Eduard Niţu

Functional Modeling of an Assembly Line Supplied in Synchronous

The present paper is part of a broader study of the authors, consisting of modeling and simulating several production systems. Functional modeling of a workstation supplied by various methods was carried out and presented in the paper [. This paper presents the functional modeling of an assembly line composed of 4 workstations with manual activities, designed to make 4 types of products (multi-product line). The supply with parts of the line is made with kitting system. The novelty of this study is the use of IDEF0 functional modeling method to describe the functioning of the assembly line in which the supply method is synchronous. The functional model developed had allowed to identify and to design the kitting and picking circuits, as for the highlighting of the traces followed by the components to the workstations, depending on their type of supply. This model can be extended and used to other assembly lines supplied in synchronous.

Friction Stir Welding of three dissimilar aluminium alloy used in aeronautics industry

Friction Stir Welding (FSW) is an innovative solid-state joining process. This process was, in first time, develop to join the similar aluminum plates but now the technology can be used to weld a large area of materials similar or dissimilar. Taking these into account FSW process, for dissimilar materials are increasingly required, more than traditional arc welding, in industrial environment. More than that FSW is used in aeronautics industry because of very good result and very good weldability between aluminum alloy used at building of airplanes, where the body of airplane are 20% aluminum alloy and this percent can be increaser in future. In this paper is presented an experimental study which includes welding three dissimilar aluminum alloy, with different properties, used in aeronautics industry, this materials are: AA 2024, AA6061 and AA7075. After welding with different parameters, the welding join and welding process will be analyzed considering process temperature, process vertical force, and roughnessof welding seams, visual aspect and microhardness.

Numerical Simulation of Friction Stir Welding (FSW) Process Based on ABAQUS Environment

. Simulation of the FSW process is a complex issue, as it implies interactions between thermal and mechanical phenomena and the quality of the welding depends on many factors. In order to reduce the time of the experimental tests, which can be long and expensive, numerical simulation of the FSW process has been tried during the last ten years. However, there still remain aspects that cannot be completely simulated. In this paper the authors present the steps of the numerical simulation using the finite elements method, in order to evaluate the boundary conditions of the model and the geometry of the tools by using the Arbitrary Lagrangian Eulerian (ALE) adaptive mesh controls.

Numerical Simulation of Friction Stir Spot Welding

Friction Stir Spot Welding (FSSW) is a solid state joining process that relies on frictional heating and plastic deformation realized at the interaction between a non-consumable welding tool that rotates on the contact surfaces of the workpieces. Friction Stir Spot Welding (FSSW) is an evolving technique that has received considerable attention from automotive industries to replace electric resistance spot welding, which shows poor weldability for advanced high-strength steels as well as aluminium alloys. Because of the interest shown by the industry towards this process, an attempt to optimize it is imperative. But the experiments are often time consuming and costly. To overcome these problems, numerical analysis has frequently been used in the last years. The purpose of this paper is to develop a three-dimensional fully coupled thermal-stress finite element (FE) model of FSSW process for thin aluminium alloy Al 6061-T6. Numerical simulation being helpful for better understanding and observation of the influence of input parameters on the resulting phenomena. It is described the algorithm and are presented the activities needed to be performed in order to develop a valid numerical model for FSSW. The validation of the numerical model being achieved by comparing the resulted temperatures from the numerical simulation with the experimentally determined temperatures for the same material

The Analysis of Performances of an Assembly Line in Strike-Zone Supply Method Managed with Kanban and Conwip

The present paper is part of a larger study of the authors, which consists in the analysis of performances of several production systems. On a multiproduct assembly line supplied in Strike-Zone, are made researches on the influence of the method of production flow management, the method of launching in production and by varying the clients demand size on several performance indicators. The assembly line has mainly manual activities, divided in 5 workstations. The line produces two types of similar products. Using dynamic simulation (Arena software) that mimics the lines functioning mode, different experimental conditions are created, determined by the variation of the above mentioned parameters, following the evolution of the performance indicators: average work in process, cost per unit, systems reactivity to client demand and throughput. The obtained results were interpreted and structured, in a manner to help the process managers to take adequate decisions considering the wanted objectives.

Numerical Simulation of Friction Stir Welding of Aluminum Alloys: A Brief Review

Friction Stir Welding (FSW) is the latest innovative and most complex process which is widely applied to the welding of lightweight alloys, such as aluminum and magnesium alloys, and most recently, titanium alloys, copper alloys, steels and super-alloys. Friction stir welding is a highly complex process comprising several highly coupled physical phenomena. The experiments are often time consuming and costly. To overcome these problems, numerical analysis has frequently been used in the last ten years. In this paper is presented a brief review of scientific papers in recent years on numerical simulation of Friction Stir Welding of aluminum alloys. The main elements analyzed by FSW simulation, and briefly in this paper are: temperature and residual stress distribution; work tool geometry (size and shape of the pin); distribution of equivalent plastic deformation; main areas resulted after welding; distribution of microstructure (grain size); parameters and optimization of the FSW process.

Friction Stir Welding of Composite Materials with Metallic Matrix: A Brief Review

Composite materials with metallic matrix are increasingly require more than traditional materials metallic, being lighter, more reliable and with their superior properties like: rigidity, tensile strength, flexural strength, fatigue strength, modulus of elasticity, hardness, etc. Due to these advantages, above mentioned, this process has largely penetrated industrial environment. Despite these advantages, there are restrictions on their combination through traditional fusion welding methods so that was passed at the solid-state welding processes, respectively at Friction Stir Welding (FSW). Our researches presents in this brief review: some general ideas about composite materials with metallic matrix and Friction Stir Welding process, appearance and benefits, basic information about the process and composite materials welded by this process, shows the current state of the research with respect to behaviour macrostructure, microstructure, microhardness, tensile properties and defects of the welded joint between composite materials with metallic matrix.

Analysis of Intermittent Metal Forming with Planetary Rollers by Numerical Simulation

Abstract. Processing profiles through form tapping process with planetary rollers is used in industry, especially in the automotive industry. Even though this process exists for several decades, few studies dealing with this topic were published. The main objective of this paper was to determine the influence of the two process parameters on three important values which influence the quality of profiles: the rolling force, the state of stresses in the deformed material and on the rolling time. The material used was carbon steel AISI 1015.

The Analysis of Performances of an Assembly Line in Synchronous Supply Managed with Kanban and Conwip Methods

The present paper is part of a larger study of the authors, which consists in the analysis of performances of several production systems. The researches presented in this paper analyze the influence of the method of production flow management, the method of launching in production and the size of demand from the client on several performance indicators of a multiproduct assembly line supplied on stock. The assembly line is multiproduct type (are assembled 2 types of products that resemble as configuration and technology) and it has 5 workstations with mainly manual activities, that are supplied with parts using a synchronous method. The performance indicators considered were: average work in process, cost per unit, systems reactivity to client demand and throughput, their values being obtained by simulating the functioning of the assembly line in different experimental conditions, determined by the variation of the above mentioned parameters, using ARENA software. The synthesis of the results and their interpretation allow the process managers to take adequate decisions depending on targeted objectives.

Influence of Production Flow Management Methods on an Assembly Line Supplied on Stock

The present paper is a continuation of a larger study of the authors, which consists of an analysis on the performances of several production systems. In this paper it is analyzed the influences of the method of managing the flows, the method of production programing and the clients demand on performance indicators of a multiproduct assembly line supplied on stock. The assembly line is designed to produce two types of similar products and is made of 5 workstations with mainly manual activities, which are supplied with parts on a stock based method. The performance indicators chosen for analysis were: average work in process, cost per unit, systems reactivity to client demand and throughput. The values of these indicators were obtained by simulating the assembly lines functioning in different experimental conditions, determined of the variation of above mentioned variables, by using ARENA software. The obtained results were interpreted and structured, in a manner to help the process managers to take adequate decisions considering the wanted objectives.