Papers by Keyword: Machining

Abstract: The cooling systems on machine tools are particularly important; these have a positive influence on the cutting operation and the quality of machined surface. A particular importance represent finding an optimal correlation between the lubricant and coolant used, the material to be processed, processing method and the cutting regime. A high temperature in the working area over a certain value allowable can be harmful in terms of both the resulted surface quality and repercussions on the life of the cutting tool. The parameters of the cooling-lubricating fluid flow can be influenced by the nature of the fluid or fluids, or the nozzle geometry used, which generally has a convergent-divergent geometry in order to achieve a better dispersion of the coolant/lubricant on the area to be machined.

Abstract: Precision machining is currently intensively studied. Production of quality products fast, and precise with paying attention on environmental issues, brings many factors which counteracts to ensure these aspects. Is very crucial to know system machine – tool – workpiece and is necessary to characterize all elements and limitations connected with this system. Choice of suitable cutting tools is very important part of production process. Acquisition cost of tools in serial production is only below 10 % but in medium production can be up to 50 % of production cost. Know the characteristic of the tool is very important to ensure effective machining process and economic stability of whole production process. The article is focused on clarification of basic indicators, which should be used to more effective and more economical handling with cutting tools.

Abstract: Calculation of the machining parameters is one of the basic routine operations carried out before initializing the work and technological operations on a machine tool. Basis for calculating these parameters is obtained from the technical documentation in the form of rules, tables, catalogues and company literature. It can be concluded that this is a routine activity which represents a significant proportion of the activities performed before actual production of the product. It is exactly the routine activities that are possible to underpin and process well with the help of computers and appropriate application equipment. This contribution describes the design and implementation of a knowledge based system of calculation of the processing and operational machining parameters with the possibility of parameter correction with regard to specific technological equipment. The result is the obtaining of an optimal machine setting for machined range of products with a consideration for the production efficiency, durability of the cutting tool and the possibility of reusing the archived operational parameters.

Abstract: In order to obtain a better understanding of the effects of an internal broaching operation on the resulting component geometry, investigations were carried out. The investigations were carried out on sliding sleeves made of case hardening steel SAE 5115 (German grade 16MnCrS5). The cutting speed was varied. The results indicate that the arrangement of teeth on the scope of the tool has a significant influence on the resulting component geometry. Furthermore the results show that also the cutting speed has a significant influence on the resulting component geometry, in particular due to the resulting process temperatures.

Abstract: In modern machining processes, there are continuous cost pressures and high quality expectations in the product. Hence, it is required to explore the techniques that can reduce the cost and also increase the quality of the product. In the present work, machining performance of AISI 316L SS is assessed by the performing turning operation under nano cutting environment. Experiments have been carried out by plain turning of 48mm diameter and 600mm long rod of AISI 316L stainless steel on all geared lathe at different cutting velocities and feeds under wet machining with and without Carbon nano Tubes (CNT) inclusions using carbide inserts. The effect of cutting speed, feed rate, depth of cut on tool chip interface temperature and surface roughness are analysed using Taguchi method. Furthermore, using analysis of variance method, significant contributions of process parameters have been determined. Experimental results reveal that feed rate and cutting speed are the dominant variables on responses.

Abstract: Over the years, with the increasing development of engineering materials, the emergence of new composites, fiber metal laminated, biomaterials, metal alloys etc., and with demand for products less expensive, less polluting and more efficient, the manufacturing engineering also needs to develop to be able to process these new materials. Materials and tool geometries, intelligent mechanisms, modular machines, also follow this setting. To that end, this work comes to raise the main parameters that influence in the hole quality surface of finished product. Were used two polymeric materials, ultra high molecular weight polyethylene (UHMW-PE) and polytetrafluoroethylene (PTFE), two feed rates, three rotations and three tool geometries, allowing to identify which of these parameters have greater influence on the thrust force and the characteristics of the finished product and dimensional deviation.

Abstract: This work presents a study on the effect of Minimum Quantity Lubricant of Al203 nanoparticle with Sodium Dodecylbenzene Sulfonate, SDBS on surface roughness during turning of Mild Steel under constant machining parameters. Surfactant, SDBS in the nanolubricant creates stability of the particles in the base fluid. The experiments were conducted under dry, MQL with pure nanolubricant, and MQL with nanolubricant and additional SDBS. The experimental results showed that MQL nanolubricant with additional SDBS improves the surface roughness compared to dry cutting.

Abstract: The increase of world requirements for improved products joined to growing competition between companies in the global market makes the same seek processes that ensure lower costs allied to high productivity and high quality product. Therefore, the great industrial and technological development has been increased the search for machining processes that promote, for example, high performance as regards the chip removal, less tool wear, failure and reduced impact on the environment. Regarding nickel-based superalloys, they have an extremely important role in the aeronautical and automotive industries among others. The nickel-based superalloy studied is the Nimonic 80A, hard machine material that has high mechanical strength and corrosion resistance on higher temperatures. The objective of this report is to study the influence of the application of cutting fluids in turning and the machining parameters in order to achieve high performance and optimization of machining this alloy. This one was machined using various machining parameters: cutting speed, feed rate, cutting depth, Minimum Quantity fluid (MQF), and Fluid abundant. After turning chip samples were obtained, was measured the surface roughness, volume of chip removed, cutting length and macro structural, some analyzes were performed and of lifetime of the tools were used in order to detect possible wear, as well as, microstructural observation of the chips by optical microscopy, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS).On this report, we can observe the behavior of the materials and tools in the two cooling conditions used, and also, the impacts of the parameter variations in the surface finish, on the structure of the material and performance of the tools in respect chip removal regarding volume removed and machined length. Application by MQF was promising, but there is an abundant beyond the traditional application.

Abstract: Molding techniques and manufacturing of components consisting of fibre reinforced polymers are mostly controlled processes. However, finishing of such materials can even today still be seen as a very challenging and not completely controlled process, which often has a non-satisfying machining quality as result. This paper deals with different topics in the field of machining FRP. On the one hand, it deals with ideas for possible evaluation mechanisms in order to classify the resulting machining quality of FRP when machining with a cutting edge. Referring to this, a framework for the definition of an international standard in measuring machining quality on FRP parts is presented. On the other hand, a possible assistance system with the aim to improve the demanding cutting process as well as a tool life experiment, are investigated. The results of these practical experiments are presented and evaluated.

Abstract: In numerical approaches for high speed machining, the rheological behavior of machined materials is usually described by a Johnson Cook law. However, studies have shown that dynamic recrystallization phenomena appear during machining in the tool/chip interface. The Johnson Cook constitutive law does not include such phenomena. Thus, specific rheological models based on metallurgy are introduced to consider these dynamic recrystallization phenomena. Two empirical models proposed by Kim et al. (2003) and Lurdos (2008) are investigated in machining modeling. A two-dimensional finite element model of orthogonal cutting, using an Arbitrary Lagrangian-Eulerian (ALE) formulation, is developed with the Abaqus/explicit software. Specific rheological models are implemented in the calculation code thanks to a subroutine. This finite element model can then predict chip formation, interfacial temperatures, chip-tool contact length, cutting forces and chip thickness with also and especially the recrystallized area. New specific experiments on an orthogonal cutting test bench are conducted on AISI 1045 steel specimens with an uncoated carbide tool. Many tests are performed and results are focused on total chip thicknesses and recrystallized chip thicknesses. Finally, compared to numerical results got with a Johnson Cook law, numerical results obtained using specific rheological models to take into account dynamic recrystallization phenomena are very close to experimental results. This work shows also the influence of rheological behavior laws on predicted results in the modeling of high speed modeling.