1. Wear behavior of steel wire under grease lubrication
Beom-Taek Jang
Graduate school of Mechanical Engineering, Kyungpook National University
Supervised by Prof. Seock-Sam Kim
I am glad to see all of you, thanks professor kim and professor umehara for giving me a chance to introduce my study.
The title of my study is “wear behavior of steel wires under grease-lubricated slipping wear test
I am going to tell you in the order of research background, purpose and experimental results.

2. Contents Introduction Back ground, Purpose of this study
Experimental Details
Experimental results
Friction coefficient, Wear amount
Discussion
Wear mechanism, Wear coefficient
Conclusions
Steel wire ropes are critical load-bearing components in a wide range of applications such as cranes, lifts, mine haulage, etc.
A wire rope is a complex component usually consisting of six or more strands in helical form around a core made of fibre
this figure shows an elevator system
Let me explain briefly to understand physical phenomenon easier.
The traction machine installed On top of the building carries the passanger’s car up and down
During sevice a wire rope contiuously deteriorates(wear out) under several influences which include tension, bending, fatigue, corrosion and wear.
Among these influences, I’m focusing on the external wear of outside rope wires resulting from it’s slipping on the sheave
As you see, the figure taken from the field shows a lot of wear particles attached on the surface of rope wires.
so I guess that the wear paticles affect the external wear of outside rope wires not escaped by the viscosity of grease lubricant.

3. Background-problems Steel wire ropes What’s problem?
are critical load-bearing components in a wide range of applications such as cranes, lifts, mine haulage, etc.
Steel wire ropes are critical load-bearing components in a wide range of applications such as cranes, lifts, mine haulage, etc.
A wire rope is a complex component usually consisting of six or more strands in helical form around a core made of fibre
this figure shows an elevator system
Let me explain briefly to understand physical phenomenon easier.
The traction machine installed On top of the building carries the passanger’s car up and down
During sevice a wire rope contiuously deteriorates(wear out) under several influences which include tension, bending, fatigue, corrosion and wear.
Among these influences, I’m focusing on the external wear of outside rope wires resulting from it’s slipping on the sheave
As you see, the figure taken from the field shows a lot of wear particles attached on the surface of rope wires.
so I guess that the wear paticles affect the external wear of outside rope wires not escaped by the viscosity of grease lubricant.
What’s problem?
Micro-slip production between wire rope and sheave grove during the reciprocating as shown in Fig.1
Grease lubricants Interact with wear particles.
Friction coefficient varies due to changing of lubrication condition

4. Background-Rope slip T2 T1
The relative motion of the rope in a sheave groove has two components and is given by the superposition of both
1.The rope stretch (elongation) is proportional to the tension and varies accordingly, while there is practically no tangential deformation of a steel or cast-iron sheave. Since there is a considerable difference between the tensile forces on the tight and slack sides of the sheave, a change in tension occurs in each individual portion of the rope whilst passing around the sheave , resulting in a slippage.
2. Rope slip caused by other ropes the speed of which is different because of different pitch diameters of the sheave grooves. This factor is of considerably greater influence.
From ‘ELEVATOR MECHANICAL DESIGN’ written by LUBOMIR JANOVSKY T2 T1
The rope stretch (elongation) is proportional to the tension and varies accordingly, while there is practically no tangential deformation of a steel or cast-iron sheave. Since there is a considerable difference between the tensile forces on the tight and slack sides of the sheave, a change in tension occurs in each individual portion of the rope whilst passing around the sheave , resulting in a slippage
Fig. 1 Distribution of contact pressure between rope and sheave in traction machine of elevator system

5. Background-operating condition
During the initial wearing-in an incomplete protective transfer film developed in the crevices and irregularities on the wire surface.
From ‘Environmental and sheave material effects on the wear of roping wire and sheave’
by M. G. Hamblin and G. W. Stachowiak, Tribology International Volume 28 (1995) FN
V1steel wires
Grease
condition
Mixture
With particle
Pure dry
condition
Changing of values
V2: sheave
와이어 로프의 심강에 축적된 그리스가 시간이 지남에 따라 없어 지게 되며 결국 무윤활에서 rolling/sliding 운동을 하게 된다.
On the contact surface between hard steel (wire) and mild steel (sheave)
The lubrication condition is involved in the region of boundary lubrication
The thickness of grease film ranges from 10-3 to 10-2μm
The roughness of two materials ranges from 1 to 25μm

6. Purpose of this research
Rolling/sliding wear tests for various speed and slip ratios under dry and grease conditions
Measurement variation of Friction coefficient in each case
Quantification of wear amount under dry and grease lubrication
Observation on the worn surface by using FE-SEM
The purpose of this study is to observe the effect that the wear particles interact with grease lubricant
we carried out the wear tests, and the friction coefficient is recorded by computer.
After testing in each case, the wear particles will be collected from specimen using a clean syringe[səríndʒ] near the contact area.
The surface of the wear components will be analyzed by using particle analyzer.
Finally I will discuss the characteristics of the wear particles and their changes.
Derivation of wear coefficient from this study in various rolling speed and use it for maintenance/repair

7. Experimental procedure
Measurement of surface roughness
Ultrasonic Cleaning & Dry
Rolling wear test
Measurement of wear amount
SEM
Simulative wear testing of hard drawn steel wire against Nodlar cast iron applied in real system will be attempted by Rolling contact wear tester
Chemical component for the test materials are provided in above table.
In the test, test materials are combined with different revolutions respectively to produce relative slipping.
Grease lubricant is brushed onto the contact surface of the upper disk.
In the test, the wear behavior of HSWR(hard drawn steel wire) in the presence of grease is characterized side-by-side with unlubrication

8. Experimental apparatus
Rolling Contact Wear Tester
Upper Disk [ Hv = 400 ]
- Material: High carbon steel wire rods (HSWR 52A)
- Chemical component: KS D 3559
Lower Disk [ Hv = 310 ]
- Material: Nodular cast iron (GCD 700)
- Chemical component: KS D 4302
R 2
Ø60 C Si Mn P S
0.59 ~
0.66
0.15 ~ 0.35
0.30 ~
0.60
~ 0.04
D 0.94
Ø60 C Si Mn P S Mg
3.2 ~
4.2
0.8 ~ 6.0
~ 1
0.4 ~
0.91
~ 0.2
~ 0.08
Simulative wear testing of hard drawn steel wire against Nodlar cast iron applied in real system will be attempted by Rolling contact wear tester
Chemical component for the test materials are provided in above table.
In the test, test materials are combined with different revolutions respectively to produce relative slipping.
Grease lubricant is brushed onto the contact surface of the upper disk.
In the test, the wear behavior of HSWR(hard drawn steel wire) in the presence of grease is characterized side-by-side with unlubrication
W 6
In the test, test material upper and lower disk are combined with revolutions of ( ) and ( ) rpm
respectively to produce relative slipping.
Grease lubricant is brushed onto the contact surface of the upper disk.

9. Experimental condition
Table.1 Experimental conditions
Rolling speed, m/s
Applied Load, N
Slip ratio, %
Temperature in chamber, ℃
Initial surface roughness Ra, μm
Steel wire
Nodular cast iron
Total number of cycles (steel wires)
Test environment
1.62, 2.27, 3.25
196
0.1, 0.5, 1
[ 25±2 ]
[ 2±0.25 ]
[ 5±1 ]
[ ]*
Dry, Grease
We performed test as shown table.1
Here, Test was stopped initially cycles and subsequently every cycles to measure wear amount and worn surface
* Test was stopped initially cycles (running-in period) and subsequently
every cycles to measure wear amount and worn surface

10. Measurement of wear scar
Measurement of wear depth (h) and width by using configuration measuring instrument (Mahrsurf XC20)
Lower specimen
We measured the maximum wear depth of steel wires which was deformed elastically
And The slip ratio was set up by using this fomular to generate
The slip ratio is calculated using as follow formula

11. Calculations of wear volume
The wear volume is calculated by using as follow formula:
We measured the maximum wear depth of steel wires which was deformed elastically
And The slip ratio was set up by using this fomular to generate

12. Experimental results-Friction coefficient
During the test, we collected the data of friction coefficient under dry and grease condition respectively.
Figure shows that the effect of s~~
In dry condition, there was no change for friction coefficient of three types of slip ratios
On the other hand, under grease condition as the running time increase it appeared the difference of friction coefficient.
It is considerd that the wear paritcles interact between two surfaces
(a)
(b)
Fig. 1 Effect of slip ratios on the friction coefficient at a rolling speed 2.27m/s and normal load 196N under (a) dry and (b) grease condition

13. Experimental results-Friction coefficient
This Figure shows the effect of the rolling speed on the friction coefficient curve for the sliding distance under the dry, grease and the standard conditions for the other parameters i.e.[ail] contact load of 196N, slip ratio of 0.5% at room temperature.
With the increasing sliding distance, the friction coefficient becomes finally steady after passing running-in period
In grease lubrication
초기에는 건조마찰과 비슷한 경향을 보이다가 어느 시점이 지나서는 각각이 마찰계수의 차이를 나타내었다.
이는 시간이 경과함에 따라 표면에서 발생한 마모입자의 영향으로 인해 차이를 보이는 것으로 사료된다.
The reason for the difference in the steady state friction coefficient
(a)
(b)
Fig. 2 Effect of rolling speed on the friction coefficient at a slip ratio of 0.5% and normal load 196N under (a) dry and (b) grease condition

14. Experimental results-Wear amount
Figure.3 shows the Variation of the maximum wear depth of steel wire for various rolling speed under dry-grease conditions at 196N and slip ratio of 0.5%
(a)
(b)
Fig. 3 Variation of the (a) max. wear depth and (b) wear volume of steel wire for various rolling speed under dry and grease conditions at 196N and 0.5%

15. Experimental results-Wear amount
Figure. 2 shows the variation of maximum wear depth of steel wire for various slip ratio under dry-grease conditions at 196N and 2.27m/s
Under lubrication at slip ratio of zero point 1 percentage, the maximum wear depth vvery little changed with increasing number of cycles
(a)
(b)
Fig. 4 Variation of (a) max. wear depth and (b) wear volume of steel wire for various slip ratio under dry-grease conditions at 196N and 2.27m/s

16. Experimental results-Wear rate
Figure.3 shows the Variation of the maximum wear depth of steel wire for various rolling speed under dry-grease conditions at 196N and slip ratio of 0.5%
(a)
(b)
Fig. 5 Variation of the wear rate of steel wire for (a) various rolling speed (b) various slip ratio under dry-grease conditions at load of 196N

17. Experimental results-worn surface
(b)
Fig. 6 SEM photograph showing worn surface of steel wire as a function of number of contact cycles at the normal load of 196N, rolling speed of 1.62m/s and slip ratio of 0.5% under (a)dry and (b)grease condition. The arrow indicate sliding direction.

18. Experimental results-worn surface
(b)
Fig. 7 SEM photograph showing worn surface of steel wire as a function of number of contact cycles at the normal load of 196N, rolling speed of 1.62m/s and slip ratio of 0.5% under (a)dry and (b)grease condition. The arrow indicate sliding direction.

19. Experimental results-worn surface
(b)
Fig. 8 SEM photograph showing worn surface of steel wire as a function of number of contact cycles at the normal load of 196N, rolling speed of 3.25m/s and slip ratio of 0.5% under (a)dry and (b)grease condition. The arrow indicate sliding direction.

20. Discussion-wear mechanism
Wear mechanism in rolling/sliding contact under grease condition
Adhesive &
Abrasive wear
As the number of cycles increases
Adhesive wear
Three- body
abrasive wear
fatigue wear
ploughing
asperity
substrate
crack
asperity
wear particles
asperity
substrate
9ⅹ104 cycles

21. Discussion-Wear coefficient
After running-in period in rolling/sliding motion the mechanical wear processes, especially those that depend on adhesion or abrasion, are likely to be operating simultaneously
Time or distance
Mean volume
Running-in
Steady wear
Figure. 2 shows the variation of maximum wear depth of steel wire for various slip ratio under dry-grease conditions at 196N and 2.27m/s
Under lubrication at slip ratio of zero point 1 percentage, the maximum wear depth vvery little changed with increasing number of cycles
Fig. Typical wear behavior over the life of a component. An initial period of running-in(in which the wear rate is comparatively high) is followed by a steady low-wear regime which is terminated when fatigue mechanisms come into play.

22. Discussion-Wear coefficient
Table. 2 K values of steel wire
Conditions
Wear coefficient(K)
[N]
[m/s]
Dry
196
1.62
7.60×10-5
2.27
6.78×10-5
3.25
5.84×10-5
Grease
2.35×10-5
6.66×10-5
5.16×10-5
Figure. 2 shows the variation of maximum wear depth of steel wire for various slip ratio under dry-grease conditions at 196N and 2.27m/s
Under lubrication at slip ratio of zero point 1 percentage, the maximum wear depth vvery little changed with increasing number of cycles
Fig. 9 Linear regression of wear volume of steel wire for various rolling speed under dry-grease conditions at 196N and slip ratio of 0.5%

23. Conclusions
This study focuses on the wear behavior of steel wires and effect of grease
condition against dry condition by using the rolling contact wear tester
under various slip ratio and rolling speed. The experimental results are
summarized as follows:
As the sliding distance increase, the friction coefficient curves for various slip ratios under dry condition remains unchanged. on the other hand, under grease condition it appeared the difference in the stage of steady state. In case of rolling speed increase under grease condition , the friction coefficient curves remains changed temporarily in the middle of sliding period and become similar to dry condition
During the grease tests most of steel wires suffered severely some amount of three-body abrasive wear compared to the dry tests . After the transferred debris was developed the wear of both specimens was reduced to low rates.
The wear coefficient under dry condition ranged from 5×10-5 to 8×10-5 .
on the other hand, under grease condition it was 2 to 5.5×10-5
The wear coefficient obtained in this research is important for predicting wear conditions and maintaining wire rope playing a important role in traction machine
본 논문은 아직 완성된 것이 아니다. 마모입자에 대한 추가적인 실험결과를 분석 해야한다.
This study is not complete yet, so we do need an additional analysis such as size, shape of wear particles
That’s all Thank you for your attention.