Papers by Keyword: Milling

Abstract: This study focuses on the effect of cutting fluid on sample surface integrity and tool wear in milling additively manufactured Inconel 738LC. Sample surface integrity and tool wear characterization was undertaken using scanning electron microscopy, backscatter electron microscopy, energy dispersive spectroscopy, laser scanning confocal microscopy, ultra-depth of field digital microscope system and digital display hardness tester. Compared with dry milling, wet milling not only provides an entirely different result on surface morphology, but also shows less surface plastic deformation, and smaller surface roughness. In addition, the tool wear mechanisms of wet milling are found to be different compared to dry milling.

Abstract: The synthesis and characterization of the Ba_0.6Sr_0.4Fe_12-3xZn_2xTi_xO₁₉ microwave material with x = 0, 0.2, 0.4, and 0.6 has been successfully carried out. Samples were processed with the solid reaction method through milling at seven hundred revolutions per minute for five hours. X-ray diffraction was used to characterize the phase formation and crystal structure. Scanning electron microscopy was used to see the shape and size of particles, while the vibrating sample magnetometer was used to measure magnetic quantities, which are: the coercivity field and magnetic saturation. All samples have a hexagonal structure, for samples x = 0 and 0.2 have a single phase, while for samples x = 0.4 and 0.6 other phases are detected. The shape of the particles are heterogeneous, with size ranging from 10-25 μm. All samples were not saturated even until the external magnetic field reaches 1 T. As the value of x increases, the magnetization will decrease. Samples substituted by Zn and Ti (x ≠ 0) have higher coercivity field values when compared to sample without substitution (x = 0).

Abstract: Modern methods of machining of bed slideways with the required parameters of accuracy and quality of the processed surfaces are considered in order to increase productivity in the treatment of the surface of machine stands. To improve productivity, the finishing sanding operation has been replaced with finishing milling to ensure the required roughness, flatness and parallelism. The method of replacement of technological operations as exemplified by processing of a bed made of gray cast iron of grade “СЧ-20” is studied. The priority method of increasing the productivity of the processing of machine slideways of metal-cutting equipment, based on the use of cutting ceramics during the processing of the bed as a final technological operation, is determined. Based on the microstructural characteristics of oxide-carbide cutting ceramics, a uniform method of equipping cutters with cutting inserts with equal lifespan is used to increase productivity and achieve the required surface finish. This method of the milling cutter layout allows for longer life and provides the required margin of tool accuracy as well as allows predicting premature wear of the cutting tool. The results of the work are the identification of the patterns of influence of structural parameters of cutting ceramics on the quality of machine slideways of metal-cutting equipment in the selective formation of instrumentation. Studies have shown that the quality of machining depends on the microstructure characteristics of each insert used in the machining process when using interchangeable multi-sided oxide carbide ceramic inserts. The increase in productivity and quality of machining is achieved by monitoring the microstructure of the cutting oxide-carbide ceramics.

Abstract: One of the most significant factors in machining process or metal cutting is the cutting tool performance. The rapid wear rate of cutting tools and cutting forces expend due to high cutting temperature is a critical problem to be solved in high-speed machining process, milling. Near-dry machining such as minimum quantity lubrication (MQL) is regarded as one of the solutions to solve this problem. However, the function of MQL in milling process is still uncertain so far which prevents MQL from widely being utilized in this specific machining process. In this paper, the mechanism of cutting tool performance such as tool wear and cutting forces in MQL assisted milling is investigated more comprehensively and the results are compared in three different cutting conditions which is dry cutting, wet cutting (flooding) and MQL. The MQL applicator is constructed from a household grade low-cost 3D printing technique. The chips surface of chips formation in each cutting condition is also observed using Scanning Electron Microscopy (SEM) machine. It is found out that wet cutting (flooding) is the best cutting performance compare to MQL and dry cutting. However, it can also be said that wet cutting and MQL produced almost the same value of tool wear and cutting forces as there is negligible differences in average tool wear and cutting forces between them based on the experiment conducted.

Abstract: The paper presents the results of experimental studies of strontium hexa-ferrite average particle size and structural characteristics changes during milling process. Coarse strontium hexaferrite was milled in beater mill, without and with electromagnetic effect. Electromagnetic effect was produced by constant and alternating gradient magnetic fields with mutually perpendicular induction lines. Particle sizes were measured by microscopic methods, and structural characteristics were calculated by processing of X-ray diffractograms. Diffraction studies showed that during milling process, both with and without electromagnetic effect, the most intensive changes of coherent scattering region (CSR) sizes, dislocation densities and relative deformation of particulate material occur at earlier stage of milling. At this stage the speed of average particle size decrease is maximal. At later stage both average particle size and structural characteristic changes correlate and have asymptotic character.

Abstract: In order to control the temperature during milling process of aluminum alloys and keeping as minimum as possible, the choice of the cutting parameters and their optimization is very important, both for the tool wear but also for the surface quality of machined surface. The main purpose of this paper is to find the optimum values of the milling parameters (rotational speed and depth of cut) so that the minimum value for the temperature to be obtained. Using adequate experimental conditions with contact measurements techniques (thermocouple K-type) carried out on the some types of aluminum alloys and the appropriate statistical instruments, the most influencing cutting parameters and their values on the cutting temperature can be found. The results are presented both analytical and graphical.

Abstract: Technologists often notice deformations after machining waffle construction of the shell. In that case, size characteristics go beyond tolerance field. Waffle constructions are widely used in aviation and rocket science, because thin-walled constructions allow decreasing mass of products. Results of calculations of standard machining parameters are given in the article. Review of literature sources allow to summarize the main solutions of the problems with deformations. Author has made a conclusion of technological restrictions and field of application of selected approaches.

Abstract: This work indicates that the prediction of the geometric indicators of the quality of the machined surface in the design of technological operations for milling a profile surface of work-pieces with low rigidity is possible, on the basis of an analysis of the elastic displacements of the technological system elements, the flexural rigidity of the work-piece as a function of its initial dimensions, the locating chart and the physical and mechanical characteristics of the material being processed. The article describes the characteristics of the elements of the technological system for the profile milling of work-pieces of low rigidity; The analytical dependencies linking the elastic displacements of the work-piece during the processing of various wood species with elements of the milling mode and the design parameters of the mill are given. Extreme total elastic displacements of the technological system during the cutting process are determined. Mathematical models of the maximum geometric error of the machined surface, as a function of the work-piece's flexural rigidity and the spindle unit, are established. Based on the results of the analysis, recommendations for improving the accuracy of the product were developed.

Abstract: Ural enrichment plants processing copper-porphyry deposits are produced chalcopyrite concentrates of the following chemical composition, %: 21.5 Cu, 0.1 Zn, 26.59 S, 24.52 Fe, 0.05 Pb, 0.04 Ni, 16.28 SiO₂ [1]. According to previous studies [2, 3, 21], such concentrates can be effectively treated using pressure oxidative leaching (POX). At temperature of 190–200 °C, partial oxygen pressure 4–6 bar and [H₂SO₄] = 15–30 g / L during 100-120 min about 98 % Cu was extracted. In this paper, an inluence of chalcopyrite concentrate preliminary grinding on efficiency of the POX stage was studied. It was found that even the finest grinding of the particle size class P₈₀ = 13 μm does not lead to significant intensification of process kinetics.

Abstract: In this paper, preheating temperature was investigated for the laser assisted machining (LAM) of Inconel 718 under different conditions for the milling test. The experimental results show that the requirement of laser power for the particularly preheating temperature proportionally increased with the table speed. The resultant cutting force for sufficient shearing work material in LAM was lower than conventional machining (CM) approximately 11, 21 and 28% for the cutting speed of 30, 50 and 75 m/min, respectively. The tool wear in LAM could be improved at relatively high cutting speed of 75 m/min and the hardness of machined surface in LAM was slightly higher than CM.