Progress in Minimum Quantity Lubrication

Prof. YUAN Songmei Tel:86-10-82339630

Mobile:86-13681038158 Email:yuansm@buaa.edu.cn

Beihang University School of Mechanical Engineering & Automation

2014.10.23

A central location– Main campus located in Zhong

Guan Cun Science and Tech Park,

Haidian District in Beijing

– At the heart of higher learning and

science and technology

development

New Campus: 100 hectares, inShahe, Changping District

BEIHANG UNIVERSITY – QUICK FACTS

History

– Founded in 1952

Beijing Institute of Aeronautics (BIA)

- First aerospace university in China

- One of the first 16 key universities in China

– 1988

Beijing University of Aeronautics

and Astronautics (BUAA)

– 2002

Beihang University (BUAA)

BEIHANG UNIVERSITY – QUICK FACTS

27 Schools

Enrollment: 27,811

- Undergraduate Students: 14,428

- Master Students: 8,700

- Ph.D Students: 4,015

- International Students: 1,242

2,102 Faculty Members

- Full Professors: 514

- Associate Professors: 805

Over 150,000 Alumni

BEIHANG UNIVERSITY – QUICK FACTS

Full Prof., 37

Asso. Prof., 55

Assis. Prof., 57

PDRF +Technician

46

Faculty and Staff Members

Faculty: 149 Staff: 46

Introduction of SMEA(School of Mechanical Engineering and Automation)

Students

Enrolled Students: about 2000 (2013)

Most of our undergraduate students occupied the top 0.3% in National Higher Education Entrance Examination.

827

754

352

98

0

100

200

300

400

500

600

700

800

900

Undergraduate Master Ph.D. International students

Departments

Robotics Institute

Department of Industrial and Manufacturing

Systems Engineering

Dept. of Industrial Design

Dept. of Mechanical Design & Automation

Dept.of Mechatronics Engineering &

Automation

Dept. of Mechanical Manufact. & Automation

Dept. of Aircraft Manufacturing Engineering

Dept. of Material Processing & Control

Engineering

SMEA

Research Areas

No. 1

Optimum

Design Mechanical

Manufactur

ing

NDT & E

Aircraft

Manufacturing

Aircraft

Assembling

Measurement

Technology

Welding

Technics

Robotics

Quality

Management

No. 2 No. 3

No.5 No. 4 No. 6

No. 8 No. 7 No. 9

Research Incomes 160 Million RMB (about 26

million US $, 2013)

- 60 % National research projects (NSF, 863 plan, ...)

- 40% Industrial applied research funding (commercial

contracts)

Founding

Outline

Introduction 1

Key technologies 2

Progress of MQL in Beihang University 3

Cutting experiments of several materials 4

5 Conclusion

…….

The use of flood cutting fluid causes environmental pollution, health hazards,increased costs and other issues;

International Organization for Standardization Issued the ISO 14000series related to environmental management;

Manufacturing enterprises must explore a new cooling lubrication method tocreate a safe, clean production environment.

The background

Green Manufacturing

Cleaner Production

Machining Costs

Source: Huller Hille

Breakdown of Coolant Costs

Green Manufacturing

Dry Machining

today

Dry Machining

No pollution; The chips are clean and

can be recycled easily; No cutting fluid is

needed and the related cost is reduced.

切削热

In the absence of cooling, the dimensional accuracy of the workpiece is difficult to control ;

The dust is also difficult to control during the cutting process;

The application of dry machining is

limited.

formerly

Near Dry Machining

Near Dry Machining

Conventional Flooding

Dry Machining

Minimum Quantity Lubrication

Cryogenic Machining

Minimum Quantity Lubrication

with Cooling Air

Water Vapor as Coolant and

Lubricant in Green Machining

…

Minimum Quantity Lubrication with Cooling Air

Cooling air + MQL

Amount of lubricant supply is measured by ml/h，while The

amount of traditional wet method is measured by L/min.

The lubricants are environmentally friendly.

Liquid supply system is simple, small and easy layout.

Combine the advantages of the two technologies.

Reduce friction, inhibit temperature rise, prevent adhesion,

extend tool life, improve surface quality.

Feature：

Recycling of waste

Coolant storage tank of 500,000 gallons

Centrifugal filter

Pressure pump

Chemical additives

Disposal

Oil mist collector Residual oil mist

A coolant circulation system

After using MQL

Infrastructure greatly simplified

Oil mist collector Residual oil mist

Recycling of waste

Coolant storage tank of 500,000 gallons

Centrifugal filter

Pressure pump

Chemical additives

Disposal

× × ×

×

×

×

Oil generator

Chip exclusion system

Outline

Introduction 1

Key technologies 2

Progress of MQL in Beihang University 3

Cutting experiments of several materials 4

5 Conclusion

Key Technologies of MQL

System

Cutting Mechanism

Cutting Process

Oil Mist Characteristics

MQL Lubricants

MQL was first proposed by Klocke F in 1997

MQL System

MQL System

Micro-pump

Negative pressure

Pressure Separation

MQL System

External MQL

Internal MQL

•While processing groove, the interference between the

nozzle and the tool or workpiece is dissatisfied ；

•Small mist particles generated by external lubrication

can scatter, so a protective equipment is needed；

•The spindle and the tool system configuration become

complicated, hollow structures may affect the

performance of the machine tool；

• The generated mist particle diameter must be small

enough to remain suspended.

MQL Processing Technology

Turning

Dhar N R, 2006； Itoigawa F, 2006; Khan M M A, 2009； Leppert T, 2012; ...

Milling

Rahman M, 2002; S M Yuan, 2008; Kasim M S, 2013; ...

Drilling

Heinemann R, 2006; Tasdelen B, 2008; Bhowmick S, 2011; Murthy K S, 2012; ...

Grinding

Dasilva L R, 2007; Tawakoli T, 2010; Li Changhe, 2013; ...

Materials Steel: AISI4340, AISI 9310, AISI316L… Aluminum alloy: AlSi5, 7075… Titanium alloy: Ti-6Al-4V nickel-base super alloy: Inconel 718... cast magnesium alloy: AM60, AZ91 CFRP

Performance Better cooling and lubrication performance compared to dry and

flood machining; Reducing the cutting force & temperature; Improving tool life and better surface finish

Oil Mist Characteristics

Oil Mist Characteristics

Particle Size

Particle Velocity

Particle Volume

Flow Rate

Nozzle Distance

Air Pressure

Kyung-Hee Park, 2010.

Park K H, 2010; Duchosal A, 2013.

Internal Channel

Geometries

Air Pressure

Mist Settings

Oil Type

Internal Channel

Geometries

The higher nozzle pressure provided the more droplets but the smaller droplets were obtained while a smaller amount of droplets was deposited on the surface when the nozzle distance was increased.

Oil Mist Characteristics

Duchosal A, 2013.

Oil Mist Characteristics

Particle Size

Particle Velocity

Particle Volume

Flow Rate

Nozzle Distance

Air Pressure

Internal Channel

Geometries

Air Pressure

Mist Settings

Oil Type

Internal Channel

Geometries

Park K H, 2010; Duchosal A, 2013.

Oil Mist Characteristics

Duchosal A, 2013.

Oil Mist Characteristics

Particle Size

Particle Velocity

Particle Volume

Flow Rate

Nozzle Distance

Air Pressure

Internal Channel

Geometries

Air Pressure

Oil Type

Internal Channel

Geometries

Park K H, 2010; Duchosal A, 2013.

MQL Lubricants

Palm oil (MQLPO) produced lower cutting force and workpiece temperature than synthetic ester (MQLSE), almost equal to the flood condition when high speed drilling Ti-6Al-4V.

Rahim E A, 2011

Mineral oil, vegetable oil, synthetic ester

Lubricants with longer linear carbon chain can provide higher lubrication ability.

Rahim E A, 2011 Wakabayashi T, 2012

MQL Lubricants

Tai B L, 2011

Mineral oil, vegetable oil, synthetic ester

low fluid viscosity, high mist concentration, large mist droplet diameter and high wettability were best correlated with good machinability.

Fluid with low viscosity

high wettability (low contact angle)

high mist concentration

large mist diameter

relative lower thermal conductivity

large mist diameters

& high mist

concentration

improve surface finish & diameter accuracy

lower the energy consumption

Without corresponding cooling system, MQL has some disadvantages under specific cutting conditions:

Lack of cooling performance, especially when dealing with high cutting

temperature caused by difficult-to-cut materials.

Lubrication performance may be insufficient.

Lubricant film breakage under high cutting temperature, Lubrication

failure.

…

New strategies have to be taken to enhance the cooling & lubricating performance of MQL.

Minimum Quantity Lubrication with Cooling Air (MQL-CA)

Minimum Quantity Lubrication with Cooling Air, MQL-CA

Prof. He Ning from Nanhang University uses the low temperature liquid nitrogen mixed with oil mist to cut titanium alloy TC4. The result suggests that MQL-CA has a better effect in Inhibition of tool wear compared with Liquid nitrogen cutting.

Nguyen T’s research shows that, for low metal removal machining process, the cooling air can reduce surface erosion and cutting force. As for higher metal removal rate, adding vegetable oil mist in the cooling air can effectively improve the processing state.

[Su Y, 2006.]

[Nguyen T, 2003.]

Spanish scholars Sanchez JA et al research the performance of grinding AISI D2 tool steel by combining MQL with low temperature CO2 system. This experiment shows that the consumption of the lubricant was decreased during the grinding process, while protecting the abrasive wheel. Therefore, both the grinding wheel life and surface quality are improved.

[Sanchez J A, 2010.]

MQL Cooling Air

MQL Liquid Nitrogen

MQL Cryogenic CO2

Outline

Introduction 1

Key technologies 2

Progress of MQL in Beihang University 3

Cutting experiments of several materials 4

5 Conclusion

• In 2005, our research group engaged in MQL cutting technology and system;

• In 2006, got the funding of National Sci-tech Support Plan—Research on the green cutting process in the machinery

manufacturing;

• 2006.07.19, applied the first national invention patent in minimum quantity lubrication;

• 2008.03.17, applied the second national invention patent in minimum quantity lubrication;

• 2008.03, performed cutting experiments on cast iron and high strength steel in MQL condition;

• 2008.06.18, applied the third national invention patent in minimum quantity lubrication;

• 2008.08.26, applied the fourth national invention patent in minimum quantity lubrication;

• 2009.07.16, applied the PCT patent—a minimum quantity lubrication system

• In 2007, our research group engaged in MQL with cooling air cutting technology and system;

• 2008.11, developed the prototype of the cooling air system one;

• 2008.12, performed cutting experiments on titanium alloy in MQL with cooling air condition;

• 2009.01, developed the prototype of the cooling air system 2 and 3;

• 2009.06, applications of MQL and cooling air systems in aerospace companies;

• 2010.03, applied the national invention patent in MQL with cooling air system;

• 2012.01, got the funding of National Sci-tech Support Plan—Mechanism and device of MQL with cooling air cutting

technology.

• … ….

Research and development process of BUAA in MQL-CA

The development of MQL-CA systems

The MQL systems

Technical indicators

Air pressure: 0.4-0.8Mpa

Oil: MQL oil

Flow rate: 0～50ml/h

Pressure: Adjustable

Installation

The cavity is suspended on the machine bed

cooling pipe is fixed with a magnet

Cryogenic systems

Cooling Air System-Ⅰ

空气压

缩机

干燥过滤

器

蒸发器

制冷压缩

机

油水分离器

冷凝器

储液器

电磁阀

冷空气

膨胀阀

干燥过

滤器

Cooling Air System-Ⅱ

-60

-50

-40

-30

-20

-10

0

10

20

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

时间 /min

气流温度

/℃

双级制冷

单级制冷

Air flow rate: v=0.2～0.7m3/min； Temperature difference between the outlet and the inlet: △t=0～-40℃ Temperature fluctuations: △T≤±1.5℃

www.exair.com

National invention patent certificates

Outline

Introduction 1

Key technologies 2

Progress of MQL in Beihang University 3

Cutting experiments of several materials 4

5 Conclusion

压缩空气

低温

系统

Ⅰ型

MQL

系统

冷风

油/气

主轴

刀具

z

x

y

工件

电荷放大器

电脑

测力仪

The cutting experiment of superalloy GH4169

The experimental condition Machining

tool DMU 80T CNC Machining Center

Material GH4169(Inconel 718）

Tool Sandvik, two teeth

Blade Sandvik, 1030, 1030R08

Cutting speed 31.4m/min

Cutting depth 0.5mm, 0.75mm, 1.0mm, 5.0mm

Cutting width 20mm, 4.0mm

Feed per tooth 0.025mm/z, 0.075mm/z

MQL

parameters

Lubricant flow rate:12mL/h;

Compressed air flow rate: 88L/min

Cooling air

parameters

Lubricant flow rate: -5℃;

Compressed air flow rate: 280L/min

Wet cutting Emulsion（water based）

Cooling

method Flood cutting fluid, MQL-CA

30

32

34

36

38

40

42

44

46

48

-60 -40 -20 0 20 40 60

测试点距离工件中心的位置 /mm

已加工表面硬度

HR

C

传统浇注式切削

MQL-CA

The comparison of machined surface hardness values

The cutting experiment of superalloy GH4169

The comparison of surface roughness The comparison of tool wear

The cutting experiment of titanium alloy TC4

150

170

190

210

230

250

270

290

310

330

1 3 5 7 9 11 13 15 17 19 21 23 25

铣削时间 /min

铣削力

/N

MQL-CA 干切削

冷风 传统浇注式

MQL

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

1 2 3 4 5 6 7 8 9 10 11 12 13

铣削时间 /min

刀具后刀面磨损量

/m

m

传统浇注式 干切削

冷风切削 MQL-CA

MQL

Machining tool XK7132 CNC Milling Machining Center

Material TC4 (Ti-6Al-4V) alloy, 120×100×30mm

Tool Stellram,7792 VXD09

Blade Stellram, XDLT-D41

Cutting speed 126m/min

Cutting depth 0.25mm

Cutting width 32mm

Feed per tooth 0.25mm/rev

MQL

parameters

Lubricant flow rate: 80ml/h; Compressed air flow rate: 88L/min

Cooling air

parameters

The temperature of cooling air：-25℃; The flow rate of cooling air：280L/min

Cooling method Dry machining, flood cutting, cooling air

machining, MQL, MQL-CA

The change of cutting force while milling titanium alloy The process of tool wear while milling titanium alloy

The minimum cutting force is obtained during the MQL-CA cutting progress which has relatively better lubrication and cooling effect.

The tool wear is significantly controlled by using MQL-CA technology, which results in longer tool life.

During the progress of dry cutting, cooling cutting, and flood cutting, metal bonding is obviously observed on the tool tip.

During the MQL and MQL-CA cutting progress, no metal bonding is

observed on the tool tip.

The cutting experiment of titanium alloy TC4

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

后刀

面磨

损V

Bm

ax（mm）

切削时间（min）

干切削

传统切削

冷风切削

低温微量

润滑切削

干切削

传统切削

冷风切削

低温微量润滑切削

The cutting experiment of high-strength steel 30CrNi2MoVA

Machining tool VMC0850B Machine Center

Material 30CrNi2MoVA

Tool cemented carbide φ40mm, two teeth

Spindle speed 2000rpm

Back engagement 0.5mm

Cutting width 40mm (slot milling)

Feed per tooth 0.05mm/z

The flow rate

of lubricant 10~20ml/h

Cooling air

parameters -30℃; 500L/min

Cooling

method

Dry machining, flood cutting, cooling

air machining(-30℃), MQL-CA

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

1.5 3 4.5 6 7.5 9 10.5 12 13.5 15 16.5

表面

粗糙

度Ra(μm)

切削时间（min）

干切削

传统切削

冷风切削

低温微量

润滑切削

干切削 低温微量润滑切削

干切削 传统切削 冷风切削低温微量滑

切削

颜色

形状

400

450

500

550

600

650

700

750

1.5 3 4.5 6 7.5 9 10.5 12 13.5 15 16.5

切削

力（

N）

切削时间（min）

干切削

传统切削

冷风切削

低温微量

润滑切削

The cutting experiment of high-strength steel 30CrNi2MoVA

The machined surface under the microscope (Magnification 180)

Outline

Introduction 1

Key technologies 2

Progress of MQL in Beihang University 3

Cutting experiments of several materials 4

5 Conclusion

Conclusion

Manufacturing sustainability can be achieved by Minimum Quantity Lubrication with Cooling Air (MQL-CA) cutting technology.

MQL-CA uses very tiny amount of lubricant to maintain or surpass the cutting performance using traditional way.

It requires future efforts to face the scientific and technical challenges: Profound research on the cutting mechanism of MQL-CA is

required to provide scientific guidance for engineering application.

New MQL-CA system for machine tools with special structure, such as: multi-axis and turning-milling machine centers.

Eco-friendly and bio-degradable MQL/MQL-CA Lubricant Protection against oil mist, clean and safe work space Develop cutting parameter database for MQL-CA

Thank you for your attention！

Prof. YUAN Songmei

School of Mechanical Engineering and Automation

BEIHANG UNIVERSITY,BEIJING,P.R.CHINA

Tel:86-10-82339630

Mobile:86-13681038158

Email:yuansm@buaa.edu.cn