The usual method underpinning the comparative assessment supposes the direct, separate evaluation of each alternative, before decision making. In this paper we suggest a different approach in performing the comparative assessment, based on alternatives rankings, considered as the most relevant information about them. More specific, this means that rankings are assigned to potential alternatives, by referring them to the cases of already performed manufacturing activities, recorded as past instances database, after ranking criteria such as cost, time span, consumed energy etc. Thus, the selection decision results by comparing potential alternatives rankings. For finding the ranking of a given alternative, a solution to assess the difference between instances is needed, at first. Then, after iteratively defining instances neighborhoods from database and modeling them by multiple nonlinear regression, its ranking is determined. Here, we propose an expression for the distance-function together with an algorithm for actually finding the ranking of the analyzed alternative. A numerical simulation for the instance-based comparative assessment, with the help of an instances artificial database is also presented.
Transactions of Famena, 2021
In manufacturing system management, the decisions are currently made on the base of 'what if' ana... more In manufacturing system management, the decisions are currently made on the base of 'what if' analysis. Here, the suitability of the model structure based on which a model of the activity will be built is crucial and it refers to multiple conditionality imposed in practice. Starting from this, finding the most suitable model structure is critical and represents a notable challenge. The paper deals with the building of suitable structures for a manufacturing system model by data-driven causal modelling. For this purpose, the manufacturing system is described by nominal jobs that it could involve and is identified by an original algorithm for processing the dataset of previous instances. The proposed causal modelling is applied in two case studies, whereby the first case study uses a dataset of artificial instances and the second case study uses a dataset of industrial instances. The causal modelling results prove its good potential for implementation in the industrial environment, with a very wide range of possible applications, while the obtained performance has been found to be good.
International Journal of Modeling and Optimization
This paper concerns a new approach of the optimization problem, intending to turn into profit the... more This paper concerns a new approach of the optimization problem, intending to turn into profit the last evolutions from IT domain. On the base of this approach, both new concept (the holistic optimization), and method ("zoom & pick") for its implementation it in manufacturing process optimization were developed. According to the new concept, the optimization problem gets a new structure, which includes not only the optimal solution finding, but also the optimal formalization of the problem as well as the tooling for assessing the position of potential solutions relative to the optimal one. The method for holistic optimization successively addresses the optimized object at different levels of its description. The main application domain is the manufacturing process from "Make to Order" environment, which is difficult to optimize because of dealing with a wide range of products.
MATEC Web of Conferences
In industry, process planning has a major impact on manufacturing performance. This paper propose... more In industry, process planning has a major impact on manufacturing performance. This paper proposes a method aiming to increase the efficiency in process planning, more specific in selecting the set of plans with high potential of performance. The method works on the base of processes classification after their energy efficiency. It is applied for processes grouped in the same utility area, and involves the definition of energy classes. A case study, having as purpose to prove the feasibility and effectiveness of the proposed method is also presented. Energy labelling may further become an efficient tool enabling the manufacturing process optimization from energetic point of view.
International Journal of Modeling and Optimization
In this study is present a systematic analysis of already published works on formulating and solv... more In this study is present a systematic analysis of already published works on formulating and solving optimization problems concerning manufacturing process. Analysis it was performed on two levels, namely: planning and scheduling of manufacturing process. They were considered: type of optimization (mono-criterion or multi-criteria); objective function (the energy consumption, the manufacturing costs, the productivity, the manufactured surface roughness); methods of solve (Genetic Algorithms GA, Particle Swarm Optimization PSO technique, Artificial Neural Networks ANN). The main purpose of this study it is to substantiate a new approach to optimization problems. The proposed approach is of holistic type, based on integrated process planning and scheduling (IPPS) and defines new performance indicators, to be adapted to market current requirements.
International Journal of Modeling and Optimization
The conventional approach is not the best choice for optimizing the manufacturing process, becaus... more The conventional approach is not the best choice for optimizing the manufacturing process, because of its specific structure, and of the specific definition of the optimization problem in its case. During last years, the authors of this paper have developed the concept of holistic optimization and a method for its application in manufacturing process optimization. The method works on the base of two procedures, aiming the causal identification and the comparative assessment of the manufacturing jobs. This paper presents a validation of these procedures by applying them in the case of estimating the manufacturing cost of roller bearings. The case study used a database extracted from the industrial environment. Clusters of condition-variables being the most appropriate for evaluating the cost are determined, at first. Then, neighborhoods of the interrogated cases are extracted from the database and the proximity function is identified. The estimated ranking (hence the manufacturing cost) of the interrogated case is found on this base, eventually.
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Papers by Cezarina Afteni