Paweł Twardowski

Investigation of wear and tool life of coated carbide and cubic boron nitride cutting tools in high speed milling

The objective of the investigation was analysis of the wear of milling cutters made of sintered carbide and of boron nitride. The article presents the life period of the cutting edges and describes industrial conditions of the applicability of tools made of the materials under investigation. Tests have been performed on modern toroidal and ball-end mill cutters. The study has been performed within a production facility in the technology of high speed machining of 55NiCrMoV6 and X153CrMoV12 hardened steel. The analysed cutting speed is a parameter which significantly influences the intensity of heat generated in the cutting zone. Due to the wear characteristics, two areas of applicability of the analysed tools have been distinguished. For vc  ≤ 300 m/min, sintered carbide edges are recommended; for vc  > 500 m/min, boron nitride edges. For 300 ≤ vc  ≤ 500 m/min, a transition area has been observed. It has been proved that the application of sintered carbide edges is not economically justified above certain cutting speed.

Surface roughness analysis of hardened steel after high-speed milling.

The work refers to analysis of various factors affecting surface roughness after end milling of hardened steel in high-speed milling (HSM) conditions. Investigations of milling parameters (cutting speed v(c) , axial depth of cut a(p) ) and the process dynamics that influence machined surface roughness were presented, and a surface roughness model, including cutter displacements, was elaborated. The work also involved analysis of surface profile charts from the point of view of vibrations and cutting force components. The research showed that theoretic surface roughness resulting from the kinematic-geometric projection of cutting edge in the workpiece is significantly different from the reality. The dominant factor in the research was not feed per tooth f(z) (according to the theoretical model) but dynamical phenomena and feed per revolution f.

Hybrid numerical-analytical model for force prediction in end milling

Numerical technique finite element method (FEM) was used by researchers dealing with machining at the turn of the 1970s and 1980s. Due to the high complexity of the problem, the cutting analysis was limited to the orthogonal model. This treatment was to bring the problem to a plane strain, to facilitate the modeling of geometry and to limit the number of degrees of freedom. Despite such far-reaching simplifications, modeling of the machining process in FEM software presents many problems, which even today is dominated by two-dimensional models in scientific publications [3, 6, 8]. Orthogonal models, although seemingly simple, provide researchers with a unique insight into the cutting zone, but are still often insufficient to solve problems in the industry. The paper presents a hybrid numerical-analytical model for prediction of forces during end milling of 42CrMo4 steel (40HM) [4, 5]. In the model, the FEM simulation was used to determine the correct specific cutting force for a given tool geometry in orthogonal cutting. These data, in turn, using an analytical model based on the Altintas mechanical model [1], will be converted into forces acting in the machine tool system for the variable uncut chip thickness during milling. This approach to the problem can be applied at the design stage of monolithic milling cutters prior to prototyping.

Diagnosis of edge condition based on force measurement during milling of composites

Abstract The present paper presents comparative results of the forecasting of a cutting tool wear with the application of different methods of diagnostic deduction based on the measurement of cutting force components. The research was carried out during the milling of the Duralcan F3S.10S aluminum-ceramic composite. Prediction of the toolwear was based on one variable, two variables regression Multilayer Perceptron(MLP)and Radial Basis Function(RBF)neural networks. Forecasting the condition of the cutting tool on the basis of cutting forces has yielded very satisfactory results.

Comparison of various tool wear prediction methods during end milling of metal matrix composite

Abstract In this paper, the problem of tool wear prediction during milling of hard-to-cut metal matrix composite Duralcan™ was presented. The conducted research involved the measurements of acceleration of vibrations during milling with constant cutting conditions, and evaluation of the flank wear. Subsequently, the analysis of vibrations in time and frequency domain, as well as the correlation of the obtained measures with the tool wear values were conducted. The validation of tool wear diagnosis in relation to selected diagnostic measures was carried out with the use of one variable and two variables regression models, as well as with the application of artificial neural networks (ANN). The comparative analysis of the obtained results enable.

Evaluating the Reliability of Groove Turning for Piston Rings in Combustion Engines with the Use of Neural Networks

Abstract The article describes a method of evaluating the reliability of groove turning for piston rings in combustion engines. Parameters representing the roughness of a machined surface, Ra and Rz, were selected for use in evaluation. At present, evaluation of surface roughness is performed manually by operators and recorded on measurement sheets. The authors studied a method for evaluation of the surface roughness parameters Ra and Rz using multi-layered perceptron with error back-propagation (MLP) and Kohonen neural networks. Many neural network models were developed, and the best of them were chosen on the basis of the effectiveness of measurement evaluation. Experiments were carried out on real data from a production company, obtained from several machine tools. In this way it becomes possible to assess machines in terms of the reliability evaluation of turning.

Optimization of cutting parameters for the longitudinal turning of combustion engines’ pistons

Głównym celem optymalizacji procesów skrawania jest poprawa efektów ekonomicznych oraz technologicznych obróbki. Z przeglądu literatury wynika, że problematyka ta dotyczy głównie skracania czasu i obniżania kosztów produkcji, wydłużania trwałości ostrza, podnoszenia jakości obrobionej powierzchni, a także minimalizacji drgań układu obrabiarka–uchwyt–przedmiot–narzędzie [1÷5]. Jedną z metod mających na celu poprawę efektów ekonomicznych skrawania jest optymalizacja ze względu na trwałość ostrza [6]. Podejście to umożliwia wyznaczenie ekonomicznej prędkości skrawania vce, odpowiadającej wygenerowaniu minimalnych kosztów jednostkowych Kj zabiegu, oraz wydajnościowej prędkości skrawania vcw, zapewniającej maksymalizację wydajności obróbki W. Aby zrealizować to zadanie, niezbędne jest przeprowadzenie badań trwałościowych ostrzy skrawających i wyznaczenie wykładnika potęgowego s występującego we wzorze Taylora:

Machining Characteristics of Direct Laser Deposited Tungsten Carbide

Machinability can be defined as the relative susceptibility of the work material to the decohesion phenomenon and chip formation, during cutting and grinding. This feature depends on work and tool’s material physic-chemical properties and condition, method of machining, as well as cutting conditions [1]. Therefore, there is no unique and unambiguous meaning to the term machinability. This feature, can be described by many various indicators. Each one of them carries out a wide variety of operations, each with a different criteria of machinability. A material may have good machinability by one criterion, but poor machinability by another [2].

HSM Machining Stability During Hardened Steels Milling Process

In this paper HSM analysis of milling hardened steels is presented. All cutting parameters under process stability are described as well. The process stability is showing from point of view of self-excited chatter of machined system, assessed basis on signals of the chatter accelerations and components of resultant force.© 2008 ASME