Investigation of the Cutting Fluid Incidence Angle Direction in Turning Grade 5 ELI Titanium Alloy under High-Pressure Cooling Conditions.

The use of high-pressure cooling (HPC) in machining can increase the efficiency and improve process stability through more effective breaking and chip evacuation. Turning tests of the Grade 5 ELI titanium alloy were carried out using cemented carbide tools and taking into account the direction of feeding of the cutting liquid. Measurements of the components of the total cutting force were carried out for feeds in the range f = <0.08; 0.13> mm/rev and two angular settings (i.e., angle α = <30°; 90°> and ß = <0°; 60°>) of the nozzle. The chip breakage coefficient was determined. It was shown that the cutting force values depended on the feed value, and the angle of feeding of the cutting fluid did not significantly affect the values of the cutting forces. Despite the different forms of chips obtained, the applied method of searching for the best conditions was unsuccessful and no significant effect on the values of the chip breaking coefficient Cch was observed. To determine the best nozzle setting, it is useful to determine the working area of the chip breaker. Due to the shape of the chip, the optimal angular setting for the nozzle that supplied the cutting fluid was α = 60° and ß = 30°. In addition, it was observed that the angle of incidence of the cutting fluid jet could affect the chip formation process and support the chip cracking process.

Surface Topographic Features after Milling of Additively Manufactured AlSi10Mg Aluminum Alloy.

The article presents selected issues related to material quality manufactured by selective laser sintering of AlSi10Mg alloy powder after milling. The workpiece was prepared and machined by down-milling and up-milling with tools made of high-speed steel. Breaches, pores and failure-like cracks on the machined surface were found, which negatively influenced the values of 3D surface roughness parameters. The occurring phenomena were analyzed and proposals for their explanation were made. The results of this research describe the effect of cutting parameters (the feed rate of f = 0.013-0.05 mm/tooth) on the values of parameters describing the surface quality and benchmarks. Topography measurements and 3D surface roughness parameters are presented, as well as the results of microscopic surface analysis. It was found that for aluminum alloy produced by the direct metal laser sintering (DMLS) method, the recommended machining method is down-milling.

Method of Data Selection for Turning of Inconel 718 Alloy Obtained by Casting and Laser Sintering Powder.

This article focuses on the issues related to the machining of DMLS (Direct Metal Laser Sintering) laser sintered parts made of Inconel 718 alloy. Longitudinal turning with CBN (cubic boron nitride) tool inserts is analyzed. The authors made an attempt to establish a procedure to find the optimal finishing cutting parameters while minimizing the specific cutting force and taking into account the machined surface quality criterion. During experiments the influence of cutting data on the values of cutting force and specific cutting force were performed. Moreover, the results of measurements of surface roughness parameters and the results of analysis of chip form are presented as well. Cast Inconel 718 has also been tested for comparative purposes. The variability of the material's hardening state during machining was found, as well as the variability of the specific cutting force value as a function of the cross-sectional shape of the cutting layer. The values of all components of the total cutting force for turning the material obtained by the additive method are lower than for turning the cast material by approximately 32%. At the end of the article, the authors present an application of the proposed optimization algorithm. It was established that by changing the cross-section shape of the cutting layer, it was possible to perform the turning process at a specific cutting force value of 22% less, which is achieved by reducing the cross-section size.

Cutting Forces and Tool Wear Investigation during Turning of Sintered Nickel-Cobalt Alloy with CBN Tools.

This article describes issues related to the machining of parts made of sintered nickel-cobalt alloy. Longitudinal turning with a CBN (cubic boron nitride) tool was analyzed. The results of experiments showed the influence of cutting parameters in the field of finishing machining on the values of cutting forces and specific cutting force, taking into account the wear of the cutting edge. Measurements and analysis of the topography and roughness parameters of the machined surface, as well as the cutting tool wear, were presented. The microscopic examination showed that the average grain size of the sintered nickel-cobalt alloy was 3.22 ± 0.1 (µm). The presence of the hardening state variability of the material during machining, as well as the value of the cutting force fluctuation as a function of the tool wear VB, were stated. The specific cutting force values increased to a small degree for the tool wear in the range of VB = 0-0.2 mm, and reached similar values in the range kc = 5500-7500 N/mm2. The specific cutting force values increased significantly for wear VB > 0.2 mm and were characterized by a large variability. The occurring phenomena were analyzed and several explanations were proposed. A recommendation was developed for the machining of parts made of sintered nickel-cobalt alloy. The Taguchi method was used in the experiment methodology.

Reduction of Power Consumption by Chip Breakability Control in Ti6Al4V Titanium Alloy Turning.

The paper concerns the problem of energy savings in turning of titanium alloy Ti6Al4V. Since this alloy belongs to difficult to cut materials, there is a problem with chip forming and breaking. The turning process is often supported by implementing a high-pressure cooling (HPC) system. Based on the observations and the adopted chip classification method, the authors proved that it is not necessary to use this method in roughing operations, however it helps with the chips breaking process in finishing operations. A general algorithm for machining optimization due to the chip geometry is presented and described. In the presented case, it was shown that the acceptable chip geometry could be obtained with a reduced power consumption by approximately Pc = 0.5 kW. The authors concluded that it was not necessary to apply cutting data and a coolant system to achieve perfect chip geometry. An acceptable form was often sufficient, while requiring less energy. An additional factor resulting from the operation of systems supporting the cutting process, such as an HPC device, should be taken into account in the formula concerning the energy consumption (EC) of a computerized numerical control (CNC) machine tool.

Evaluation of Surface Roughness and Defect Formation after The Machining of Sintered Aluminum Alloy AlSi10Mg.

This article presents selected issues related to the workpiece surface quality after machining by the laser sintering of AlSi10MG alloy powder. The surfaces of the workpiece were prepared and machined by longitudinal turning with tools made of sintered carbides. The occurrence of breaches on the machined material surface was found, which negatively influence the values of 3D surface roughness parameters. The occurring phenomena were analyzed and proposals for their explanation were made. Guidelines for the machining of workpieces achieved by the laser sintering of powders were developed. The lowest value of the 3D roughness parameters was obtained for f = 0.06 mm/rev, ap = 0.5-1.0 mm, and for the nose radius of cutting insert rε = 0.8 mm. The results of research on the effect of cutting parameters on the values of parameters describing the surface quality are presented. Topography measurements and 3D surface roughness parameters are presented, as well as the results of a microscopic 3D surface analysis. Taguchi's method was used in the research methodology.

Turning Titanium Alloy, Grade 5 ELI, With the Implementation of High Pressure Coolant.

In the machining of difficult-to-cut alloys, such as titanium-based alloys, the delivery of a cutting fluid with high pressure can increase machining efficiency and improve process stability through more efficient chip breaking and removing. Proper selection of machining conditions can increase the productivity of the process while minimizing production costs. To present the influence of cutting fluid pressure and chip breaker geometry on the chip breaking process for various chip cross-sections Grade 5 ELI titanium alloy turning tests were carried out using carbide tools, H13A grade, with a -SF chip breaker geometry under the cutting fluid pressure of 70 bar. Measurements of the total cutting force components for different cutting speeds, feeds, and cutting depth in finishing turning were carried out. The analysis of the obtained chips forms and the application area of the chip breaker have been presented. It was proved that for small depth of cut (leading to small chip cross-section) the cutting fluid pressure is the main cause of the chip breakage, since the insert chip breaker does not work. On the other hand, for bigger depths of cut where the chip breaker goes in action, the cutting fluid pressure only supports this process. For medium values of depths of cut the strength of chip is high enough so that the pressure of the cutting fluid cannot cause chip breaking. A chip groove is not filled completely so the chip breaker cannot play its role.

Turning Research of Additive Laser Molten Stainless Steel 316L Obtained by 3D Printing.

This paper presents the characteristic of 316L steel turning obtained by 3D printing. The analysis of the influence of turning data on the components of the total cutting force, surface roughness and the maximum temperature values in the cutting zone are presented. The form of chips obtained in the machining process was also analyzed. Statistical analysis of the test results was developed using the Taguchi method.