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Temperature of cutting is a very important indicator of the cutting process. High specific pressures and high temperatures in the narrow cutting zone result in a drop of hardness of the tool material, the intensification of the abrasion and deformation of the cutting elements, losing the cutting abilities, and finally the failure of the cutting tool. The aim of this paper is to calculate the temperature fields using the existing numerical models for the simulation of thermodynamic processes on the wedge of the cutting tool (based on the finite element method). A special accent is given to the numerical calculation of temperatures in the conditions of continuous and discontinuous turning for specific cutting conditions (processing regime, tool geometry and thermo-mechanical characteristics of the tool materials and workpiece materials) using different simulation models. The Third Wave AdvantEdge software package was used for the simulation of orthogonal turning, and some of the results of the calculations of the temperature fields were compared with the results of experimental measurements.

Dross height is an important cut quality characteristic in plasma jet cutting process. It can be defined as molten metal blown from the cutting zone and localized on the bottom of the metal sheet. In each plasma jet cutting process, it is important to obtain dross free cuts. Aluminium is as material very present in shipbuilding and metal industry and because of that very usually cut by plasma jet. Because of high heat and electrical conductivity of aluminium, plasma jet cutting is followed by insecurity about process parameters settings that lead to optimal cut quality characteristics. The aim of this paper is to develop a fuzzy logic model that predicts the influence of variable process parameters on dross height in plasma jet cutting of aluminium alloy 5083. Experiments were performed according to Taguchi L27 orthogonal array by varying cutting speed, arc current and cutting height as input process parameters. Fuzzy logic model was defined using Mamdani inference system. This model was used to investigate effects of variable process parameters on dross height response. In order to analyse interaction effects of plasma jet cutting process parameters on dross formation 3D surface and contour plots were generated. The analysis revealed that the cutting speed has the most significant effect followed by arc current and cutting height. Obtained results of this research indicate that artificial intelligence technique, fuzzy logic, can be effectively used for modelling and prediction of dross formation in plasma jet cutting process of aluminium alloy.

Mechanical tests were performed on samples prepared from the body and the neck of bottles made of seamless tube, steel 34CrMo4. Plastic material flow curves were taken from tensile tests on samples which were made from tubes and finished bottles. Deformation hardening intensity is calculated, and propensity towards brittle fracture is estimated on the basis of the ratio of total elongation and elongation at maximum load. Compared to the samples of quenched and tempered bottle body, quenched and tempered bottle neck samples indicate that characteristics of strength are almost unchanged with an increase in the minimum strain at the destruction from 12,8% to 15,1%. It was concluded that the results of the plastic material flow can serve as a preliminary indication of anomalies that could contribute to unsatisfactory results of the burst test.

In this paper Artificial Neural Network (ANN) model was developed for prediction of kerf width in plasma jet metal cutting process. Process parameters whose influence was analyzed are cutting height, cutting speed and arc current. An L18 (21x37) Taguchi orthogonal array experiment was conducted on aluminium sheet of 3 mm thickness. Using the experimental data a feed – forward backpropagation artificial neural network model was developed. After the prediction accuracy of the developed model was verified, the model was used to generate plots that show influence of process parameters and their interactions on analzyed kerf width and to get conlusions about process parameters values that lead to minimal kerf width.

U okviru ovog rada prikazani su rezultati ispitivanja utjecaja promjenljivih parametara obrade: koraka i broja okretaja na površinsku hrapavost legure aluminija 6005A-T6, pri CNC istosmjernoj i suprotnosmjernoj obradi glodanjem s alatima različitih dimenzija i od različitih materijala (Ø6 HSS, Ø6 VHM i Ø10 VHM). Navedene su karakteristike i klasifikacija aluminijuskih legura. Dana je definicija hrapavosti površine kod završnog glodanja (end milling) i navedeni parametri koji na nju utječu. Zaključeno je da je korak najutjecajniji parametar na hrapavost, dok je najmanja hrapavost postignuta glodanjem (up milling). Jednadžbe korelacije dale su dobro predviđanje površinske hrapavosti u slučaju obrade VHM glodalom Ø10. Rezultati eksperimenta poslužit će kao ulaz u model za upravljanje ulaznim parametrima procesa obrade putem regeneriranja NC koda u cilju poboljšanja kvalitete obrađene površine., The paper presents the research results of the impact of variable machining parameters: feed and spindle speed on surface roughness of Aluminium alloy 6005-T6, at CNC in the up and down milling with tools of different dimensions and different materials (Ø6 HSS, Ø6 VHM and Ø10 VHM). The properties and classification of Aluminium alloys are cited. The definition of surface roughness at end milling is given and parameters that affect it are specified. It was concluded that the feed is the parameter that has the most influence on surface roughens, while the lowest roughness is achieved by up milling. Correlation equations have provided good prediction of surface roughness in the case of machining of VHM by cutter Ø10. The results of the experiment will serve as an input into the model for control of input parameters of the machining process by regeneration of NC code for the purpose of quality improvement of machined surface.

U ovom je radu predstavljena metodologija višekriterijske optimizacije karakteristika kvalitete reza kod CO2 laserskog rezanja AISI 304 nehrđajućeg čelika (korozijski postojanog čelika). Za predviđanje karakteristika kvalitete reza kao što su hrapavost površine reza, širina reza i zona utjecaja topline, kreirani su matematički modeli pomoću umjetnih neuronskih mreža. Eksperiment laserskog rezanja je planiran i izveden prema Taguchijevom L27 ortogonalnom nizu, a eksperimentalni podaci su korišteni za treniranje umjetnih neuronskih mreža pomoću Levenberg-Marquardtovog algoritma. Matematički modeli umjetnih neuronskih mreža su kreirani uzimajući u obzir snagu lasera, brzinu rezanja, tlak pomoćnog plina i položaj fokusa kao ulazne parametre. Problem višekriterijske optimizacije je formuliran koristeći metodu težinskih koeficijenata, pri čemu su težinski koeficijenti, na osnovu kojih je izvršena kombinacija karakteristika kvaliteta reza u jednu ciljnu funkciju, određeni metodom analitičkog hijerarhijskog procesa., In this paper, multi-objective optimization of the cut quality characteristics in CO2 laser cutting of AISI 304 stainless steel was discussed. Three mathematical models for the prediction of cut quality characteristics such as surface roughness, kerf width and heat affected zone were developed using the artificial neural networks (ANNs). The laser cutting experiment was planned and conducted according to the Taguchi’s L27 orthogonal array and the experimental data were used to train single hidden layer ANNs using the Levenberg-Marquardt algorithm. The ANN mathematical models were developed considering laser power, cutting speed, assist gas pressure, and focus position as the input parameters. Multi-objective optimization problem was formulated using the weighting sum method in which the weighting factors that are used to combine cut quality characteristics into the single objective function were determined using the analytic hierarchy process method.

Glavne karakteristike površine obrađene abrazivnim mlazom vode su razlike u hrapavosti površine na vrhu i na dnu reza i pojava zakrivljenih linija-brazgotina koje su karakteristične za sve procese obrade s koncentriranim tokom velike energije. Zakrivljenost ovih linija je posljedica zaostajanja mlaza. Zaostajanje mlaza je uzrok grešaka pri rezanju radijusa i oštrih kutova. Parametri obrade imaju značajan utjecaj na ovu pojavu. Iz tog razloga nužno je poznavati i definirati utjecaj parametara obrade na ovu pojavu. Cilj ovog rada je istražiti utjecaj parametara obrade na zaostajanje mlaza, odnosno geometriju reza. Uzorci od AISI 304 obrađeni su abrazivnim mlazom vode različitim posmičnim brzinama, radnim tlakovima i protocima abraziva. Zaostajanje mlaza mjereno je na 10 mjernih mjesta preko dubine reza. Na temelju tih rezultata, formiran je odnos između zaostajanja mlaza i parametara obrade., The main characteristics of the surface machined with the abrasive water jet are the differences in surface roughness at the top and bottom of the cut and the appearance of curved lines-striations, which are characteristic for all machining processes with the concentrated stream of high energy. The curvature of these lines is the consequence of jet lagging. Jet lagging is the cause of errors in cutting of radius and sharp corners. The machining parameters have a great influence on this phenomenon. Therefore, it is necessary to know and to define the influence of machining parameters on this phenomenon. The aim of this paper is to investigate the effect of machining parameters on the jet lagging, i.e. cut front geometry. The specimens of AISI 304 were machined by the abrasive water jet under varying traverse speeds, operating pressures and abrasive mass flow rates. The jet lagging was measured at ten monitoring points by the depth of cut. Based on these results, the relationship between the jet lagging and machining parameters has been formed.