Advertisement

Relationship of Oil Composition and Lubricating Characteristics in Cold Rolling Aluminum Strips

  • Yongtao Zhao
  • Jianlin Sun
  • Guangzhao Yuan
  • Chenglong Wang
Conference paper
Part of the Lecture Notes in Mechanical Engineering book series (LNME)

Abstract

To explore the relationship of oil composition and lubricating characteristics, new base oils with different carbon chain length and aromatics contents for lubrication in cold rolling aluminum process were investigated by means of Gas Chromatography-Mass Spectrometry. Tribological tests were carried out on a four-ball friction and wear testing machine. Results showed that the film strength gradually increased with an increasing of aromatics content in oils and friction coefficients decreases simultaneously. Cold rolling experiments were conducted to be further to analyze the lubrication effects of new rolling oils by a 4-high mill. The curves of lubricating characteristics in rolling were obtained, and the minimum rolling thickness after rolling under different lubricating conditions was found to decrease obviously.

Keywords

Rolling oil Composition Lubrication characteristics 

Introduction

High-speed rolling of aluminum strips has made great progress. Rolling speed of aluminum strips is assorting from 30–100 m/min to more than 600–1000 m/min. Rolling velocity of high-speed rolling is assorting from 600–1100 m/min to 1500 m/min or more. Ultra-high speed rolling mills with rolling velocity of more than 2500 m/min have been used currently [1, 2, 3]. In the high-speed rolling, it only takes even dozens of milliseconds for the rolled pieces go through the rolling area. In such a short time, it’s kept up high speed and produced great deformation heat and friction heat in rolling deformation zone. Friction heat and deformation heat of base oils is obvious in non-Newtonian laminar flow, which can’t be ignored. The lubrication state in aluminum strips rolling will have a great influence on rolling process. Moreover, oil composition and lubricating characteristics determines the lubrication state in aluminum strips rolling.

Traditional oiliness additives, including some organic acids, alcohols, lipids, etc. [4, 5], can’t satisfy the practical condition of high speed, wide rolling and big pressure rate because of comparative low film strength. Traditional aluminum rolling oils by adding additives can’t meet the demands of increasingly stringent lubricating conditions [6, 7, 8]. Thus, in order to meet the modern rolling production requirement of higher the extreme-pressure properties, the effects of rolling oils with different carbon chain length and aromatics content on the lubricating characteristics, for example, friction coefficients and the minimum rolling thickness, are deeply studied.

Experimental

New base oil N100 and N80 for aluminum rolling strips and foils with different aromatic contents were explored. Aromatic contents of base oils are shown in Table 1. A gas chromatography-mass spectroscopy experiment was performed to explore the length of carbon chain of the oils, according to the standard of ASTM D2425-04.
Table 1

Aromatic contents of two type base oils (mass percent)

Base oils

Aromatic contents (mass percent)

N100

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

N80

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

MR-S10A four-ball friction and wear testing machine was used to test maximum non-seized load PB of two type base oils with different contents of aromatics. According to the standard of ASTM D2783-03, four bearing steel balls with a diameter 12.7 mm are made by GCr15 and their hardness is 64–66 HRC. In this technique, one steel ball under load is rotated against three stationary steel balls, these three stationary balls held in the form of a cradle. All balls are immersed in the lubricant. The PB value tests are conducted at a rotary speed of 1760 rpm and ambient temperature of about 25 °C. And the wear tests are conducted at a rotary speed of 1200 rpm for 30 min while the load is 392 N. When test is finished, the wear scar diameter of the steel balls was observed by means of the optical microscope.

Cold rolling experiments of aluminum foils were carried out on a Ф95/Ф200 × 200 mm four high mills. The technical parameters of the mill are given in Table 2. The minimum rolling thickness of the aluminum strips were measured by means of 4-high mill.
Table 2

Technical parameters of four roller reversible rolling mill

Items

Working roll diameter (mm)

Roller width (mm)

Support roll diameter (mm)

Main motor power (kw)

Roller rotary (m s−1)

Motor speed (n min−1)

Parameters

95

200

200

35

60

30–300

Results and Discussion

The compositions of base oils N100 and N80 are analyzed by gas chromatography-mass spectrometry, meanwhile that are compared with the similar commercial products named D100 and D80, shown in Table 3. The figures in Table 3 indicate carbon chain of N100 base oil distributed in the range of C13–C18, whereas N80 base oil distributed in the range between C12 and C16.
Table 3

Distribution of carbon chain in N100 and N80 base oils with D100 and D80

Base oils

C10

C11

C12

C13

C14

C15

C16

C17

C18

N100

10.46

43.79

43.03

2.340

0.1

0.28

D100

3.2

28.6

41.1

26.1

0.8

N80

12.73

53.33

33.56

0.38

0.38

D80

0.1

8.8

35.7

47.0

8.4

The distributions of carbon chain in base oils have a fundamental influence on the lubricating behavior of lubricant, as it plays a crucial role in determining the viscosity of lubricated oil. A long carbon chain length always represents high viscosity of oil while short carbon chain length means that a low viscosity of oil is present.

It is shown in Table 3 that the carbon chain of N100 is mainly concentrated in C14–C15 components, which are more than 85% of the total in mass, while carbon chains of the general oil samples are mainly concentrated on C11–C13. Although commercial oil’s Carbon chain distribution is concentrated, but the carbon chains are shorter than those of N100 in general, resulting in the base oils of low viscosity, low film strength, and not beneficial to improve the quality of rolled surface during production. The carbon chain of N80 is mainly concentrated in C12–C14, which is more than 85% of the total in mass, especially the mass of C15–C16 components which is only less than 1% of the total. The rest of C12 component is the light component. Comparing with D80, N80 base oil contains a better carbon chain distribution structure, resulting in the characteristics of wide distillation range, high viscosity, more suitable for modern aluminum foil production. These new type base oils with narrow carbon chain distribution and narrow distillation range are closer to practical production process requirements.

The tribological experiments were carried out to measure film strength, the wear scar diameter and friction coefficients of base oils with different aromatics contents. In the base oil, film strength is changing with the aromatics content. The results are shown in Fig. 1.
Fig. 1

Film strength of base oils of N80 and N100 base oil

When the aromatics content of N100 base oil is 0.1–0.5%, film strength attain to 98 N. When the aromatics content is more than 0.5%, film strength is increasing rapidly. When the aromatics content is more than 0.7%, film strength almost remained constant, Value is 108 N.

However, as for N80 base oil, the aromatics content is 0.1%, film strength is 98 N. The aromatics content is continually increased to 0.3–0.7%, film strength is 108 N. The aromatics content further reaches 0.8–1.0%, film strength increases with the increase of aromatics contents, when the aromatics content increased to 1.0%, film strength reach up to 118 N.

The results indicate that film strength of two type base oil increases simultaneously with the increasing of aromatics content. With lower viscosity, film strength is sensitive to aromatics content. The N80 base oil increases simultaneously with the increasing of aromatics content, which is more obvious than N100 base oil.

Average friction coefficients and the wear scar diameter of N100 and N80 base oils depend on the content of aromatics in them. Figures 2 and 3 represent the Average friction coefficients and the wear scar diameter of different concentration of aromatics in N100 and N80, respectively. It is seen that average friction coefficients and the wear scar diameter of the base oil decreases with the increase of aromatics, indicating that the addition of aromatics would help to improving the lubrication performance in a large extent. An interesting phenomenon is also found in these two figures. It seems that aromatics in the N80 would cause more outstanding influence on the lubrication performance compared to aromatics in the N100. Possibly due to lubrication characteristics of lubricant is more sensitive to the content of aromatics when the lubricant is in a low viscosity.
Fig. 2

Average friction coefficient of the N80 base oil

Fig. 3

Average friction coefficient of the N80 base oil

Cold rolling experiments were performed on a 4-high mill under different lubricating conditions, and the minimum rolling thickness of the aluminum strips were recorded and shown in Figs. 4 and 5.
Fig. 4

Minimum rolling thickness of N80 base oil

Fig. 5

Minimum rolling thickness of N100 base oil

Under the lubricating condition, smaller minimum rolling thicknesses of the aluminum strips are obtained compared to that without lubricant. For the base oil containing aromatics, boundary lubricating film, which is composed by chemisorbed film and tribochemical film between the aluminum strips and the roller surface, can be formed in the rolling process. Data of cold rolling experiments indicate aromatics in oils have a significant influence on lubricating characteristics. As the friction coefficients and the minimum rolling thicknesses are evidently reduced by adding aromatics to base oil.

Another phenomenon is also found in these two figures. The minimum rolling thickness of aluminum strips decrease with the increasing of aromatic content in oils. The minimum rolling thickness of N100 base oil is 0.021 mm in the non-lubrication condition. Under lubrication of N100 base oil with 1% aromatic content, the minimum rolling thickness is 0.014 mm, which reduced 33.3% compared with the sample rolled under non-lubricated condition. Under lubrication of N80 base oil with 1% aromatic content, the minimum rolling thickness is 0.015 mm, which reduced 28.6% compared with the sample rolled under without lubricated condition.

With the increase of aromatics content, film strength can be increase, friction coefficient can be decreased and the minimum rolling thickness can be reduced. Not only it meets the requirements of environmental protection, but also ensures the lubricating performance.

Summary

  1. (1)

    With increasing content of aromatics, the film strength increases. When the viscosity is lower, the sensitivity of the aromatics content on the film strength is higher, which demonstrates that with the increasing of aromatics content, the complement ability of rolling base oil to the extreme-pressure properties is gradually improved, the anti-friction property of the oil is also improved.

     
  2. (2)

    Average friction coefficients and the wear scar diameter of the base oil decreases with the increasing of the content of aromatics, indicating that the addition of aromatics helps to improve the lubrication performance in a large extent.

     
  3. (3)

    Rolling experiment results show that with the enhancement of aromatic content in rolling oils, the minimum rolling thicknesses of the aluminum strips obviously reduces, which can satisfy the demand of modern aluminum strips rolling with high speed.

     

References

  1. 1.
    X. Fu, W. Yao, L. Zhang, The current status and development trend of additives in lubricating oils. Automobile Technol. Mater. 5, 1–6 (2005)Google Scholar
  2. 2.
    W. Du, G. Li, Oil residual on foil surface with wider width high speed aluminum foil mill and improving methods. Light Alloy Process. Technol. 35(6), 34–35 (2007)Google Scholar
  3. 3.
    C.N. Panagopoulos, E.P. Georgiou, Cold rolling and lubricated wear of 5083 aluminum alloy. Mater. Des. 31, 1050–1055 (2010)CrossRefGoogle Scholar
  4. 4.
    J. Sun, Y. Sun, M.A. Yanli et al., Effect of rolling oil on the surface quality of annealed aluminum foils. J. Univ. Sci. Technol. B 30(2), 137–140 (2008)Google Scholar
  5. 5.
    J. Shibata, T. Wakabayashi, S. Mori, Adsorption characteristics and lubricating performance of coolant components in cold rolling of aluminum. Tribol. Int. 40(5), 748–753 (2007)CrossRefGoogle Scholar
  6. 6.
    J. Sun, Y. Kang, T. Xiao, J. Wang, Lubrication in strip cold rolling process. J. Univ. Sci. Technol. B 11(4), 368–372 (2004)Google Scholar
  7. 7.
    J. Sun, Y. Huang, M. Lu, Optimize aluminum’s surface roughness in rolling lubrication process. Ind. Lubr. Tribol. 65(3), 175–180 (2013)CrossRefGoogle Scholar
  8. 8.
    Z. Liao, S. Yang, Analysis and discussion on effect factors of aluminum foil rolling process. Nonferrous Met. Process. 43(1), 21–24 (2014)Google Scholar

Copyright information

© Springer Nature Singapore Pte Ltd. 2018

Authors and Affiliations

  • Yongtao Zhao
    • 1
    • 2
  • Jianlin Sun
    • 1
  • Guangzhao Yuan
    • 1
  • Chenglong Wang
    • 1
  1. 1.School of Materials Science and EngineeringUniversity of Science and Technology BeijingBeijingChina
  2. 2.School of Mechanical EngineeringHenan University of EngineeringZhengzhouChina

Personalised recommendations