Investigation of micro-textured cutting tools used for face turning of alloy 718 with high-pressure cooling

There is an increasing demand to improve the service life of cutting tools during machining of heat resistant superalloys (HRSA). Various studies showed that textured cutting tools improved the tribological properties and reduced cutting forces, temperature, and tool wear. Surface texturing can be seen as a futuristic design to improve the performance of the cutting tool and to increase productivity. However, only limited research has been conducted in machining superalloys with textured inserts and high-pressure coolant. In this work, three different micro texture designs on both rake and flank face are investigated in combination with high-pressure coolant in machining Alloy 718. Due to better tool life predictability, carbide cutting tools are used in machining components made from superalloys. However, the disadvantage is that machining can only be done at lower cutting speed/feed rate/depth of cut with high tool wear rates. The experimental investigation using different tool wear analysis methods showed that the combination of a cylindrical dimple on the rake and the square pyramid texture on the flank surface improved the wear resistance of the tool. An increase in tool life of about 30% was achieved as compared with a regular insert for the investigated cutting conditions. Different levels of adhering workpiece material were observed on the rake face of textured tools. Furthermore, the chip backside showed imprints from the tool textures. The tool textures on the rake face have influenced the tool-chip friction conditions during cutting

Effects of high-pressure cooling in the flank and rake faces of WC tool on the tool wear mechanism and process conditions in turning of alloy 718

The exceptional properties of Heat Resistant Super Alloys (HRSA) justify the search for advanced technologies that can improve the capability of machining these materials. One such advanced technology is the application of a coolant at high pressure while machining. The aim is to achieve extended tool life, better chip control and improved surface finish. Another aim is to control the temperature in the workpiece/tool interface targeting for optimum cutting conditions. In most of the existing applications with high-pressure coolant media, the nozzles are positioned on the rake face side of the insert and they are directed towards the cutting edge (the high-temperature area). The coolant is applied at high-pressure to improve the penetration of the cooling media along the cutting edge in the interface between the insert and workpiece material (chip) as well as to increase chip breakability. However, the corresponding infusion of coolant media in the interface between the flank face of the insert and the work material has been previously only scarcely addressed, as is the combined effect of coolant applications on rake and clearance sides of the insert. The present work addresses the influence of different pressure conditions in (flank: 0, 4 and 8 MPa; rake: 8 and 16 MPa) on maximum flank wear, flank wear area, tool wear mechanism, and overall process performance. Round uncoated inserts are used in a set of face turning experiments, conducted on the widely used HRSA “Alloy 718” and run in two condition tests with respect to cutting speed (45 and 90 m/min). The results show that an increase in rake pressure from 8 to 16 MPa has certainly a positive impact on tool life. Furthermore, at higher vc of 90 m/min, cutting edge deterioration: due to an extensive abrasion and crack in the wear zone were the dominant wear mechanism. Nevertheless, the increase in coolant pressure condition to 16 MPa reduced the amount of abrasion on the tool compared to 8 MPa

Characterization of tool wear when machining Alloy 718 with high pressure cooling using conventional and surface-modified WC–Co tools

Coolant supplied by high pressure into the cutting zone has shown the lower thermal loads on the tool when machining difficult-to-cut materials as the Alloy 718. In this study, we investigate how the combination of high-pressure cooling and tool-surface modifications can lead to further improvements regarding tool life. The general approach is to enhance the coolant-tool interaction by increasing the contact area. Therefore, we machined cooling features into flank and rake faces of commercially available cemented tungsten carbide inserts. In this way, the surface area was increased by ~ 12 %. After the cutting tests, the tools were analyzed by scanning electron microscopy combined with energy-dispersive X-ray spectroscopy. Compared with conventional tools, the tool modifications reduced the flank wear by 45 % for the investigated cutting parameters. Furthermore, we were able to significantly increase the cutting speed and feed rate without failure of the tool. The investigated surface modifications have great potential to enhance the productivity of metal cutting processes.We like to thank the Region Västragötaland for funding in association with the PROSAM project. Sandvik Coromant is acknowledged for the support in manufacturing of inserts. Special thanks go to Andreas Gustafsson at the University West for helping with the insert design and Andreas Lindberg at GKN Aerospace Engine Systems AB for helping with experiments. Furthermore, Peter Sotkovszki at Chalmers is acknowledged for assistance in etching of the tool

A Study of Vacancies in Pure Aluminium and Their Role in the Diffusion of Lithium in a Dilute Al-Li Alloy Using the Embedded Atom Model

AbstractConstant temperature and pressure molecular dynamics are employed to study bulk Al and the substitutional Al-Li alloy using the embedded atom model. The appropriate embedding energy functionals and pair potentials have been determined using known experimental data of bulk Al and Li, together with the results of density functional theory studies of small Aln-Lim clusters and the ordered Al3Li crystallographic phase. The primary goal is to study the role vacancies play in the early stages of the nucleation and growth of the Al3Li crystallographic phase. To this end we present the preliminary results of a study of vacancy diffusion in Al, and Li diffusion through the Al matrix via a vacancy mechanism. In the present work the results of vacancy diffusion are analysed using a modified inverse Laplace transform, producing a continuous distribution of vacancy hopping times which reproduces the characteristic times for both the single and double vacancy hopping events.</jats:p

Endocrine correlates of placental permeability during gestation in the pig

Hormone and electrolyte concentrations were determined in amniotic and allantoic fluid collected from sows at 47-112 days of gestation and correlated with placental and fetal membrane electrolyte permeability. Significant differences between the electrolyte and endocrine gestational profiles of amniotic and allantoic fluid were identified. The principal endocrine correlate (r > 0.62; P < 0.01) of gestational changes in the sodium and chloride permeabilities of the porcine placenta and fetal membranes was found to be the concentration of oestrogen in the amniotic fluid

Characterization of tool wear when machining Alloy 718 with high pressure cooling using conventional and surface-modified WC–Co tools

Coolant supplied by high pressure into the cutting zone has shown the lower thermal loads on the tool when machining difficult-to-cut materials as the Alloy 718. In this study, we investigate how the combination of high-pressure cooling and tool-surface modifications can lead to further improvements regarding tool life. The general approach is to enhance the coolant-tool interaction by increasing the contact area. Therefore, we machined cooling features into flank and rake faces of commercially available cemented tungsten carbide inserts. In this way, the surface area was increased by ~ 12 %. After the cutting tests, the tools were analyzed by scanning electron microscopy combined with energy-dispersive X-ray spectroscopy. Compared with conventional tools, the tool modifications reduced the flank wear by 45 % for the investigated cutting parameters. Furthermore, we were able to significantly increase the cutting speed and feed rate without failure of the tool. The investigated surface modifications have great potential to enhance the productivity of metal cutting processes.We like to thank the Region Västragötaland for funding in association with the PROSAM project. Sandvik Coromant is acknowledged for the support in manufacturing of inserts. Special thanks go to Andreas Gustafsson at the University West for helping with the insert design and Andreas Lindberg at GKN Aerospace Engine Systems AB for helping with experiments. Furthermore, Peter Sotkovszki at Chalmers is acknowledged for assistance in etching of the tool