1 Introduction
2 Nanoparticle-enhanced coolants
2.1 Base fluids
Tab.1 Machinability of common vegetable oils when grinding nickel-based alloys [48], reproduced with permission from Elsevier |
Base oil | Friction coefficient | Specific grinding energy/(J·mm‒3) | G-ratio |
---|---|---|---|
Pure soybean oil | 0.41 | 91.02 | 26.50 |
Pure peanut oil | 0.45 | 98.62 | 22.92 |
Pure maize oil | 0.34 | 80.90 | 29.15 |
Pure rapeseed oil | 0.39 | 80.94 | 29.13 |
Pure palm oil | 0.33 | 78.85 | 28.63 |
Pure castor oil | 0.30 | 73.47 | 26.89 |
Pure sunflower oil | 0.36 | 86.54 | 28.19 |
2.2 Nano-enhanced phases
Tab.2 Commonly used nano-enhanced phases for machining |
Categories | Nano-enhanced phases |
---|---|
Spherical nano-enhanced phases | Al2O3, SiO2, ZrO2, SiC, ND |
Threadiness nano-enhanced phases | CuO2, MnO2, TiO2, ZnO, CNTs |
Stratiform nano-enhanced phases | CBN, GNP, MoO3, HBN, MoS2 |
Notes: CBN, cubic boron nitride; ND, diamond. |
2.3 Preparation
2.4 Stability
2.4.1 Destabilizing factors
2.4.2 Stability strategies
Tab.3 Surfactants commonly used in machining |
Type | Surfactant |
---|---|
Nonionic | Alkylphenol ethoxylates, octyl phenol ethoxylate, polyvinylpyrrolidone |
Cationic | Sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium oleate |
Anionic | Gum arabica, dodecyl trimethyl ammonium bromide, cetyltrimethylammonium bromide, cetyltrimethylammonium chloride |
Hermaphroditic | Lecithin, hydroxy sulfobetaine |
3 Thermophysical properties
3.1 Thermal conductivity
3.1.1 Effect of temperature and concentration
Fig.9 Thermal conductivity as a function of temperature and concentration: (a) variation of graphene (GNP) nanoparticle-enhanced coolants (NPECs) thermal conductivity with temperature; (b) variation of thermal conductivity of Al2O3 and Al‒GNP NPEC with temperature [109]; (c) variation of GNP thermal conductivity with concentration in three different base oils [50]; (d) variation of thermal conductivity of GNP with concentration [110]. Reproduced with permissions from Refs. [50,109,110] from Elsevier. |
3.1.2 Influence of other factors
3.2 Viscosity
3.2.1 Effect of temperature and concentration
Fig.11 Viscosity as a function of temperature and concentration. (a) Variation of graphene nanoparticle-enhanced coolant (NPEC) viscosity with temperature [50]; (b) variation of viscosity with temperature for six NPECs [104]; (c) viscosity variation with concentration for three different NPECs [138]; (d) variation of MWCNT‒MgO hybrid NPECs viscosity with solid volume fraction [139]. CNTs: carbon nanotubes; HBN: hexagonal boron nitride; MWCNT: multi-walled carbon nanotube; ND: diamond. Reproduced with permissions from Refs. [50,104,138,139] from Elsevier. |
3.2.2 Influence of other factors
3.3 Wetting performance
Tab.4 NPEC contact angles on a Ni-based workpiece |
Nanoparticle-enhanced coolants | Contact angle/(° ) |
---|---|
SiO2 | 49.2 |
PCD | 43.5 |
CNT | 47.5 |
MoS2 | 46.0 |
Al2O3 | 45.5 |
ZrO2 | 41.5 |
Notes: PCD, polycrystalline diamond; CNT, carbon nanotube. |
3.4 Tribological properties
Fig.14 (a) Macroscopic lubrication mechanism model of stratiform nano-enhanced phases; (b) effect of different types on the coefficient of friction (COF) [129], reproduced with permission from Elsevier; (c) effect of nano-enhanced phase concentration on COF [109], reproduced with permission from Springer Nature. GNP: graphene; HBN: hexagonal boron nitride. |
4 Applications in machining
4.1 Turning
4.1.1 Cutting temperature
4.1.2 Tool wear
Fig.17 (a) Tool wear types based on ISO 3685 [202], reproduced with permission from Elsevier; (b) flank wear based on machining time [192], reproduced with permission from Springer Nature; (c) tip wear as an evaluation of different lubrication–cooling strategies [205], reproduced with permission from Elsevier; (d) tool life at different cutting speeds [115], reproduced with permission from Elsevier. MQL: minimum quantity lubrication; MQC: minimal quantitative cooling; PTFE: polytetrafluoroethylene. |
4.1.3 Surface quality
Fig.19 (a) Variation of surface roughness Ra with cutting speed [110], reproduced with permission from Elsevier; (b) variation of surface roughness for two different environments at different cutting speeds [192], reproduced with permission from Springer Nature; (c) machined surfaces under different working conditions [201], reproduced under the terms of the CC BY license. |
4.2 Milling
4.2.1 Milling temperature
4.2.2 Tool wear
Fig.22 Tool wear and life evolution patterns under different cooling–lubrication strategies [59]: (a) maximum width of the tool flank wear zone; (b) milling cutter wear curve; (c) cutting edge in the final stage. MQL: minimum quantity lubrication; GNP: graphene. Reproduced with permission from Springer Nature. |
4.2.3 Surface quality
4.3 Grinding
4.3.1 Grinding temperature
4.3.2 Specific grinding energy
Fig.27 (a) Effect of each lubrication method on specific grinding energy; (b) percentage reduction in specific grinding energy [231]; (c) specific grinding energy at six operating conditions [106]; (d) variation in specific grinding energy with different concentrations of graphene (GNP) in different vegetable oils [50]. MQL: minimum quantity lubrication; PMQL: pure MQL; GMQL: graphene MQL. Reproduced with permissions from Refs. [50,106,231] from Elsevier. |
4.3.3 Surface quality
Fig.28 (a) Surface roughness for six operating conditions; (b) dry, (c) PMQL, (d) GMQL with lower cutting fluid concentration, (e) GMQL with appropriate cutting fluid concentration, (f) GMQL with higher cutting fluid concentration [106]. GMQL: graphene minimum quantity lubrication; PMQL: pure minimum quantity lubrication. Reproduced with permission from Elsevier. |
Fig.29 Scanning electron microscope images of the surface of specimens processed under different conditions [50]: (a) graphene nanoparticle-enhanced coolant, (b) cooling based on synthetic cutting fluid, (c) pure rapeseed oil-based minimum quantity lubrication, and (d) dry grinding. Reproduced with permission from Elsevier. |
4.4 Application effects
Tab.5 NPEC processing properties |
References | Cutting fluid | Working condition | Conclusion (compared with MQL) |
---|---|---|---|
[115,200] | Canola oil + GNP | Turning | COF: ↓ 16%‒39%, Ra: ↓ 41%–53%, cutting temperature: ↓ 50.53 °C |
[206] | Vegetable oil + MWCNTs | Turning | Energy consumption: ↓ 11.5%, tool wear: ↓ 45% |
[204] | Canola oil + GNP | Turning | Tool life: ↑ 50%, tool wear: ↓ 60% |
[209] | Vegetable oil + Al‒GNP | Turning | Energy consumption: ↓ 1.5%, surface quality: ↑ 11%‒15.7% |
[192] | Distilled water + Al2O3‒CNT | Turning | Ra: ↓ 8.72%, tool life: ↑ 23% |
[207] | Soybean + GNP | Turning | Tool wear: ↓ 20% |
[205] | Vegetable oil + GNP | Turning | Surface quality: ↑ 36% |
[210] | Jojoba oil + MoS2 | Turning | Ra: ↓ 34.56%, tool wear: ↓ 16% |
[235] | Cottonseed oil + Al2O3 etc. | Milling | Ra: Al2O3 < SiO2< MoS2 < CNTs < graphite < SiC |
[236] | Vegetable oil + CuO/GNP | Milling | (CuO) Ra: ↓ 14.7%, (GNP) Ra: ↓ 21.96% |
[59,218] | Vegetable oil + GNP | Milling | Ra: ↓ 17.45%, tool wear: ↓ 5.9% |
[214] | Cottonseed oil + Al2O3 | Milling | Ra: ↓ 66.7% |
[215] | Olive oil + Fe3O4 | Milling | Ra: ↓27.75%, tool wear: ↓ 63.3% |
[35] | Distilled water + Al2O3 | Milling | COF: ↓ 53.9% |
[208] | Water + MWCNTs | Milling | Ra: ↓ 27%, tool wear: ↓ 34% |
[171] | Vegetable oil + carbon onion | Milling | Ra: ↓ 46.32% |
[237] | Cottonseed oil + Al2O3 | Milling | Ra: ↓ 48.12% |
[238] | Vegetable oil + HBN | Milling | Ra: ↓ 8.2%, milling temperature: ↓ 4.7%, tool wear: ↓ 5.4% |
[50] | Canola oil + GNP | Grinding | Ra: ↓ 16.9%, specific grinding energy: ↓ 33.83% |
[129] | Palm oil + GNP | Grinding | COF: ↓ 71.2% |
[226] | Castor oil + CNT | Grinding | Cutting temperature: ↓ 32°C |
[239] | Canola oil + GNP | Grinding | Specific grinding energy: ↓ 15.7%, Ra: ↓ 36.4%, COF: ↓ 40.9% |
[106] | Vegetable oil + GNP | Grinding | Grinding temperature: ↓ 16.3%, specific grinding energy: ↓ 24.4%, Ra: ↓ 23.4% |
[233] | Water + Al2O3−CuO | Grinding | Ra: ↓ 18% |
[231] | Palm oil + GNP | Grinding | Specific grinding energy: ↓ 80.3% |
[208] | Water + MWCNTs | Grinding | Tool wear: ↓ 34% |