Please wait a minute...

Frontiers of Mechanical Engineering

Front. Mech. Eng.    2020, Vol. 15 Issue (3) : 504-515     https://doi.org/10.1007/s11465-020-0586-2
RESEARCH ARTICLE
Machinability of damage-tolerant titanium alloy in orthogonal turn-milling
Tao SUN1(), Lufang QIN1, Junming HOU2, Yucan FU3
1. Jiangsu Key Laboratory of Large Engineering Equipment Detection and Control, Xuzhou University of Technology, Xuzhou 221111, China
2. Industrial Center, Nanjing Institute of Technology, Nanjing 211167, China
3. College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
Download: PDF(3327 KB)   HTML
Export: BibTeX | EndNote | Reference Manager | ProCite | RefWorks
Abstract

The damage-tolerant titanium alloy TC21 is used extensively in important parts of advanced aircraft because of its high strength and durability. However, cutting TC21 entails problems, such as high cutting temperature, high tool tip stress, rapid tool wear, and difficulty guaranteeing processing quality. Orthogonal turn-milling can be used to solve these problems. In this study, the machinability of TC21 in orthogonal turn-milling is investigated experimentally to optimize the cutting parameters of orthogonal turn-milling and improve the machining efficiency, tool life, and machining quality of TC21. The mechanism of the effect of turn-milling parameters on tool life is discussed, the relationship between each parameter and tool life is analyzed, and the failure process of a TiAlN-coated tool in turn-milling is explored. Experiments are conducted on the integrity of the machined surface (surface roughness, metallographic structure, and work hardening) by turn-milling, and how the parameters influence such integrity is analyzed. Then, reasonable cutting parameters for TC21 in orthogonal turn-milling are recommended. This study provides strong guidance for exploring the machinability of difficult-to-cut-materials in orthogonal turn-milling and improves the applicability of orthogonal turn-milling for such materials.

Keywords orthogonal turn-milling      damage-tolerant titanium alloy      tool life and failure      machined surface integrity      machinability     
Corresponding Author(s): Tao SUN   
Just Accepted Date: 16 April 2020   Online First Date: 14 May 2020    Issue Date: 03 September 2020
 Cite this article:   
Tao SUN,Lufang QIN,Junming HOU, et al. Machinability of damage-tolerant titanium alloy in orthogonal turn-milling[J]. Front. Mech. Eng., 2020, 15(3): 504-515.
 URL:  
http://journal.hep.com.cn/fme/EN/10.1007/s11465-020-0586-2
http://journal.hep.com.cn/fme/EN/Y2020/V15/I3/504
Fig.1  Microstructure of raw TC21.
Composition Weight percent/wt.%
Al 6.78
Mo 2.87
Sn 2.32
Nb 2.31
Zr 2.19
Cr 0.77
Si 0.09
Ti Balance
Tab.1  Chemical compositions of TC21 [6]
Fig.2  Photograph of cutting via turn-milling.
Fig.3  Dimensions of the insert and tool holder for turn-milling. (a) R390-11 T3 08E-PLW 1130 insert and (b) R390-020A22-11M tool holder. Unit: mm.
Fig.4  Three movements in orthogonal turn-milling.
Fig.5  Eccentricity of orthogonal turn-milling.
Tool speed nt/(r?min?1) Workpiece speed nw/(r?min?1) Cutting depth ap/mm Feed rate per revolution fa/(mm?r?1) Eccentricity e/mm
1500, 2000, 2500 2, 5, 8 0.5, 1, 1.5 2, 4, 6 –8, 0, 8
Tab.2  Cutting parameters in the orthogonal turn-milling experiments
Fig.6  Effects of parameters on tool life in orthogonal turn-milling: (a) Down milling and up milling, (b) eccentricity e, (c) tool speed nt, (d) workpiece speed nw, (e) feed rate per revolution fa, and (f) cutting depth ap.
Fig.7  Tool life and material removal rate of turning and orthogonal turn-milling for TC21.
Fig.8  Failure process of the insert in orthogonal turn-milling (nt = 2000 r/min, nw = 5 r/min, fa = 4 mm/r, e = -8 mm, ap = 0.5 mm). (a) Cutting time= 17 min, flank-face wear of insert= 0.1 mm (20×); (b) cutting time= 24 min, flank-face wear of insert= 0.17 mm (20×); (c) cutting time= 32 min, flank-face wear of insert= 0.28 mm (20×).
Fig.9  Formation of the cutting layer in orthogonal turn-milling.
Fig.10  Scanning electron microscope (SEM) images of the round corner of the flank face in the failure stage of the insert. (a) Failed tool; SEM image magnified (b) 100× and (c) 300×.
Fig.11  Scanning electron microscope (SEM) image of the round corner of the rake face in the failure stage of the insert. (a) Failed tool and (b) SEM image magnified 500×.
Fig.12  Energy-dispersive X-ray spectroscopy of points 1 and 2 in Fig. 11. (a) Point 1 and (b) point 2.
Point Chemical composition/wt.%
Ti O Sn W C Co N Al
Point 1 93.28 2.45 1.67 1.43 1.04 0.13 0.00 0.00
Point 2 1.02 7.89 0.00 71.44 16.41 2.08 0.77 0.40
Tab.3  Chemical compositions of points 1 and 2
Fig.13  Effects of (a) eccentricity e, (b) workpiece speed nw, and (c) feed rate per revolution fa on Ra in orthogonal turn-milling.
Fig.14  Metallographic structure of the machined surface layer in orthogonal turn-milling. (a) ap = 0.5 mm, nt = 2000 r/min, nw = 8 r/min, e = -8 mm, fa = 4 mm/r, Z = 1, and T = 27 min; (b) ap = 0.5 mm, nt = 2500 r/min, nw = 5 r/min, e = -8 mm, fa = 4 mm/r, Z = 1, and T = 33 min; (c) ap = 0.5 mm, nt = 2000 r/min, nw = 2 r/min, e = -8 mm, fa = 4 mm/r, Z = 1, and T = 88 min; (d) ap= 0.5 mm, nt = 2000 r/min, nw = 5 r/min, e = -8 mm, fa = 2 mm/r, Z = 1, and T = 64 min.
Fig.15  Microhardness of the machined surface layer in orthogonal turn-milling.
1 T Sun, Y C Fu, L He, et al. Machinability of plunge milling for damage-tolerant titanium alloy TC21. International Journal of Advanced Manufacturing Technology, 2016, 85(5–8): 1315– 1323
https://doi.org/10.1007/s00170-015-8022-1
2 P Wang, M L S Nai, W J Sin, et al. Effect of overlap distance on the microstructure and mechanical properties of in situ welded parts built by electron beam melting process. Journal of Alloys and Compounds, 2019, 772: 247–255
https://doi.org/10.1016/j.jallcom.2018.09.093
3 P Wang, M Todai, T Nakano. Beta titanium single crystal with bone-like elastic modulus and large crystallographic elastic anisotropy. Journal of Alloys and Compounds, 2019, 782: 667–671
https://doi.org/10.1016/j.jallcom.2018.12.236
4 Q Shi, L Li, N He, et al. Experimental study in high speed milling of titanium alloy TC21. International Journal of Advanced Manufacturing Technology, 2013, 64(1–4): 49–54
https://doi.org/10.1007/s00170-012-3997-3
5 Q Shi, N He, L Li, et al. Analysis on surface integrity during high speed milling for new damage-tolerant titanium alloy. Transactions of Nanjing University of Aeronautics & Astronautics, 2012, 29(3): 222–226
6 T Sun, Y C Fu, L He, et al. Cutting machinability for damage-tolerant titanium alloy. Journal of Shanghai Jiaotong University, 2016, 50(7): 1017–1022 (in Chinese)
7 H X Zhang, J Zhao, F Z Wang, et al. Cutting forces and tool failure in high-speed milling of titanium alloy TC21 with coated carbide tools. Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture, 2015, 229(1): 20–27
https://doi.org/10.1177/0954405414526578
8 P Wang, L Wu, Y Feng, et al. Microstructure and mechanical properties of a newly developed low Young’s modulus Ti–15Zr–5Cr–2Al biomedical alloy. Materials Science and Engineering: C, 2017, 72: 536–542
https://doi.org/10.1016/j.msec.2016.11.101
9 H Schulz, G Spur. High speed turn-milling—A new precision manufacturing technology for the machining of rotationally symmetrical workpieces. CIRP Annals, 1990, 39(1): 107–109
https://doi.org/10.1016/S0007-8506(07)61013-0
10 H Schulz, T Kneisel. Turn-milling of hardened steel—An alternative to turning. CIRP Annals, 1994, 43(1): 93–96
https://doi.org/10.1016/S0007-8506(07)62172-6
11 S K Choudhury, K S Mangrulkar. Investigation of orthogonal turn-milling for the machining of rotationally symmetrical work pieces. Journal of Materials Processing Technology, 2000, 99(1–3): 120–128
https://doi.org/10.1016/S0924-0136(99)00397-0
12 S K Choudhury, J B Bajpai. Investigation in orthogonal turn-milling towards better surface finish. Journal of Materials Processing Technology, 2005, 170(3): 487–493
https://doi.org/10.1016/j.jmatprotec.2004.12.010
13 S Ekinović, E Begović, A Silajdžija. Comparison of machined surface quality obtained by high-speed machining and conventional turning. Machining Science and Technology, 2007, 11(4): 531–551
https://doi.org/10.1080/10910340701804112
14 M Pogacnik, J Kopac. Dynamic stabilization of the turn-milling process by parameter optimization. Proceedings of the Institution of Mechanical Engineers. Part B: Journal of Engineering Manufacture, 2000, 214(2): 127–135
https://doi.org/10.1243/0954405001517504
15 L D Zhu, H N Li, W S Wang. Research on rotary surface topography by orthogonal turn-milling. International Journal of Advanced Manufacturing Technology, 2013, 69(9–12): 2279–2292
https://doi.org/10.1007/s00170-013-5202-8
16 C Ratnam, K Arun Vikram, B S Ben, et al. Process monitoring and effects of process parameters on responses in turn-milling operations based on SN ratio and ANOVA. Measurement, 2016, 94: 221–232
https://doi.org/10.1016/j.measurement.2016.07.090
17 U Karagüzel, M Bakkal, E Budak. Process modeling of turn-milling using analytical approach. Procedia CIRP, 2012, 4: 131–139
https://doi.org/10.1016/j.procir.2012.10.024
18 E Uysal, U Karagüzel, E Budak, et al. Investigating eccentricity effects in turn-milling operations. Procedia CIRP, 2014, 14: 176–181
https://doi.org/10.1016/j.procir.2014.03.042
19 U Karagüzel, E Uysal, E Budak, et al. Analytical modeling of turn-milling process geometry, kinematics and mechanics. International Journal of Machine Tools and Manufacture, 2015, 91: 24–33
https://doi.org/10.1016/j.ijmachtools.2014.11.014
20 U Karaguzel, M Bakkal, E Budak. Mechanical and thermal modeling of orthogonal turn-milling operation. Procedia CIRP, 2017, 58: 287–292
https://doi.org/10.1016/j.procir.2017.03.191
21 Z K Niu, L Jiao, S Q Chen, et al. Surface quality evaluation in orthogonal turn-milling based on box-counting method for image fractal dimension estimation. Nanomanufacturing and Metrology, 2018, 1(2): 125–130
https://doi.org/10.1007/s41871-018-0015-x
22 K R Berenji, M E Kara, E Budak. Investigating high productivity conditions for turn-milling in comparison. Procedia CIRP, 2018, 77: 259–262
https://doi.org/10.1016/j.procir.2018.09.010
23 C Benjamin, N Andreas, C Andreas, et al. Investigation of surface properties in turn milling of particle-reinforced aluminium matrix composites using MCD-tipped tools. International Journal of Advanced Manufacturing Technology, 2019, 8: 1–14
24 T Sun, L F Qin, Y C Fu, et al. Chatter stability of orthogonal turn-milling analyzed by complete discretization method. Precision Engineering, 2019, 56: 87–95
https://doi.org/10.1016/j.precisioneng.2018.10.012
25 Q An, J Chen, Z Tao, et al. Experimental investigation on tool wear characteristics of PVD and CVD coatings during face milling of Ti6242S and Ti-555 titanium alloys. International Journal of Refractory Metals & Hard Materials, 2020, 86: 105091
https://doi.org/10.1016/j.ijrmhm.2019.105091
Related articles from Frontiers Journals
[1] Fangyu PENG,Wei WANG,Rong YAN,Xianyin DUAN,Bin LI. Variable eccentric distance-based tool path generation for orthogonal turn-milling[J]. Front. Mech. Eng., 2015, 10(4): 352-366.
Viewed
Full text


Abstract

Cited

  Shared   0
  Discussed