Papers by Keyword: Tool Life

Abstract: The objective of this study is to evaluate the wear progression of cryogenically treated and untreated tungsten carbide inserts during face milling of Grey Cast Iron which is a commonly used material in machine tool beds and automotive components due to low cost, high vibration damping capability, and easiness of manufacturing. Commercially available uncoated Tungsten Carbide insert with around 6% Cobalt (Co) content were selected for the study and flank wear and nose wear were taken as the performance evaluation criteria. The results show that the cryogenically treated samples have better wear resistance than the untreated inserts which could be ascribed to the martensitic phase transformation of Co from α-Co (FCC) to ε-Co (HCP) during the cryogenic treatment.

Abstract: In this paper are presented and analyzed a series of problems that are appearing during the CFRP machining. Due to their properties, the composite materials began to replace traditional materials (ferrous and non-ferrous) in a lot of industries leading out the development of new methods of machining or adaptation of the classic. Unlike traditional material, drilling in CFRP is more difficult due to inhomogeneity of the material, its high hardness but also due to lack of knowledge relating to how these materials behave. This paper investigates different types of tool wears as corner wear, welding, crater wear that are appearing in drilling operation due to the highly abrasive nature of the carbon fibers. Also, here is presented an evaluation that refers to the machined hole quality and describe defects as delamination, pull outs, fibers projections, pyrolysis and shape errors. The main goal of this paper is to verify the current status of technique in CFRP drilling in order to develop and produce a new drill geometry in a cooperation between the Technical University of Cluj-Napoca and the cutting tool company Gühring KG.

Abstract: The research in the last decade regarding their cutting machinability have highlighted the insufficiency of the data for establishing of the optimum cutting processing conditions and the optimum cutting regime. The purpose of this article is the optimization of the tool life and the cutting speed at the drilling of the stainless steels in terms of the maximum productivity. A nonlinear programming mathematical model to maximize the productivity at the drilling of a stainless steel is developed in this paper. The optimum cutting tool life and the associated cutting tool speed are obtained by solving the proposed mathematical model. The use of this productivity model allows greater accuracy in the prediction of the productivity for the drilling of a certain stainless steel and getting the optimum tool life and the optimum cutting speed for the maximum productivity. The obtained results can be used in production activity, in order to increase the productivity of the stainless steels machining. Finally the paper suggests new research directions for the specialists interested in this field.

Abstract: In the specialized literature the cost of the machining process has been analyzed using a number of approaches and varying degrees of simplification to determine the optimum tool life and the tool speed. The accuracy of prediction is dependent on the degree of sophistication of the model. The purpose of this paper is the optimization of the cutting tool life and the cutting speed at the drilling of the stainless steels in terms of the minimum machining cost. A more comprehensive nonlinear programming model to minimize the total cost at the drilling of a stainless steel is developed in this paper. The optimum tool life and the associated tool speed are obtained by solving this model. The results can be taken into consideration in the educational studies and in the theoretical technical research. They can be implemented in the manufacturing activity.

Abstract: The paper presents the contribution in methodology of production processes of difficulty to cut materials particularly in optimization method of Duplex Stainless Steels (DSS). In this work, Design of Experiment (DOE) is used to examine turning experimental data. The DOE, based on the Taguchi method with orthogonal array L₉ and signal-to-noise ratio are used. The optimal values of the technological cutting parameters with coated carbide tool point are searched. ANOVA analysis was performed to determine the signification of machining parameters. The significance of various cutting parameters on tool life have been proven. The results at optimum cutting condition are predicted using estimated values. The study was performed within a production facility during the machining of electric motor parts and deep-well pumps.

Abstract: The paper examines the influence of cutting parameters, namely cutting speed and feed rate on the tool life in machining process of cylindrical billets made from a Duplex Stainless Steel (DSS). Two optimization methods is presents, one based on the Taguchi design of the experiment with orthogonal array L₉ and signal-to-noise ratio (S/N) and the second based on the dynamic programming approach with modified Dijkstra's algorithm have been used to find optimal levels of the control parameters. ANOVA was performed to determine the significance of the input variables. A predictive mathematical model has been developed through a regression analysis to study the response. The results at optimum cutting conditions are predicted using estimated values. Finally, the features, the merits and the limitations of the presented optimization approaches were discussed.

Abstract: This paper presents a novel concept for extending the life of the tools that are used in the milling process of carbon-fiber-reinforced plastic (CFRP) composites. Three types of tools were compared in milling tests; tool I: an uncoated tungsten carbide (WC-Co) tool, tool II: a polycrystalline diamond (PCD) tool, and tool III: a combination tool comprising a PCD layer surface with a thickness of 100 μm and a WC-Co substrate flank surface. The measurement of changes in cutting forces over cutting distance revealed that tool III had a better (tool) life performance than the other tools. Additionally, observation of changes in the edge profiles of the tools revealed that the effective edge sharpness of tool III remains constant during the milling tests. The difference between the wear rates of the PCD rake and WC-Co flank surfaces in tool III maintained a constant effective sharpness during the milling process, and it extended the tool life. Based on our findings, we concluded that using the difference between the wear rates of rake and flank surfaces is an effective technique for tool life extension in the milling process of CFRP laminates.

Abstract: In this paper, driven rotary cutting of maraging steel was carried out and the influence on tool wear of difference cutting conditions was investigated. As cutting conditions, different coolant conditions, cutting speeds, circumferential velocity ratios, tool inclination angles, tool rotation directions and normal rake angles were tested. We found that as the coolant quantity decreased and cutting speed increased, the width of flank wear increased. It was also found that the circumferential velocity ratio, tool inclination angle, tool rotation direction and normal rake angle have optimal conditions that decrease wear. Optimal conditions were chosen, and a tool life test was carried out. As a result, driven rotary cutting was achieved with 11 or more times the tool life of conventional turning.

Abstract: Heat treatment is a process often used to improve product performance by increasing the strength of material or other desirable characteristics. Silicon nitride (Si₃N₄) tool insert is known for its attractive properties including high fracture toughness, strength and wear resistance at elevated temperatures. Heat treating these inserts by post-sintering them for 15 minutes at 600°C using conventional heating and hybrid microwave energy has prolonged tool life by 11-21% and 48-94% respectively. Machining was performed on a T6061 Aluminium alloy rod for tool life analysis at three different cutting speeds; 215, 314 and 393 m/min. Cost analysis is performed on these post-sintered Si₃N₄ inserts and found that there are economical benefits in the tooling cost when compared with the untreated Si₃N₄ inserts.

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.