Authors:Marin Gostimirović, Dragan Rodić, Milenko Sekulić, Andjelko Aleksić

Abstract

Plasma arc cutting (PAC) is an unconventional process widely used in manufacturing of heavy plate products. This work reports on the research results of machining quality of the workpiece in the plasma arc cutting on the low carbon low alloy steel. An experimental investigation of the characteristics of machining accuracy and surface integrity was carried out for basic machining parameters (cutting speed, arc current, arc voltage, plasma gas pressure, stand-off distance and nozzle diameter). The kerf geometry was determined with three accuracy parameters (top kerf width, bottom kerf width and kerf taper angle). The parameters of deviation present due to plasma curvature were defined by drag and pitch of drag line. The surface roughness was determined with two main roughness parameters through scanning the surface topography (roughness average and maximum height of the profile). The surface properties were determined over microstructure in heat affected zone (HAZ). The results show an acceptable machining quality of the PAC, so that this process is an excellent choice for fast and efficient material removal. However, the plasma arc cutting is not suitable for the final machining because of the metallurgical variations in the HAZ.

Key words: plasma arc cutting; machining accuracy; surface topography; heat affected zone

DOI: 10.24867/ATM-2020-1-001

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Authors:Isiaka Oluwole Oladele, Samson Oluwagbenga Adelani and Joseph Ajibade Omotoyinbo

Abstract

In this study, 8011A aluminum alloy was subjected to artificial ageing and joined by tungsten inert gas (TIG) welding process. The effect of welding process on the mechanical (hardness, tensile, impact) properties, corrosion resistance and microstructure of the artificially aged and welded joints were investigated. The sample was divided into pre weld heat treated and as received samples. The pre weld heat treated sample was subjected to solution treatment at 500°C, soaking for 1 hour, and quench in water before artificial ageing was carried out at 180 °C with holding time of 8 hours. Both the pre heat treated and the as received samples were welded using tungsten inert gas (TIG) welding process. It was observed from the results, that the pre weld heat treatment adopted improved the mechanical properties and corrosion resistance ofthe weldments in some of the properties examined. In comparison with the welded samples, the hardness, tensile yield strength and corrosion resistance of the pre weld heat treated samples were significantly improved. There was an improvement of 11% in hardness, 9% in yield strength and 92 % in corrosion resistance when immersed in 3.5 wt% NaCl solution.

Key words: Artificial aging; TIG welding; Pre weld heat treated; Mechanical properties; Microstructure; Corrosion behavior.

DOI: 10.24867/ATM-2020-1-002

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Authors: Nikola Vorkapić, Saša Živanović, Nikola Slavković, Zoran Dimić, Branko Kokotović

Abstract

This paper describes the configuration of a 3-axis vertical CNC machine tool for rapid prototyping with one rotary and two translational axes. The machine works in a polar-cylindrical coordinate system. The structure of the machine is C’OXZ. The virtual machine model is configured in the PTC Creo software environment. After configuring the virtual machine, the simulation of the CLFbased was performed in the mentioned software environments, and then the verification according to the G-code program in the Vericut software environment was performed. Programming and control of the configured prototype machine are realized in the LinuxCNC software environment, which is based on the PC platform. Also, in this paper, digital twin of machine realized in a python software environment is shown. The presented results show the proper functioning of the whole system.

Key words: CAD/CAM, CNC machine tool, virtual machine, LinuxCNC , digital twin;

DOI: 10.24867/ATM-2020-1-003

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Authors: Saša Ranđelović, Mladomir MIlutinović, Vladislav Blagojević, Srđan Mladenović, Dejan Tanikić

Abstract

In the industrial processes of injection molding, one of the basic requirements is a uniform temperature filed within workpiece and the mold cavities. In the case of simple geometry of workpiece and mold with single cavity achieving a uniform temperature field is not a critical issue. However, if one deals with parts of complex geometries, multi-cavity molds and asymmetric layout of different forms in the mold additional analyses of the runner and cooling system are necessary in order to obtain the required quality and accuracy of end the products. Disposition and dimensions of both runners and cooling channels are directly related to the geometry of finished parts and material properties. In that sense, virtual models and numerical simulations of injection molding processes based on the finite element method are very effective tool which enable accurate prediction of potential problems and significant reduction of trial and error procedure. In this paper, FEM software package Moldex3D was employed for simulation and analyses of injection molding process in which pipe fittings Ø75/45o and Ø75/90o are produced using a mold with two asymmetric cavities.

Key words: Injection molding, viscosity, cooling system, mold design

DOI: 10.24867/ATM-2020-1-004

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Authors:Miloš Pjević, Mihajlo Popović, Ljubodrag Tanović

Abstract

The parts obtained by sheet metal forming technology can be classified as a percentage in the most common parts of assemblies and sub-mechanisms of mechanisms. The basic problem that occurs when making sheet metal parts using bending process, is the elastic return. The elastic return coefficient that can be used as a correction coefficient in the bending process is necessary to be determine for the used material, as well as for the processing conditions. All this led to high cost of the processing tool. On the other hand, rapid tooling constantly increasing its present in the processing presses. One of the biggest advantages of the rapid tooling is reduction of the cost and processing time of the final product. In this paper, the experimental identification of the elastic return coefficient for three different materials (Al-alloy, non-alloy steel and stainless steel) was performed, as well applicability of rapid tooling on sheet metal bending. The experiments covered a range of bending angles from 65° to 135°. It has been found that depending on the type of material and the bending angle, the elastic return coefficient can vary considerably. It also turned out that its value is significantly influenced by the geometry of the punch. All elements made using additive technology, successfully performed work tasks without the occurrence of destruction.

Key words: Rapid tooling; Sheet metal; Bending; Springback

DOI: 10.24867/ATM-2020-1-005

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