Miron Zapciu

Research concerning optimum cutting parameters according with tool path strategy for finishing procedures

Optimization of cutting parameters in NC milling needs to be studied because of its influence on machining time and cost. Today, any CAM software offers many tool path strategies to milling free form geometries. However, the users must have the know-how to choose the strategies according to geometry complexity, cutting tool geometry and its contact on the machined surface. Choosing the right strategy with the right cutting parameter is a rather difficult task to do on the machine tool. In this paper we try to take into account the influence of the toolpath over the surface quality for finishing operation. The main goal is to establish a direct link between machining parameters and toolpath in order to obtain the same surface quality for different trajectories. The first step consist in making a series of experiments for standards toolpaths (which can be found in any CAM software) like one-way, zig-zag, spiral from outside to inside, zig-zag at 45 dgr on a milling center. Based on the results, a correction coefficient for the feed rate was established.

The Link between Lean and Green Manufacturing - A Way to Reach Sustainable Development

Today, manufacturing products in a sustainable way is increasingly becoming essential in the eyes of investors, authorities and customers. Failure leads to fines, penalties, and customers choosing to go to the competition. Success, on the other hand, can save money, helps build a reputation, attracts investment, spurs innovation, secures loyal customers and brings in repeat business. Taking into account the sustainable manufacturing is not just longer a caprice for the business.During the end of the twentieth century and into the twenty-first century two types of manufacturing systems that emphasize waste minimization have emerged: Lean and Green manufacturing. Despite the importance of Green manufacturing to the environmental problem, many companies are still skeptical about the business benefits. In the same time, however, a good many of them see the business benefits of Lean manufacturing. Several research efforts summarized in the literature review indicate how both systems share many of the same best practices to reduce their respective wastes. Yet, these two systems tend to operate independently.The aim of this research is to explore and to determine how the Lean manufacturing can include Green manufacturing system components in their overall strategy to reduce waste.

The milling process monitoring using 3D envelope method

This paper proposes a method to vibration analysis in order to on-line monitoring of milling process quality. Adapting envelope analysis to characterize the milling tool materials is an important contribution to the qualitative and quantitative characterization of milling capacity and a step by modeling the three-dimensional cutting process. An experimental protocol was designed and developed for the acquisition, processing and analyzing three-dimensional signal. The vibration envelope analysis is proposed to detect the cutting capacity of the tool with the optimization application of cutting parameters. The research is focused on Hilbert transform optimization to evaluate the dynamic behavior of the machine/ tool/workpiece.

Analyse du comportement dynamique d’une broche de machine-outils

L’apparition de vibrations, ou bien des regimes instables, est induite par l’interaction dynamique du processus de coupe avec le systeme elastique de la machine-outil dans differentes conditions de travail. L’objectif de ce travail est de developper un modele dynamique applique au processus de fraisage pour realiser la surveillance du processus, l’analyse et l’optimisation des conditions de coupe lors du contact outil/piece/machine. Pour mettre en place ce protocole et atteindre les connaissances approfondies des phenomenes dynamiques nous effectuons une etude de ceux-ci divisee en deux parties : la machine et le processus de coupe. Une analyse dynamique detaillee de la machine est obligatoire avant de modeliser les phenomenes vibratoires presents lors de la coupe.

Production Systems Flow Modelling Using Decomposition Method and Required Buffers

This paper aims to provide an introduction to the analytical modelling and the discrete-events simulation for a manufacturing system. A general method of constructing a Markov chain and the simulation with discrete events using Delmia Quest software, are presented. In the present paper, those interested can find a real case study: modelling and simulation of the headrest support manufacturing line. The scientific contribution of this paper consists in the development of a theoretical model implemented in a real case study. The theoretical model estimates the production rate of the line and then, using this model we can establish how many parts in the buffers are required in order to achieve a production rate of X parts per minute. In the first phase, the manufacturing line is analyzed, then the Markov chains for subsystems with two machines and a buffer are constructed. As the Markov chains need more time to provide solutions in queues theory, they can be used only for small production lines. To find the production rate for all the system, it is necessary to apply the Markov chains and the decomposition method. Those methods are implemented in the C/C++ programming. To validate the analytical model, the discrete-event simulation with Delmia Quest software is used. The article presents some comparisons between modelling with Markov chains and simulation with Delmia Quest software and provides a method of optimization of the buffers for the case study.

Beyond Target Costing: Manufacturing Cost Policy Deployment for New Products

The purpose of this paper is to present a method to quantify the costs of potential losses from production processes for new products to prioritize improvement projects based on the target cost and provide data and information for feasibility studies of continuous improvement projects. The specificity of the manufacturing cost policy deployment for new products is to identify the percentage of cost of future production phases which does not add value from a customer perspective, dynamically throughout the product life cycle. The percentage of non-value added cost is based on loss of each manufacturing process and is determined scientifically based on data and facts. Using the proposed method helps manufacturing companies in the acceptance of certain orders which at first glance are unprofitable. Moreover, the proposed method will help develop scenarios for continuous cost reduction after starting production through continuous improvement of productivity and quality required. The empirical results are based on the study during a year and a half in the automotive company, using action research methodology.

Behaviour Analysis of Hexapod Structure for Integrated Design

In this research work, the analysis of a parallel structure, hexapod type, was studied from the rigidity point of view. The modelling of the structure and the assembly were designed in SolidWorks one of the most used software for the design in the construction of machine tools, automotive and aeronautics field. The modal, the static analysis, forces and moment loading, were performed with ANSYS programme by finite element method, for each of the three studied positions of the structure.

Evaluation and Improvement of the Spindle Thermal Transfer

The main source of heat generation in a spindle is the friction torque in the ball bearing angular contact. The thermal and structural behavior of both spindle shaft/housing and bearings is characterized by the thermal expansion and the rate of heat generation depending on the operating speed. To evaluate the temperature distribution and its effects on the axial and radial deformations a simulation procedure is required. This paper is a presentation of the numerical models performed using the (ANSYS) commercial finite element software in order to assess the thermal behavior effect on the spindle nose axial deformation. Two numerical models were designed and simulated; the first model is a classic spindle in which heat dissipation of the bearings is removed by conduction and convection with the environment and with the second model, the generated heat is removed by water cooling circuits to improve the temperature distribution and axial deformation in the housing and spindle shaft.

3D Parametric Modeling for Complex Parts Generation

The complex parts, like block engine or inside panel door, represent a real challenge for 3D modeling with modern parametric 3D CAD systems if we intend to reuse the modeling for future modifications. The complexity of the part generates a large number of parameters and parametrical dependencies that is difficult to manage and even difficult to change for modifying the part, often, for big changes, making it easier to remodeling the part from the beginning. In this paper is presented a new method of parametric and hierarchical 3D modeling that allows easy future modifications of the part. This paper also presents the implementation of this new method in Catia V5 and the validation for a number of CAD models.

Torsor Evaluation of the Tooth during the Milling Process

Analysis of the torsor evolution in milling process is very important for optimization of the cutting process to achieve high quality of manufacturing, productivity and cost. Our study is based on the analysis of the Mx, My and Mz moments‘ evolution at the tooth tip of the tool during the milling process. A complex experiemntal setup is designed and realized to obtain a three-dimensional response of the mechanical actions. During the tests, the complete torsor of mechanical actions generated by the cutting process were measured by six components dynamometer (forces and moments according to each direction). In this paper a method for tool position determination in milling process is presented, with purpose to transport and evaluate the moments to the tooth tip of the milling cutter.