Morphology of Near- and Semispherical Melted Chips after the Grinding Processes Using Sol-Gel Abrasives Based on SEM-Imaging and Analysis

Selected issues related to SEM-imaging and image analysis of spherical melted chips formed during the grinding process are presented and discussed. The general characteristics of this specific group of machining products are given. Chip formation phenomena, as well as their overall morphology, are presented using selected examples of near- and semispherical melted chips occurring singly or concentrated in clusters on the grinding wheel surface after the machining process. Observation of the spherical melted chips and acquisition of their images were carried out for grinding wheel active surfaces with microcrystalline sintered corundum abrasive grains SG™ after the internal cylindrical grinding process of a 100Cr6 steel and Titanium Grade 2® alloy by use of a scanning electron microscope, JEOL JSM-5500LV. Analysis of the obtained SEM micrographs was carried out by Image-Pro® Plus 5.0 software to determine the selected geometrical parameters describing the morphological features of the assessed chips

Current quality of life and its determinants among opiate-dependent individuals five years after starting methadone treatment

This study explores the current QoL of opiate-dependent individuals who started outpatient methadone treatment at least 5 years ago and assesses the influence of demographic, psychosocial, drug and health-related variables on individuals' QoL. Participants (n = 159) were interviewed about their current QoL, psychological distress and severity of drug-related problems, using the Lancashire Quality of Life Profile, the Brief Symptom Inventory and the Addiction Severity Index. Potential determinants of QoL were assessed in a multiple linear regression analysis. Five years after the start of methadone treatment, opiate-dependent individuals report low QoL scores on various domains. No association was found between drug-related variables and QoL, but a significant negative impact of psychological distress was identified. Severity of psychological distress, taking medication for psychological problems and the inability to change one's living situation were associated with lower QoL. Having at least one good friend and a structured daily activity had a significant, positive impact on QoL. Opiate-dependent individuals' QoL is mainly determined by their psychological well-being and a number of psychosocial variables. These findings highlight the importance of a holistic approach to treatment and support in methadone maintenance treatment, which goes beyond fixing the negative physical consequences of opiate dependence

CNC machine setup

W artykule przedstawiono zagadnienie ustawiania maszyn sterowanych numerycznie. Opisano ręczne i automatyczne metody pomiarowe, których celem jest wyznaczenie punktu(ów) zera przedmiotu obrabianego oraz określenie wymiarów narzędzi obróbkowych. Zaproponowano definicje podstawowych pojęć związanych z ustawianiem maszyn CNC oraz przedstawiono ideę określania korekcji narzędzi. Zaproponowano podejście do ustawiania maszyn sterowanych numerycznie, które przekłada się na uzyskiwaną dokładność wymiarowo-kształtową wykonywanych części.The paper presents problems connected with CNC machines setup, mainly describes manual and automated measuring techniques for zero point and tool offsets setting. The paper defines and systematizes the basic concepts, shows zero point transformation idea and suggests correct setup techniques

Symulacja numeryczna i badania eksperymentalne procesu frezowania stopu tytanu Ti6Al4V

This paper is focused on the finite element analysis of machining of Ti6Al4V titanium alloy in a nonorthogonal (3D) face milling process. The study was conducted for face milling with the cutting speed of 80 m/min, depth of cut of 1 mm, cutting width of 10 mm and different feed rates. The FEM simulations include the cutting force components and average maximum cutting temperatures. The simulation results were compared with experimental data obtained for similar milling process configuration. It was found that the kind of FEM constitutive model influences the force and temperature values. In this case the cutting force has a better match with experimental data when using the JC model. On the other hand, a good fitting for both feed and passive forces was achieved for the PL model. Additionally, a very good fitting for the cutting temperature using PL FEM model was obtained. It was also found that the feed rate has a significant effect on the average interface temperature and can be modelled by using FEM material models presented in the article.W pracy prowadzono analizę wyników symulacji procesu frezowania walcowo-czołowego stopu tytanu Ti6Al4V, w układzie nieortogonalnym (3D) z zastosowaniem metody elementów skończonych. W procesie frezowania płaskiego stosowano prędkość skrawania 80 m/min, głębokość skrawania 1 mm, szerokość skrawania 10 mm, dla różnych wartości posuwów. Przy użyciu MES określono wartości składowych sił skrawania oraz maksymalną wartość temperatury skrawania. Walidację wyników symulacyjnych i badań eksperymentalnych prowadzono dla takich samych wartości warunków obróbki. Stwierdzono, że rodzaj konstytutywnego modelu MES ma wpływ na wartości siły i temperatury skrawania. W tym ujęciu dobrą zgodność danych symulacji normalnych i eksperymentalnych, dla przypadku składowej głównej siły skrawania, uzyskano przy zastosowaniu modelu JC. Natomiast lepsze dopasowanie dla składowej posuwowej i odporowej (pasywnej) uzyskano dla modelu PL. Dodatkowo dobre dopasowanie wyniku symulacji i eksperymentu, dla temperatury skrawania, uzyskano także dla modelu MES typu PL. Stwierdzono, że posuw ma znaczny wpływ na wartość średniej temperatury skrawania. Modelowanie tych oddziaływań można realizować, stosując modele materiałowe MES przedstawione w pracy

Analysis of mechanical characteristics of face milling process of Ti6AI4V alloy using experimental and simulation data

This paper presents experimental and 3D FEM simulation results obtained for the Johnson-Cook material constitutive model and variable cutting conditions. Face milling tests were carried out using a Ti6Al4V titanium alloy as the workpiece and coated carbide indexable inserts. CAD models of the cutting tool insert and the face milling head were generated and implemented into FEM package used. The machining conditions were selected based on real production data from aerospace sector. In particular, changes of power and specific cutting energy were analyzed in terms of the rotation angle of the milling head and the ratio of the uncut chip thickness against the cutting edge radius

Influence of Cutting Conditions on Temperature Distribution in Face Milling of Inconel 718 Nickel-Chromium Alloy

This paper presents 3D FEM simulation results obtained for the milling operations on a nickel-chromium alloy (Inconel 718) using the Johnson-Cook material constitutive model and variable cutting conditions. Face milling tests were carried out using silicon-aluminum-oxygen-nitrogen (SiAlON) ceramic cutting tools inserts. The machining conditions were selected based on real production data (cutting speed of vc=750 and 800 m/min, feed of f=0.1, 0.125 and 0.15 mm/t, depth of cut of ap=1, 1.5 and 2 mm). The FEM simulations include the maximum and average values of the cutting temperature. They were compared with experimental data obtained by using the high speed infra-red camera

Evaluation of the cutting force components and the surface roughness in the milling process of micro-and nanocrystalline titanium

Nanocristalline pure titanium in comparison to inicrocrystalline titanium is characterized by better mechanical properties which influence its wider usability. The aim of the research was to evaluate whether the grain size of pure titanium (micro- and nanocrystalline) has influence on the cutting force components and the surface roughness in the milling process. Models of cutting force components for both materials were prepared and differences between the results were examined. The feed rate effect on selected parameters of surface roughness after milling of micro- and nanocrystalline pure titanium was determined

Analiza oddziaływania modelu narzędzia na symulację numeryczną MES procesu skrawania z dużą prędkością (HSM)

The finite element method has been extensively used for the simulation of manufacturing processes and especially machining. In this paper, finite element models of high speed machining are presented. More specifically, orthogonal and oblique cutting models are presented, where the geometrical and material properties of the cutting tool are investigated. Orthogonal models pertain to the simulation of cutting with three different CBN tool types. Chip formation, cutting forces and temperatures are compared for each model, at the same cutting conditions. Additionally, 3D models are presented, where the back rake angle of the cutting tool is varied. From the results it may be concluded that 3D models provide more realistic results but they are computationally more demanding than 2D models. Finite element modelling of high speed machining can provide data for the process that would be either difficult or in some cases even impossible to obtain through extensive experimental work.W artykule określono oddziaływanie geometrii narzędzia na wyniki symulacji numerycznej skrawania z dużą prędkością. Przeprowadzono symulację numeryczną dla skrawania ortogonalnego 2D, dla trzech modeli narzędzi z CBN o różnej geometrii. Porównano podział modeli numerycznych narzędzi na elementy skończone oraz przedstawiono analizę procesu kształtowania wióra, wartości składowych siły skrawania, temperaturę w strefie skrawania oraz odkształcenie plastyczne w warstwie wierzchniej dla wybranych ich geometrii. Przeprowadzono również proces symulacji dla modelu skośnego 3D dla różnych wartości kąta pochylenia krawędzi skrawającej. Wyniki symulacji pozwoliły stwierdzić, że zastosowanie modeli 3D lepiej odzwierciedla rzeczywisty proces. Stawia jednak większe wymagania w zakresie obliczeń niż przy użyciu modeli 2D. Symulacja MES obróbki z dużą prędkością pozwoliła uzyskać wyniki, które mogą być trudne lub w niektórych przypadkach niemożliwe do uzyskania w ramach badań eksperymentalnych