2019-VIT 9-Cutting Fluids-Rao.pptx

Sustainable Manufacturing
- Cutting Fluids
Dr. Julie Zhang
Dr. P. N. Rao
Department of Technology

Presentation Outline
October 24, 2023 2
Cutting Fluids Requirements and problems
Vegetable cutting fluids
Minimum Quantity Lubrication (MQL)
Conclusions
1
2
3
4

3
Implementing Sustainable
Manufacturing
Raw Material
Substitution
Shifting to more
environmentally
sound inputs
“Government Strategies and Policies for Cleaner Production.” United Nations Environmental Programme and “Eco-Innovation
in Industry: Enabling Green Growth” OECD
Generally easier More Difficult
October 24, 2023

Cutting Fluids
Coolants
Metal Working Fluids
24-Oct-23 4

Cutting Fluids
• Cools the cutting tool, workpiece and chip by
removing heat.
• Lubricates the chip tool and tool work
interfaces by reducing friction.
• Auxiliary functions such as chip removal, rust
inhibition, etc. are also important.
October 24, 2023 8
http://www.carlube.co.uk/images/products/sliders/hydraul
ic-cutting-fluids/Gallery-cutting-fluid-1-42084307.jpg

Cutting Fluids
• Enhances the machining quality while reducing
the cost of machining (power, reworking, scrap
costs).
• A large variety of cutting fluids based on
organic and inorganic materials have been
developed.
October 24, 2023 9
http://www.carlube.co.uk/images/products/sliders/hydraul
ic-cutting-fluids/Gallery-cutting-fluid-1-42084307.jpg

During Machining
• High temperature is
generated at interfaces (tool
work &tool chip)
 due to metal
deformation
 chip friction at the tool
chip interface.
• Increased cutting tool
wear→ Reduced tool life
• Large cutting forces & poor
surface finish
• Reduced productivity
• Increased product cost
• Remedy:
Use of cutting fluids
• Effect:
• Improves the efficacy of
machining process by
• Reducing generated
temperature
• Reducing tool wear
• Flushing away chips
• Reducing thermal
deformation of
workpiece
October 24, 2023 10

Cutting Fluid Function
• Grinding
• Turning
• Milling
• Drilling
• Reaming
• Boring
• Gear cutting
• Thread cutting
• Broaching
24-Oct-23 11
Increasing
Lubrication
effect
Increasing
Cooling
effect

Cutting Fluids
Oil based
Mineral oils Animal Oils Vegetable oils
Gas based Water based
Solution
(water in oil)
Synthetic
cutting fluids
Emulsion (oil
in water)
Semi-
synthetic
cutting fluids
24-Oct-23 12

October 24, 2023 13
Brinksmeier, E., Meyer, D., Huesmann-Cordes, A. G., & Herrmann, C. (2015). Metalworking fluids—Mechanisms and
performance. CIRP Annals-Manufacturing Technology, 64(2), 605-628. http://dx.doi.org/10.1016/j.cirp.2015.05.003

Cutting Fluid Additives
• Extreme Pressure (EP)
• Anti wear (AW)
• Friction modifier
• Emulsifiers
• Biocides
• Corrosion inhibitors
• Anti-foam
• Anti-fogging
October 24, 2023 14

October 24, 2023 15
Brinksmeier, E., Meyer, D., Huesmann-Cordes, A. G., & Herrmann, C. (2015). Metalworking fluids—Mechanisms and
performance. CIRP Annals-Manufacturing Technology, 64(2), 605-628. http://dx.doi.org/10.1016/j.cirp.2015.05.003

October 24, 2023 16
Brinksmeier,
E.,
Meyer,
D.,
Huesmann-Cordes,
A.
G.,
&
Herrmann,
C.
(2015).
Metalworking
fluids—Mechanisms
and
performance.
CIRP
Annals-Manufacturing
Technology,
64(2),
605-
628.
http://dx.doi.org/10.1016/j.cirp.2015.05.003

Cutting Fluids
• In 2002, over 2 billion gallons of cutting fluids
were used by North American manufacturers.
• In Germany, coolant consumption is about
75,500 tons a year (c 1996)
• In Japan, cost of purchasing coolant is about
29 billion Japanese Yen a year, in Japan’s
Cutting fluid cost (estimated 71 billion Yen) in
1984.
24-Oct-23 17
Adler, D. P., Hii, W. S., Michalek, D. J., & Sutherland, J. W. (2006). Examining the role of cutting fluids in machining and efforts to
address associated environmental/health concerns. Machining Science and technology, 10(1), 23-58.

Cutting Fluids - Problems
• Cutting fluids are highly vulnerable to
microbial contamination (Pseudomonas
Genus)
• It feeds on hydrocarbons in the oil and can
break down the ingredients of cutting fluid.
• Not completely controlled even by biocides
24-Oct-23 18

Air Quality Issues with Cutting Fluids
October 24, 2023 19
Sutherland, J. (2015) Design and Manufacturing for Sustainability, 2015 ASME International
Mechanical Engineering Education Leadership summit, Newport Beach, CA, USA.

Air Quality Issues with Cutting Fluids
October 24, 2023 20
Sutherland, J. (2015) Design and Manufacturing for Sustainability, 2015 ASME International
Mechanical Engineering Education Leadership summit, Newport Beach, CA, USA.
Cutting Fluid Mist – A
Potential Worker
Inhalation Health
Hazard

Cutting Fluids
• The mist and vapor generated is harmful
for the operator (lung diseases).
• Direct exposure of cutting fluids has been
responsible for a number of skin cancer
cases.
• Often looked upon as an additional cost
October 24, 2023 21

Cutting Fluids - Health Issues
• Several large outbreaks of respiratory disease
in car component factories using
metalworking fluids have been reported in the
United States.
• These outbreaks have shown a spectrum of
disease including hypersensitivity pneumonitis
(HP) known in the UK as extrinsic allergic
alveolitis (EAA), occupational asthma (OA) and
work – related bronchitis.
October 24, 2023 22
http://www.hse.gov.uk/metalworking/experience/powertrain.pdf

• Outbreak of respiratory disease at Powertrain Ltd,
Longbridge, Birmingham
– By March 2006, 101 cases of probable and definite work
related respiratory disease (excluding occupational
bronchitis) had been identified among workers.
– Among these, there were 87 cases of occupational asthma
(OA) and 24 cases of extrinsic allergic alveolitis (EAA).
– Some workers were diagnosed with more than one
disease.
– It is thought these represent the world’s largest recorded
outbreak of occupational respiratory disease linked to
metalworking and wash fluids.
October 24, 2023 23

• Respiratory disease from metalworking fluids has
been linked to:
– the constituents of the fluids themselves, and
additives,
– bacteria in the fluids (particularly mycobacteria, which
are related to bacteria which cause tuberculosis, but
are not infectious in the same way),
– endotoxins (released from dead bacteria, sometimes
arising from biocides used to kill bacteria),
– formaldehyde (a by product of some biocides),
– the metals involved, such as cobalt, and
– fungi in the metalworking fluids.
October 24, 2023 24

Recycling Cutting Fluids
• A number of methods and equipment are
available for the recycling of cutting fluids,
including skimmers, coalescers, centrifuges,
settling tanks, magnetic separators and
filtration systems.
• Skimmers are used to remove tramp oil, which
is a contaminated portion of the cutting fluid.
– The tramp oil floats to the top and is pushed off
using a collection belt.
October 24, 2023 25

Recycling Cutting Fluids
• Coalescers and centrifuges can also remove
tramp oil as well as solid contaminants.
– Coalescers promote the fusing together of the tramp
oil into larger droplets, which will then naturally rise
to the top of the surface more rapidly to be skimmed
off.
– Centrifuges spin the fluid to generate gravitational
forces and help separate solids and tramp oil from the
normal cutting fluid.
• Settling tanks, magnetic separators and filtration
systems can remove solid contaminants to
varying degrees and efficiencies.
October 24, 2023 26

Cutting Fluid recycling contaminant
removal equipment
October 24, 2023 27
I. W. R. C. (2003). Cutting fluid management for small machining operations. A
Practical Pollution Prevention Guide, 3.:
https://iwrc.uni.edu/sites/default/files/CuttingFluidManagement.pdf

Cutting Fluids
• After several uses and reclamation cycles,
eventually the cutting fluid is destined for
disposal.
• Proper disposal techniques necessary to
preserve soil and water bodies.
• Should be recycled or disposed of in a manner
that is not harmful to the environment as
specified by the environmental agencies of the
nation (EPA in USA).
October 24, 2023 28

Cutting Fluids
• Cutting fluid consumption is estimated higher
than 100 million gallons per year in U.S.
– The cost of purchasing and disposing cutting fluid
is about 48 billion dollars a year
• In 2002, over 2 billion gallons of cutting fluids
were used by North American manufacturers.
October 24, 2023 29
Adler, D. P., Hii, W. S., Michalek, D. J., & Sutherland, J. W. (2006). Examining the role of cutting fluids in
machining and efforts to address associated environmental/health concerns. Machining Science and
technology, 10(1), 23-58.

Metalworking Fluids
• Global demand for metalworking fluids in
2012 was estimated at 2.2 million tons.
• Europe, which includes Western, Central and
Eastern Europe, Russia and Turkey, accounts
for 26 percent of the total.
• Asia is the largest market with about 42
percent of the total demand, followed by
North America with 28 percent.
October 24, 2023 30
http://www.lubrita.com/news/191/671/Global-demand-for-metalworking-fluids/

Cutting Fluids
• In Germany, coolant consumption is
about 75,500 tons/ year
–The cost of purchasing and disposing
coolant is about one billion German Mark
• Estimated coolant disposal cost in Japan is
about 42 billion Yen.
October 24, 2023 31

U.S. metalworking fluids market volume, by
product, 2012 - 2022 (Kilo Tons)
October 24, 2023 32
http://www.grandviewresearch.com/industry-analysis/metalworking-fluids-market

Machining, 14.8
Oil pressure
pump, 24.4
Coolant, 31.8
Cooler, mist
collector, etc,
15.2
Centrifuge,
10.8
Energy breakdown % for Machining
(Courtesy Toyota Motor Corp)
October 24, 2023 33
Dahmus, J., & Gutowski, T. (2004, November). An environmental analysis of machining. In ASME
International Mechanical Engineering Congress and RD&D Exposition, Anaheim, California, USA.

Cutting Fluids
• Cutting fluids cost 7-17% of the manufacturing
cost in German automotive industry
compared to tool costs that are quoted as
being 2 – 4%.
• Disposal costs, recirculation costs form a
major share of the cost
October 24, 2023 34

Cutting Fluids - Solutions
24-Oct-23 35
Petroleum
based
cutting
fluids,
Flooding
Minimum
Quantity
Lubrication
Vegetable
based cutting
fluids
Use nano
particles
Dry cutting
Present
Status

36
Implementing Sustainable
Manufacturing
Raw Material
Substitution
Shifting to more
environmentally
sound inputs
“Government Strategies and Policies for Cleaner Production.” United Nations Environmental Programme and “Eco-Innovation
in Industry: Enabling Green Growth” OECD
Generally easier More Difficult
October 24, 2023
Better handling
of MWF
Use MQL
Use Vegetable
cutting fluids
Use Nano
cutting fluids
MQL with nano
fluids

Flooding
• Typically, flow rate of over 100 L/h is adopted.
• The cooling is mainly due to conduction and
convection of the heat from the machining
zone by the flowing cutting fluid and a small
quantity of the coolant may reach the
tool/chip interface, depending on the
direction of the coolant application.
• Mostly water soluble fluids are used.
24-Oct-23 37

Flooding
24-Oct-23 38
http://news.cision.com/q8oils/i/q8-cutting-fluids-are-being-
used-to-machine-316l-stainless-steel,c1413363

Flooding
• It was reported that cutting speeds of 3.33
m/s (200 m/min) were possible in flood
lubrication using diamond tools.
• Though flood lubrication is usually sufficient
for effective cooling in machining of titanium
alloys, high-pressure coolant delivery systems
are preferred.
24-Oct-23 39

Surface roughness in different lubricating
conditions [Ezugwu et al. (2007)]
24-Oct-23 40

Cutting temperatures at different coolant
pressures [Hadzley et al. 2013]
24-Oct-23 41

Flooding
• No extra
setup or
device is
needed.
• Only cools the machining zone up to a
certain extent.
• Poor lubrication. It cannot effectively
penetrate the tool-work interface due to
bigger fluid droplets size.
• Shorter tool life and frequent tool wear.
• Higher power consumption.
• Higher consumption of cutting fluid.
• Emits particulates, fumes and gases
harmful for the health of the operator.
24-Oct-23 42

Flood application of cutting fluid
Disadvantages:
 Properties degrade with time. So,
maintenance required.
 When maintenance becomes
uneconomical, disposal to
environment.
 Disposal of untreated cutting fluid
creates imbalance in ecosystem in
water bodies due to
◦ hazardous metal carry-off
◦ hazardous chemical composition,
◦ depletion of oxygen
◦ excessive nutrient loading
 Treatment and Disposal – Costly
(MWFs – Hazardous waste)
October 24, 2023 43

MINIMUM QUANTITY LUBRICATION
(MQL)
October 24, 2023 44

• The goal of MQL is to use just enough coolant
and lubricant to minimize friction and heat.
• The use of cutting fluids of only a minute
amount- typically of a flow rate of 50 to 500
mL/hour.
• 120 L/hour (120 000 mL/hour) is commonly
used in flood cooling condition.
24-Oct-23 45

A schematic showing various components
of a typical MQL system
24-Oct-23 46
Gupta, K., & Laubscher, R. F. (2017). Sustainable machining of titanium alloys: a critical
review. Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering
Manufacture, 231(14), 2543-2560.

Typical MQL system
24-Oct-23 47
https://www.youtube.com/watch?v=uoqDMPzSyGU

Minimum Quantity Lubrication(MQL)
• Small Quantity of coolant/
lubricant is mixed with
compressed air and applied at
cutting zone,
• vaporizes completely at high
temperature,
• forms a film that prevents the
workpiece from corrosion, and
• Prevents the need of disposal
• As small quantities of cutting
fluid is used, cutting fluid with
superior qualities than
conventional cutting fluid is
required.
October 24, 2023 49
http://hdxoil.com.br/wp-
content/uploads/2013/03/DK_mql.jpg

• The goal of MQL is to use just enough coolant
and lubricant to minimize friction and heat.
• The use of cutting fluids of only a minute
amount- typically of a flow rate of 50 to 500
mL/hour.
• 120 L/hour commonly used in flood cooling
condition.
October 24, 2023 50

• Large surface to volume ratio for each drop
provides the possibility of rapid vaporization,
which is an important step that must precede
penetration of the chip tool interface.
• The small size of the particles in the mist
improves the penetrating ability of the cutting
fluids.
October 24, 2023 51

• External
October 24, 2023 53

• Internal
October 24, 2023 54

MQL - Internal
• Advantages
• Optimal lubrication at
the tool point
• No scattering or spray
losses
• Optimized lubricant
quantity for each tool
• Disadvantages
• Special tools required
• High investment costs
• Suitable machine
required
October 24, 2023 55

MQL - External
• Advantages
• Simple adaptation
• Low investment costs
• Little work required to
retrofit existing
machines
• No special tools
required
• Disadvantages
• Limited adjustment
options for tools
because of the different
lengths and diameters
October 24, 2023 56

October 24, 2023 58
Jun, M. B., Joshi, S. S., DeVor, R. E., & Kapoor, S. G. (2008). An experimental evaluation of an atomization-based
cutting fluid application system for micromachining. Journal of manufacturing science and engineering, 130(3),
031118.

1-Channel MQL System
October 24, 2023 59

2-Channel MQL System
October 24, 2023 60

• The diameter of the aerosol particulates, must be
within tight tolerances for optimum wetting and
lubrication.
• In CNC machines designed for MQL, the software for
a specific part controls the amount and duration of
aerosol spray.
• Milling, is a surface operation and requires a
minimum amount of lubricity. But tapping and
thread cutting call for much more because of the
high surface pressures involved.
October 24, 2023 62

• Chips produced with the MQL system remain
essentially dry, so time-consuming and costly
coolant-recovery operations are unnecessary.
• MQL machining reduces costs and protects the
environment.
• As long as the mixing and dispersion of oil is precisely
controlled, part quality remains as good as or better
than wet machining processes.
October 24, 2023 63

SME – MQL Video
October 24, 2023 64
https://www.youtube.com/watch?v=uoqDMPzSyGU

MMS- Getting Started With Minimum
Quantity Lubrication
October 24, 2023 65
https://www.youtube.com/watch?v=xLJgM47kNow

Unist: What is Minimum Quantity
Lubrication (MQL)
October 24, 2023 66
https://www.youtube.com/watch?v=aP3glc4HoWg

MQL - Type of Cutting Fluid
• Cutting fluids with very good lubricity and high
flash point to reduce the mist formation are
preferred.
• Synthetic esters are generally used.
• No water soluble oils – Neat oils are preferred
• Low viscosity – good for atomization
• High flash point – low mist generation
• Biodegradable
24-Oct-23 67

MQL – Operating Conditions
• Cutting fluids used in MQL will have practical
viscosity range of 15 to 50 mm2/s and in some
cases up to 100 mm2/s at 40°C.
• 6 bar pressure for most operations
• 12 to 14 bar for deep hole drilling
• MQL performance displays an optimum
amount of fluid consumption which varies
with the operation. Typical is 10 to 30 mL/h
24-Oct-23 68

October 24, 2023 69
Dhar, N. R., Kamruzzaman, M., & Ahmed, M. (2006). Effect of minimum quantity
lubrication (MQL) on tool wear and surface roughness in turning AISI-4340
steel. Journal of materials processing technology, 172(2), 299-304.

• Dhar et al (2006) used MQL for turning AISI
4340 steel.
• MQL supply- Air: 7.0 bar, lubricant: 60 ml/h
(through external nozzle)
• Lesser tool wear and surface roughness were
reported
October 24, 2023 70

October 24, 2023 71

October 24, 2023 72

• Li et al (2010) applied MQL in micro milling
with two different tools
• MQL conditions- Lubricant supply-1.8 ml/hr,
Air supply-40 l/hr
• Decreased tool wear compared to dry
machining
October 24, 2023 73
Kuan-Ming Li, Shih-Yen Chou (2010), Experimental evaluation of minimum
quantity lubrication in near micro-milling, Journal of Materials Processing
Technology, 210, 2163–2170.

October 24, 2023 74
Kuan-Ming Li, Shih-Yen Chou (2010), Experimental evaluation of minimum
quantity lubrication in near micro-milling, Journal of Materials Processing
Technology, 210, 2163–2170.

• Ford Motor Company has a total of over 400
MQL CNC machining centers in its global
transmission and engine plants that are
utilizing MQL operations.
October 24, 2023 75

• MQL can provide superior lubrication but does
not have sufficient cooling similar to flooding.
• Better lubrication - friction is reduced – Heat
generated is reduced
• Flushing of chips would be a problem if the
compressed air is not properly directed in the
cutting zone.
October 24, 2023 76

Successful mass-produced automobile
parts using MQL
Component Material Process Tool life Medium, chem. base,
Viscosity 40°C
Camshaft 16MnCr5 Drilling 2 400 holes Fatty alcohol
Visc: 10 – 20 mm2/s
Camshaft 16MnCr5 Reaming 1 200 operations Fatty alcohol
Visc: 10 – 20 mm2/s
Crankshaft 38MnVS5 Drilling 500 holes Fatty alcohol
Visc: 20 mm2/s
Crankshaft 38MnVS5 Countersinking 960 operations Fatty alcohol
Visc: 20 mm2/s
Crankcase Al Si9
Cu3
Deep hole
drilling
5 000 holes Synthetic ester
Visc: 40 – 50 mm2/s
Universal
joints
CK 45 Drilling
(Impact drilling)
100 – 150 holes Synthetic ester
Visc: 20 – 30 mm2/s
October 24, 2023 77
Rao, P. N. (2015) Minimum Quantity Lubrication An approach for sustainable manufacturing,
Efficient Manufacturing, India. July, pp 20 – 26.

Experimental results of various drilling
operations using MQL
Material Cutting fluid MQL Parameters Year Cutting process
improvement
Aluminium alloy ACP
5080, BHN 85
Vegetable oil 20 mL/h, 6 bar pressure 2002 Surface finish
improved.
Aluminum silicon
alloy, A 356
Soluble oil 10 mL/h, 4.5 bar
pressure, Air flow 72
m3/h
2002 Better quality than
flooding
Ti6Al4V Emulsion
above 3.5%
concentration
50 mL/h, 3.5 bar,
Internal and external
2006 Temperature 50% less
for internal compared
to external nozzle
AISI 1045 steel Synthetic
ester
18 mL/h, external 2006 Increased tool life
with MQL
Cast B319 (Al-base,
Si-5.5-6.5, Cu 3-4, Fe,
Mg, Ni—less
than 1 wt.%)
Commonweal
th oil
100 psi, 2008 MQL comparable to
wet machining
October 24, 2023 78

VEGETABLE OILS
October 24, 2023 79

Vegetable Oils
• Conventional mineral oil can be replaced using
vegetable oils
• Vegetable oils can substitute petroleum-based
oils because they are environmentally friendly,
renewable, less toxic and readily
biodegradable.
• Vegetable oils provide adequate lubrication
through production of a high strength film
between the surfaces.
October 24, 2023 80
Shashidhara, Y. M., & Jayaram, S. R. (2010). Vegetable oils as a potential
cutting fluid—an evolution. Tribology International, 43(5), 1073-1081.

Metal Working Fluids
24-Oct-23 81
Types of fluid Biodegradability (%)
Mineral Oil 20-30
Vegetable oil 95-98
Esters 75-100
Polyols 75-100

Vegetable Oils
October 24, 2023 82
Shashidhara, Y. M., & Jayaram, S. R. (2010). Vegetable oils as a potential cutting
fluid—an evolution. Tribology International, 43(5), 1073-1081.
Properties Soybean Sunﬂower Rapeseed Jatropha Neem Castor
Kinematic
viscosity @
40°C (cSt)
32.93 40.05 45.6 47.48 68.03 220.6
Kinematic
viscosity @
100°C (cSt)
8.08 8.65 10.07 8.04 10.14 19.72
Viscosity index 219 206 216 208 135 220
Pour point
(0°C)
-9 -12 -12 0 9 -27
Flash point
(0°C)
240 252 240 240 – 250

Vegetable Oils
October 24, 2023 83
Canola oil
Hydraulic oils, tractor transmission fluids, metal
working fluids, food grade lubes
Castor oil Gear lubricants, greases
Coconut oil Gas engine oils
Rapeseed oil
Chain saw bar lubricants, air compressor-farm
equipment, Biodegradable greases.
Sunflower oil Grease, diesel fuel substitutes
Linseed oil Coating, paints, lacquers, varnishes, stains,
Soybean oil
Lubricants, biodiesel fuel, metal casting/working,
printing inks, paints, coatings, soaps, shampoos,
detergents, pesticides, disinfectants, plasticizers,
hydraulic oil

Vegetable Oils
October 24, 2023 84
Advantages (required qualities of metal
working ﬂuids)
Disadvantages
High biodegradability Low thermal stability
Low pollution of the environment, Oxidative stability
Compatibility with additives High freezing points
Low production cost
Poor corrosion
protection
Wide production possibilities
Low toxicity
High ﬂash points
Low volatility
High viscosity indices

Wang, Y., Li, C., Zhang, Y., Yang, M., Li, B., Jia, D., ... & Mao, C. (2016). Experimental evaluation of the lubrication
properties of the wheel/workpiece interface in minimum quantity lubrication (MQL) grinding using different types of
vegetable oils. Journal of Cleaner Production, 127, 487-499.; http://dx.doi.org/10.1016/j.jclepro.2016.03.121
Friction coefficient of different
lubrication conditions
October 24, 2023 85

Specific grinding energy of different
lubrication conditions
October 24, 2023 86
Wang, Y., Li, C., Zhang, Y., Yang, M., Li, B., Jia, D., ... & Mao, C. (2016). Experimental evaluation of the lubrication
properties of the wheel/workpiece interface in minimum quantity lubrication (MQL) grinding using different types of
vegetable oils. Journal of Cleaner Production, 127, 487-499.; http://dx.doi.org/10.1016/j.jclepro.2016.03.121

Vegetable oils
• Petroleum-based cutting fluids generate mist
due to heat at tool-workpiece interface
because of their low flash point (about 215°C).
• Soybean-based cutting fluids reduce mist
generation because of high molecular weight
and high flash point of around 315°C .
October 24, 2023 87

Dry and MQL machining of Ti6Al4V, Flow rate
of 16 mL/h
24-Oct-23 88
Liu Z, An Q, Xu J, Chen M, Han S (2013) Wear performance of (nc-AlTiN)/(a-Si 3N 4)
coating and (nc-AlCrN)/(a-Si 3N 4) coating in high-speed machining of titanium alloys
under dry and minimum quantity lubrication (MQL) conditions. Wear 305(1): 249–259
Uncoated (R1)
nc-AlTiN/a-Si3N4 (R2)
nc-AlCrN/a-Si3N4 (R3)
cutting speed 120 m/min,
feed rate - 0.1 mm/rev,
depth of cut - 1.2 mm.

Vegetable oils
• Cutting temperatures, forces and tool wear
are greatly reduced.
• Used in 2 forms- neat oils or water miscible
oils
October 24, 2023 89

October 24, 2023 90
Lawal S A, Choudhury I A, Nukman Y, Application of vegetable oil-based
metalworking fluids in machining ferrous metals—A review, International Journal
of Machine Tools and Manufacture, 52(1), 1-12, 2011.
AISI 304 Stainless steel

October 24, 2023 91
AISI 1040 Steel

October 24, 2023 92
AISI 1040 Steel

Vegetable Oils
October 24, 2023 93
Lawal S A, Choudhury I A, Nukman Y, Application of vegetable oil-based metalworking
fluids in machining ferrous metals—A review, International Journal of Machine Tools and
Manufacture, 52(1), 1-12, 2011.

Life Cycle Emissions of Bio- and
Petroleum MWFs
• Table 1 details the compositions of the
petroleum and rapeseed oil MWFs considered
in the life cycle assessment.
• The functional unit was one year of machining
time assuming that the functionality of the
two MWFs was identical and that the
formulations were equally stable during
recirculation.
October 24, 2023 94
Skerlos, S. J., Hayes, K. F., Clarens, A. F., & Zhao, F. (2008). Current advances in sustainable metalworking
fluids research. International Journal of Sustainable Manufacturing, 1(1-2), 180-202.

October 24, 2023 95

Petroleum MWFs
• Figure 4 compares the material production impacts broken
down by component. The results suggest that surfactants
dominate the emissions for four of the eight impact
categories: GWP, acidification, energy, and solid waste.
• The rapeseed oil-in-water formulation has slightly lower
GWP and acidification potential but requires more energy
and land/pesticide use, while creating more solid waste.
• The need for surfactants in both water-based systems
means that although modest tradeoffs exist between
petroleum- and bio-based fluids, neither system has a
significantly lower impact than the other.
October 24, 2023 96

October 24, 2023 97

Petroleum MWFs
• A move away from water-based emulsion
systems to gas-based MQL systems would be a
much stronger move towards sustainability than
a mere switch in feedstock from petroleum to bio
within a water-based MWF.
• On the other hand, at the current time MQL
alternatives to water-based MWFs do not exist
for many advanced manufacturing applications.
• This calls for research into new MQL technologies
capable of performing well in severe
manufacturing conditions.
October 24, 2023 98

MQL WITH VEGETABLE OILS
October 24, 2023 100

MQL with Vegetable oils
• Conventional mineral oil replaced using
vegetable oils
• Provide adequate lubrication through
production of a high strength film between
the surfaces
• Petroleum-based cutting fluids generate mist
due to heat at tool-workpiece interface
because of their low flash point (about 215°C).
October 24, 2023 101

• Soybean-based cutting fluids reduce mist
generation because of high molecular weight
and high flash point of around 315°C
• Cutting temperatures, forces and tool wear
are greatly reduced.
• Used in 2 forms- neat oils or water miscible
oils
October 24, 2023 102

• Two types of vegetable oils viz. Karanja oil and
Neem oil have been used to measure
temperature effect and Compared with
regular cutting fluid
• Surface finish has improved.
• Temperature is reduced compared to dry but
more compared to conventional fluid.
October 24, 2023 103
Paul, S., & Pal, P. K. (2011). Study of surface quality during high speed machining
using eco-friendly cutting fluid. Mach Technol Mater, 11, 24-28.

October 24, 2023 104
Paul, S., & Pal, P. K. (2011). Study of surface quality during high speed machining using
eco-friendly cutting fluid. Mach Technol Mater, 11, 24-28.

October 24, 2023 105
Paul, S., & Pal, P. K. (2011). Study of surface quality during high speed machining using eco-friendly
cutting fluid. Mach Technol Mater, 11, 24-28.

• Talib and Rahim (2015) modified jatropha oil
• Tested viscosity, density and tribology as per
ASTM
• Used the fluids in MQL and compared with
synthetic fluids.
• Reduced cutting forces were reported
October 24, 2023 106
Talib, N., & Rahim, E. A. (2015). Performance Evaluation of Chemically Modified Crude Jatropha Oil as a Bio-based
Metalworking Fluids for Machining Process. Procedia CIRP, 26, 346-350.

CJO- Crude Jatropha oil, SE- Synthetic
esters, MJO- Modified Jatropha oil
October 24, 2023 107
Talib, N., & Rahim, E. A. (2015). Performance Evaluation of Chemically Modified Crude Jatropha Oil as a Bio-based
Metalworking Fluids for Machining Process. Procedia CIRP, 26, 346-350.

MQL in Grinding
• Li et al. (2016) tested different vegetable oils
as lubricants for MQL in grinding
• Castor oil produced lowest grinding force
• Viscosity found to be an influential factor
October 24, 2023 108
Li, B., Li, C., Zhang, Y., Wang, Y., Jia, D., & Yang, M. (2016). Grinding temperature and energy
ratio coefficient in MQL grinding of high-temperature nickel-base alloy by using different
vegetable oils as base oil. Chinese Journal of Aeronautics. Volume 29, Issue 4, 2016, 1084–1095

Grinding temperature of the seven kinds of
vegetable oils in MQL grinding
October 24, 2023 109
Li, B., Li, C., Zhang, Y., Wang, Y., Jia, D., & Yang, M. (2016). Grinding temperature and energy
ratio coefficient in MQL grinding of high-temperature nickel-base alloy by using different
vegetable oils as base oil. Chinese Journal of Aeronautics. Volume 29, Issue 4, 2016, 1084–1095

24-Oct-23 111
Petroleum
based
cutting
fluids,
Flooding
Minimum
Quantity
Lubrication
Vegetable
based cutting
fluids
Use nano
particles
Dry cutting
Present
Status

Nano-fluids
• MQL lubricates the machining zone but may
not cool it adequately
• Fluids with enhanced thermal transportation
properties are desired
• It is observed that thermal conductivity and
convection heat transfer coefficient of a fluid
can be greatly increased by inclusion of
nanoparticles
24-Oct-23 112

Nano-fluids
• Nanofluids are engineered colloidal
suspensions of nanoparticles (1-100 nm) in a
base fluid
• Various nano particles like metals, oxides or
carbon (CNTs, graphite, etc.) are used
• Hydrophobic particles (e.g. Graphite) are
functionalized before dispersion in aqueous
fluid
• Dispersed using a sonicator
24-Oct-23 113

Conclusions
• Cutting fluids is one area in machining that is
currently not truly sustainable
• Cutting fluids popularly used in machining to
improve the performance
• Maintenance and disposal of cutting problem
is a serious problem
• MQL is a potential solution for problems with
cutting fluids
October 24, 2023 114

Nano-fluids
• Funtionalization method depends on
nanoparticles
• For graphite, nanoparticles are treated with
H2SO4 and HNO3 for 6 hr.
• Mixture is cleaned with water to bring the pH
of nanoparticles to 7.
• Dried in vacuum oven at 800°C for 16 hours to
obtain functionalized nanoparticles
24-Oct-23 115

Nano-fluids
• Stability of nanofluid is critical for its
performance
• Evaluated using zeta potential
24-Oct-23 116
Zeta Potential value Stability
0 to ±30 Unstable
±30 to ±40 Moderate
±40 to ±60 Good
> ± 60 Excellent
72

Nano-fluids
• Nanofluids are characterized to ensure
uniform dispersion and hence uniform
properties.
• Formulated fluids are generally tested to find
the thermal conductivities and other
properties
• General rules like law of mixtures for thermal
conductivity do not hold good for nanofluids
24-Oct-23 117

24-Oct-23 118
Particle Base fluid
Average
particle size
Volume
fraction
Thermal
conductivity
enhancement
Metallic
nano-fluids
Cu Water 100 nm 7.50% 78%
Au Water 10–20 nm 0.03% 21%
Ag Water 60–80 nm 0.00% 17%
Non-
metallic
nano-fluids
Al2O3 Water 13 nm 4.30% 30%
Al2O3 Water 33 nm 4.30% 15%
Al2O3 Water 68 nm 5% 21%
CuO Water 36 nm 3.40% 12%
CuO Water 50 nm 0.40% 17%
SiC Water 26 nm 4.20% 16%
TiO2 Water 15 nm 5% 30%
MWCNT Synthetic oil
25 nm in
diameter 50
μm in length 1% 150%
MWCNT Water
100 nm in
diameter 70
μm in length 0.60% 38%

MQL with Nano-fluids
• Lee et al. (2010) applied nanofluid MQL in
grinding operation.
• Nanofluid- nano-diamond particles and paraffin
oil
• Reduced cutting forces compared to dry and MQL
with regular fluid
• Smaller sized particles are more effective
24-Oct-23 119
Lee, P. H., Nam, T. S., Li, C., & Lee, S. W. (2010, December). Environmentally-friendly
nano-fluid minimum quantity lubrication (MQL) meso-scale grinding process using
nano-diamond particles. In Manufacturing Automation (ICMA), 2010 International
Conference on (pp. 44-49). IEEE.

MQL with Nano-fluids
• It was observed that cutting force, surface
roughness, tool wear, and chip thickness
reduced with nanofluid (1% Al2O3) compared
to the conventional cutting fluid.
• Superior surface finish and tool life were
reported.
24-Oct-23 120
Khandekar, S., Sankar, M. R., Agnihotri, V., & Ramkumar, J. (2012). Nano-cutting
fluid for enhancement of metal cutting performance. Materials and Manufacturing
Processes, 27(9), 963-967.

24-Oct-23 121
Petroleum
based
cutting
fluids,
Flooding
Minimum
Quantity
Lubrication
Vegetable
based cutting
fluids
Use nano
particles
Dry cutting
Present
Status

Cutting with coated tools
• Electrostatic micro-solid lubricant (EMSL)
coating on carbide tool with molybdenum
disulfide (MoS2) as a solid lubricant.
• Tribological studies reveal that the EMSL
coating has the lowest friction coefficient on
average of about 50% less at all the sliding
conditions when compared to that of
uncoated one.
24-Oct-23 122

MoS2 Coated tools
24-Oct-23 123
Paturi, U. M. R., & Narala, S. K. R. (2015). Experimental investigation to study the effect of
electrostatic micro-solid lubricant–coated carbide tools on machinability parameters in
turning. Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering
Manufacture, 229(5), 693-702.

Cutting with coated tools
• Machining with EMSL coated cutting tools
results in lower frictional values at tool–work
interface leading to reasonable lower cutting
forces than those in machining with uncoated
cutting tools.
• Further, tool flank wear in EMSL coated
cutting tools is very less as compared to that
of the uncoated cutting tool.
24-Oct-23 124

Micro-texture at the coated tool face
for high performance cutting
• Textured surface on the rake face helps in
reducing the coefficient of friction, cutting
forces and chances of adhesion between chip
and cutting tool.
• The chemical etching process was used to
produce all these different types of designs.
24-Oct-23 125

Micro-texture at the coated tool face
for high performance cutting
24-Oct-23 126
Kawasegi, N., Sugimori, H., Morimoto, H., Morita, N., Hori, I., 2009.
Development of cutting tools with microscale and nanoscale textures to
improve frictional behavior. Precis. Eng. 33, 248e254.

24-Oct-23 127
Obikawa, T., Kamio, A., Takaoka, H., Osada, A., 2011. Micro-texture at the coated
tool face for high performance cutting. Int. J. Mach. Tools Manuf. 51, 966-972.

Groove Parameters
Parameters Dimensions in
microns
Width 25 to 50
Depth 0.5, 1.0 or 1.2
Distance from cutting
edge
100 to 150
24-Oct-23 128
Obikawa, T., Kamio, A., Takaoka, H., Osada, A., 2011. Micro-texture at the coated
tool face for high performance cutting. Int. J. Mach. Tools Manuf. 51, 966-972.

24-Oct-23 130
Titanium Machining
Sustainability
People Planet Profit
Vegetable
Fluids
Process
Optimization
Tool materials
Coatings
Green
Materials
Minimum Quantity
Lubrication

24-Oct-23 131
Li C, Tang Y, Cui L, Li P. A quantitative approach to analyze carbon emissions of CNC-based
machining systems. Journal of Intelligent Manufacturing. 2015 Oct 1;26(5):911-22.
CEtool
CEelec
CEchip
CEm
CEcoolant

Machining Carbon Foot Print
• CE = CEelec + CEtool + CEcoolant + CEm + CEchip
• CEelec = the carbon emissions due to production of
electricity necessary for machining,
• CEtool = the carbon emissions due to producing cutting
tools
• CEcoolant = the carbon emissions due to production of
cutting fluid,
• CEm = the carbon emissions due to production of raw
materials, and
• CEchip = the carbon emissions due to chip removal.
24-Oct-23 132

Carbon Emissions Due to Production
of Electricity
24-Oct-23 133
http://cea.nic.in/reports/others/thermal/tpece/cdm_co2/user_guide_ver10.pdf

Carbon Emissions Due to
Consumption of Electricity
• Electricity consumption factor in the machine
tool Pi can be identified into three parts:
• Standby power Pu,
• Cutting power Pc, and
• Additional load loss power Pa.
• Pi (t) = Pu(t) + Pc(t) + Pa(t).
24-Oct-23 134

Carbon Emissions Due to Actual
Consumption of Electricity
• ECmachine = Pu × (tidle + tc) + Pc × tc + Pa × tc
= Pu×tidle + Pi ×t c
• Pu and Pi can be obtained through power testing, and
tidle through historical data of the same or similar
mechanical components processed by the machine
tool.
• The cutting time tc is a function of cutting speed (v),
cutting depth (d), feed rate (f) , size, shape and
operation of the work piece.
24-Oct-23 135

of Cutting Fluid
• Assuming we are using water soluble oil
• The carbon emissions of cutting fluid is
comprised of two parts:
(1) the carbon emissions generated through the
production of pure mineral oil (CEoil); and
(2) the carbon emissions generated by the
disposal of cutting fluid waste (CEwc).
24-Oct-23 136

of Cutting Fluid
• To calculate CEoil , the carbon emissions generated
during the production of pure mineral oil are
distributed throughout the entire life cycle of cutting
fluid Tcoolant .
• CEoil accounts for the portion of the carbon emissions
when the tool is in use, either standby or in operation
• 𝐶𝐸𝑐𝑜𝑜𝑙𝑎𝑛𝑡 =
𝑇
𝑇𝑐𝑜𝑜𝑙𝑎𝑛𝑡
× 𝐶𝐸𝑜𝑖𝑙 + 𝐶𝐸𝑤𝑐
• T = tc + tidle
24-Oct-23 137

of Cutting Fluid
CEoil = CEFoil × (CC + AC)
𝐶𝐸𝑤𝑐 = 𝐶𝐸𝐹𝑤𝑐 ×
𝐶𝐶 + 𝐴𝐶
𝛿
• where CEFoil and CEFwc are the carbon
emission factors for the production of cutting
fluid and their disposal, respectively.
• CC is the initial volume of cutting fluid, AC is
additional volume of cutting fluid, and δ is the
predetermined cutting fluid concentration.
24-Oct-23 138

of Cutting Fluid
• The replacement period for the cutting fluid
Tcoolant depends upon the industry and practice.
• It is typically 2 to 3 months.
24-Oct-23 139

of Cutting Fluid
• The calculation of CEFoil typically maps the
embodied energy of the material of interest
(i.e., oily substance) to the corresponding
carbon content based on which the carbon
emissions are calculated.
𝐶𝐸𝐹𝑜𝑖𝑙 = 𝐸𝐸𝑜𝑖𝑙 × 𝐸𝐶𝑜𝑖𝑙 ×
44
12
24-Oct-23 140

of Cutting Fluid
• 𝐶𝐸𝐹𝑜𝑖𝑙 = 𝐸𝐸𝑜𝑖𝑙 × 𝐸𝐶𝑜𝑖𝑙 ×
44
12
• where EEoil is the embodied energy of mineral
oil and ECoil is the carbon intensity of mineral
oil.
• The unit of the former is GJ/L, and that of the
latter is kg C/GJ.
24-Oct-23 141

of Cutting Fluid
𝐶𝐸𝐹𝑜𝑖𝑙 = 𝐸𝐸𝑜𝑖𝑙 × 𝐸𝐶𝑜𝑖𝑙 ×
44
12
= 42.287 × 0.92 ×
44
12
= 2.85 kg CO2 /L
24-Oct-23 142

of Cutting Fluid
• Minimum Quantity Lubrication (MQL)
24-Oct-23 143

Carbon Emissions Due to Producing
Cutting Tools
• The calculation of CEtool is similar to that of
CEcoolant to account for the portion of the
carbon emissions when the tool is in operation.
𝐶𝐸𝑡𝑜𝑜𝑙 =
𝑡𝑐
𝑇𝑡𝑜𝑜𝑙
× 𝐶𝐸𝐹𝑡𝑜𝑜𝑙 × 𝑊𝑡𝑜𝑜𝑙
• CEFtool is the carbon emission factor of cutting tools,
• Wtool is the mass of the tool,
• Ttool is the life cycle of the tool, and
• tc is the cutting time.
24-Oct-23 144

Cutting Tools
CEFtool is related to the energy consumption of
cutting tools.
24-Oct-23 145

Cutting Tools
• A tool often gets sharpened N times in the
course of the life cycle.
• Each sharpening extends the tool life for tool
durability T0.
• Thus Ttool is calculated as follows:
Ttool = (N + 1)T0
• T0 can be calculated based on Taylor tool life
equation
24-Oct-23 146

of Raw Materials
• Only the carbon emissions caused by the
production of the removed material is counted
into the carbon emissions of the system
• CEm = CEFm × Mchip
• Where CEFm is the material carbon emission
factor and
• Mchip is the mass of removed material.
24-Oct-23 147

of Raw Materials
• CEFm is defined as the amount of carbon
dioxide produced by a unit of material
• 𝐶𝐸𝐹𝑚 = 𝐸𝐸𝑚 × 𝐶𝐼𝑚 ×
44
12
• where EEm is the embodied energy of the
material (MJ/kg) and
• CIm is the carbon intensity of the material (kg
C/MJ).
24-Oct-23 148

of Raw Materials
• Convert the embodied energy of materials to
their standard coal equivalent.
• By using the carbon intensity of coal, CEFm of
different materials can be derived.
• CEFm = EEce × CEFce
• where, EEce is the standard coal equivalent of
the material’s embodied energy and
• CEFce the carbon emission factor of coal
(kgCO2/kg ce).
24-Oct-23 149

Carbon emission factors of
commonly-used materials
24-Oct-23 150
The standard coal calorific value is 29.27 MJ/kg
Titanium 650 22.2 54.8

Carbon Emissions Due to Chip
Removal
• Material removal rate Q, the volume of removed
material per time
• Q = 1,000 vc d f.
• Then, the mass of the removal during the cutting time
tc can be obtained:
• 𝑀𝑐ℎ𝑖𝑝 = 𝑄 × 𝑡𝑐 ×
𝜌
106
= 𝑣𝑐 𝑑 𝑓 𝑄 × 𝑡𝑐 ×
𝜌
1000
ρ is the material density (g/cm3).
24-Oct-23 151

Removal
• Chips produced in the machining process are
eventually collected at an electric furnace for
metal recycling.
• The carbon emissions caused by the generation
of electricity necessary to support the recycling
process should be included as part of the
carbon emissions of the CNC machining
system.
24-Oct-23 152

Removal
• CEchip = CEFchip × Mchip
• where CEFchip is the carbon emission factor of
chips.
• Depending on the type of scraps, different
energy consumption and carbon emissions
from the recycling process.
24-Oct-23 153

Removal
• Thus the determination of CEFchip is through
its standard coal equivalent
• CEFchip = CEFce × ECce
• where ECce is the amount of standard coal
consumed in the recycling process of a unit
mass of scrap.
24-Oct-23 154

Carbon emission factor
of chips recycling
24-Oct-23 155
Titanium scrap 1.902 4.7

The composition of carbon emissions with
different spindle speed
24-Oct-23 156

The carbon emissions of different
machining methods
24-Oct-23 157

Conclusions
• Cutting fluids popularly used in machining to
improve the performance, but maintenance
and disposal of traditional cutting fluid is a
serious problem
• MQL is a potential solution for problems with
cutting fluids
• Paradigm shift towards replacement of
mineral oils with vegetable oils in cutting
fluids
24-Oct-23 158

Conclusions
• Applicability of vegetable oils in MQL well
demonstrated
• Work may be carried out on formulation and
application of different vegetable based
cutting fluids.
October 24, 2023 159

Conclusions
• Solid lubricant coatings on carbide tools
showed substantial improvement in
machining performance without the need for
the use of cutting fluids.
• Micro textures on cutting tool surfaces have
provided promising results.
• This opens the scope for studies on vegetable
based Nano-fluids in MQL, with the ultimate
goal of reaching environmental sustainability.
24-Oct-23 160

Conclusions
• Research directions
– Formulate vegetable cutting fluids to reduce the
oxidation in storage
– Performance of MQL with vegetable based cutting
fluids
– Performance of MQL with vegetable based solid
lubricant particles
– Performance of MQL with vegetable based nano-
fluids
– Solid lubricant coatings with compressed air
24-Oct-23 161

Research directions
In minimum quantity lubrication (MQL) assisted
techniques, some researchers rather favor the
concept of minimum quantity cooling (MQC).
The role of cooling with respect to the
lubrication must be explored more.
24-Oct-23 162

Research directions
• In MQL both lubrication capacity and
penetration ability of cutting fluid affect the
machining performance.
• The information of thermo-fluid properties of
cutting fluid is not reported in most of the
metal cutting related literature.
24-Oct-23 163

Research directions
• As MQL has a mixture of oil and air, CFD
modelling was introduced by the researchers.
• The CFD modelling provides flexibility to deal
with multiphase models, different flow rates
and incorporating different coolant properties
easily.
24-Oct-23 164

Research directions
• Nanoparticles can significantly improve the
heat transfer related thermal properties and
tribological performance during the metal
cutting operation.
• There is a need to explore the potential of
nano-enhanced cutting fluids for the
machining of high-performance titanium
alloys.
24-Oct-23 165

Research directions
• To prepare nano-enhanced cutting fluid,
several researchers have used single
nanoparticle type to prepare the cutting fluid.
• However, there is a need to explore the
potential of hybrid nanofluids in machining
operations.
24-Oct-23 166

Questions or Comments ?
October 24, 2023 167

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