The Influence of Cryogenic Coolants in Machining of Ti–6Al–4V

Author(s):  
B. Dilip Jerold ◽  
M. Pradeep Kumar

Machining of titanium alloy Ti–6Al–4V is a challenging task because of the greatly increased cutting temperature that results in short tool life. Numerous attempts have been made in the past by employing various cutting fluids for machining purpose, including liquid nitrogen (LN2) as the cryogenic coolant. This study deals with the influence of cryogenic coolants, especially LN2 and carbon dioxide (CO2), in machining of Ti–6Al–4V and its effects on cutting temperature, cutting forces, surface roughness, chip morphology, and tool wear. The results obtained in cryogenic machining are compared with that of dry and wet machining. Cutting temperature was reduced to an extent of 36% and 47% in cryogenic CO2 machining and cryogenic LN2 machining in comparison with wet machining. The application of CO2 produced reduced cutting forces up to 24% and improved surface finish up to 48% compared to cryogenic LN2 machining. It also produced better chip control and minimized tool wear than dry, wet, and LN2 machining.

Author(s):  
Vivek Bajpai ◽  
Ineon Lee ◽  
Hyung Wook Park

Titanium alloys are well-known material because of the excellent mechanical/chemical properties, corrosion resistance and light weight. These alloys are widely used in the high performance applications such as; aerospace, aviation, bio-implants, turbine blades etc. Machining is commonly used to create products out of Ti alloys. Despite of good material properties, Ti alloys have low thermal conductivity, poor machinability, burr formation, high machining temperature, tool wear and poor machinability. The tool wear and high machining temperature can be controlled through coolant. Cryogenic fluid (liquid nitrogen) is a common material used as coolant in various machining process. The current work is focused on the modeling of cryogenic machining on titanium alloy (Ti6Al4V). Dry machining and cryogenic machining processes are modeled for the chip formation and cutting forces in 2D. Experimental works have been performed to validate the model based on the cutting forces and chip morphology. It is showed that the model is capturing the process, evident by the cutting forces and the chip morphology. The error in prediction is limited to 18%. Model showed that the cutting forces are increasing in cryogenic machining due to the increased strength of the workpiece at low temperature. Chip formation is well captured by the current model. Shear band width have been captured in dry machining. Chip curling has been captured at dry and cryogenic machining. It is expected that the model can further useful in the selection of cryogenic process parameter, such as, flow rate, application techniques etc.


Author(s):  
P. V. Krishna ◽  
R. R. Srikant ◽  
N. Parimala

This work is motivated by environmentally conscious machining and focus on the basic properties and applicability of nano cutting fluids in machining. Cutting fluids are formulated by dispersing carbon nanotubes (CNT) in coconut oil (CC) with varying percentage of nanoparticle inclusions (NPI). The properties such as density, heat transfer coefficient, dynamic viscosity and thermal conductivity are determined before their application. The formulated nanofluids are applied during machining through minimum quantity lubrication (MQL) technique. Microbial contamination and biodegradability tests are conducted to assess the quality of nanocutting fluids. Viscosity is found to decrease with increase in temperature where, as specific heat slightly decreased with an increase in NPI for CNT dispersed fluids. It is observed that nanofluids in MQL upshot in the reduction of cutting force, cutting temperature, tool wear and surface roughness. CNT dispersed cutting fluids at 0.5% NPI and speed of 60 m/min, 0.131 mm/rev feed and 0.5 mm depth of cut (DOC) shown better performance in the selected range of parameters. Machining performance is more influenced by the percentage of nanoparticles and then the depth of cut, speed and feed respectively. For the cutting conditions, the influence of DOC in obtaining minimum cutting forces and reducing cutting temperatures is found to be 85% and 45% respectively for nBA dispersed fluids. The extent of influence of %NPI is found to be 35.19% for CNT dispersed fluids to obtain reduced cutting forces, cutting temperatures, tool wear and surface roughness according to GRA analysis. Microbial contamination is observed to be the least for 0.5% NPI dispersed fluids. It is also identified that nano cutting fluids used in this work are biodegradable and biologically treatable for disposal as well.


Author(s):  
Xiangqin Zhang ◽  
Xueping Zhang ◽  
A. K. Srivastava

To predict the cutting forces and cutting temperatures accurately in high speed dry cutting Ti-6Al-4V alloy, a Finite Element (FE) model is established based on ABAQUS. The tool-chip-work friction coefficients are calculated analytically using the measured cutting forces and chip morphology parameter obtained by conducting the orthogonal (2-D) machining tests. It reveals that the friction coefficients between tool-work are 3∼7 times larger than that between tool-chip, and the friction coefficients of tool-chip-work vary with feed rates. The analysis provides a better reference for the tool-work-chip friction coefficients than that given by literature empirically regardless of machining conditions. The FE model is capable of effectively simulating the high speed dry cutting process of Ti-6Al-4V alloy based on the modified Johnson-Cook model and tool-work-chip friction coefficients obtained analytically. The FE model is further validated in terms of predicted forces and the chip morphology. The predicted cutting force, thrust force and resultant force by the FE model agree well with the experimentally measured forces. The errors in terms of the predicted average value of chip pitch and the distance between chip valley and chip peak are smaller. The FE model further predicts the cutting temperature and residual stresses during high speed dry cutting of Ti-6Al-4V alloy. The maximum tool temperatures exist along the round tool edge, and the residual stress profiles along the machined surface are hook-shaped regardless of machining conditions.


2010 ◽  
Vol 443 ◽  
pp. 382-387 ◽  
Author(s):  
Somkiat Tangjitsitcharoen ◽  
Suthas Ratanakuakangwan

This paper presents the additional work of the previous research in order to verify the previously obtained cutting condition by using the different cutting tool geometries. The effects of the cutting conditions with the dry cutting are monitored to obtain the proper cutting condition for the plain carbon steel with the coated carbide tool based on the consideration of the surface roughness and the tool life. The dynamometer is employed and installed on the turret of CNC turning machine to measure the in-process cutting forces. The in-process cutting forces are used to analyze the cutting temperature, the tool wear and the surface roughness. The experimentally obtained results show that the surface roughness and the tool wear can be well explained by the in-process cutting forces. Referring to the criteria, the experimentally obtained proper cutting condition is the same with the previous research except the rake angle and the tool nose radius.


2013 ◽  
Vol 690-693 ◽  
pp. 2030-2035
Author(s):  
Shu Bao Yang ◽  
Hong Chao Ni ◽  
Guo Hui Zhu

Ti6Al4V alloy is widely used in the aircraft industry, marine and the commercial applications due to its excellent comprehensive properties. However, its poor machinability prevents it from application widely, and the rapid tool wear is one of the key factors. The FEM models of cutting titanium alloy are established. The effect of tool wear on chip morphology, cutting temperature and cutting force are studied. The simulation results show that: the cutting force and cutting temperature will rise with the increase of tool wear. Furthermore, the degree of chip deformation will improve, but the frequency of serrated chip tooth occurred will decrease.


Author(s):  
Yusuf Kaynak ◽  
Armin Gharibi

Titanium alloy Ti-5Al-5V-3Cr-0.5Fe (Ti-5553) is a new generation of near-beta titanium alloy that is commonly used in the aerospace industry. Machining is one of the manufacturing methods to produce parts that are made of this near-beta alloy. This study presents the machining performance of new generation near-beta alloys, namely, Ti-5553, by focusing on a high-speed cutting process under cryogenic cooling conditions and dry machining. The machining experiments were conducted under a wide range of cutting speeds, including high speeds that used liquid nitrogen (LN2) and carbon dioxide (CO2) as cryogenic coolants. The experimental data on the cutting temperature, tool wear, force components, chip breakability, dimensional accuracy, and surface integrity characteristics are presented and were analyzed to evaluate the machining process of this alloy and resulting surface characteristics. This study shows that cryogenic machining improved the machining performance of the Ti-5553 alloy by substantially reducing the tool wear, cutting temperature, and dimensional deviation of the machined parts. The cryogenic machining also produced shorter chips as compared to dry machining.


Coatings ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1515
Author(s):  
Jinxing Wu ◽  
Lin He ◽  
Yanying Wu ◽  
Chaobiao Zhou ◽  
Zhongfei Zou ◽  
...  

Tool-chip friction increases cutting temperature, aggravates tool wear, and shortens the service life of cutting tools. A micro-groove design of the rake face can improve the wear performance of the tool. In this study, we used the finite element simulation “Deform” to obtain the temperature field distribution of the tool rake face. The size of the micro-groove was determined by selecting a suitable temperature field combined with the characteristics of tool–chip flow in the cutting process, and the tool was prepared using powder metallurgy. The three-direction cutting forces and tool tip temperature were obtained by a cutting test. Compared with the original turning tool, the cutting force and cutting temperature of the micro-groove tool were reduced by more than 20%, the friction coefficient was reduced by more than 14%, the sliding energy was reduced and the shear energy was greatly decreased. According to the analysis of tool wear by SEM (scanning electron microscope) and EDS (energy dispersive X-ray spectroscopy), the crater wear, adhesive wear and oxidation wear of the micro-groove tool were lower than those of the original turning tool. In particular, the change in the crater wear area on the rake face of the original tool and the micro-groove tool was consistent with the cutting temperature and the wear width of the flank face. On the whole, the crater wear area and the change rate of the crater wear area of the micro-groove tool were smaller. Due to the proper microgroove structure of the rake face, the tool-chip contact area decreased, and the second rake angle of the tool became larger. Hence, the tool-chip friction, cutting forces, cutting energy consumption were reduced, tool wear was improved, and the service life of the micro-groove tool was five times longer than that of the original tool.


Author(s):  
Douglas J. MacLean ◽  
Kim F. Hayes ◽  
Thomas Barnard ◽  
Timothy Hull ◽  
Ye Eun Park ◽  
...  

This paper investigates the influence of supercritical carbon dioxide (scCO2) metalworking fluids on tool wear in two automotive manufacturing processes. scCO2 is a low-cost minimum quantity lubrication (MQL) system with excellent cooling characteristics. In valve seat machining of sintered steel with cubic boron nitride (CBN) inserts, scCO2 reduced tool wear by up to 25% and cutting forces by 10% when compared with the benchmark water-based flood metalworking fluid currently used in production operations. In end milling of compacted graphite iron (CGI) with uncoated carbide inserts, scCO2 reduced tool wear by up to 50% when compared with the currently used metalworking fluid. These results are consistent with those from other applications that show scCO2-based metalworking fluids have the potential to reduce tool wear and cutting forces when compared with commonly used water-based metalworking fluids. At the same time scCO2 is environmentally benign, eliminates metalworking fluid maintenance and disposal, and removes the major health risks associated with today’s metalworking fluids.


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