International Journal of Advanced Engineering Technology
E-ISSN 0976-3945
Research Article
EVALUATION OF EXTREME PRESSURE PROPERTIES
LUBRICATING OILS USING FOUR BALL FRICTION
TESTING MACHINE.
Dr. B.S. Kothavale
Address for Correspondence
Professor, Mechanical Department, MIT COE; Pune MS INDIA
ABSTRACT:
Load Carrying Capacity of EP lubricating oil is important parameter for their application. The viscosity shows anti wear
benefits to lubricants noticed through decrease in wear scar diameter with increasing viscosity by varying percentage of
additives. The anti wear additive studied have been found to show anti wear properties of lubricants under the experimental
condition. The test was carried out on four ball testing model under atmospheric pressure of lubricant at different loads and
at room temperature. Anti wear properties of oils like 320, 90 EP and 140 EP gear oil are evaluated. Critical Seizure Load,
Weld Load, Wear Index (mean Hertz Load) are determined in this study.
KEYWORDS: load carrying capacity, ASTM D2783-82, Four Ball EP tester.
INTRODUCTION
The four Ball wear test is used to determine the
wear preventing properties of lubricants on sliding
metal surfaces operating under boundary
lubrication conditions.
Wear is a progressive loss of a component as result
of relative movement at the surface. The contacts
subjected to wear during their long term operation
and wear failure indubitable by pitting, scuffing
and abrasion. Tribology related failures constitute
about 30 percent failure in mechanical systems and
components in plant. This problem can be
minimized by proper selection of lubricant for
particular mechanism from wear consideration. The
wear preventive properties of lubricant were
obtained by introducing anti wear additives and
evaluate through wear scar diameter or load wears
index. The Four Ball EP tester is designed to
evaluate performance under much higher unit loads
than applied on the wear test, hence designed as EP
(Extreme Pressure). One steel ball is rotated against
the other three stationary balls at constant speed,
but temperature rise is controlled. The load
is
increased at specified intervals until the rotatery
ball seizes and welds to the other balls. At the end
of each interval, the scar diameter is measured and
recorded. Two values from EP test are generally
reported, Load Wear Index (formerly called mean
Hertz load) and Weld Point. [1] Load Wear Index
(LWI) is a measure of the ability of the lubricant to
prevent wear at applied loads. Weld point is the
lowest applied load at which either the rotary ball
seizes and welds to the three statuary balls. It
indicates the point at which the extreme pressure
limit of the lubricant is exceeded. [3]. The four ball
EP test is caused in lubricant quality control and
differentiates between lubricants having low,
medium and high extreme pressure qualities.
For comparison of the capabilities of various
lubricants the result of four ball test should be
IJAET/Vol.II/ Issue III/July-September, 2011/56-58
considered, if additives are unknown or widely
dissimilar.
Here is experimental report of three oils carried out
on test rig developed Four Ball Tester using ASTM
D 2783-82 standard method and load carrying
capacity of oils are calculated.
2. EXPERIMENT
2.1 Lubricants
Three lubricants oils SAE320, SAE 90 EP, and
SAE 140 EP gear oil are evaluated on four ball
tester for load carrying capacity. Physical
properties of lubricants are appeared in Table 1
which are obtained from manufactures data.
Table1: Physical properties of Lubricants
Lubricants
140 EP
grade oil
90 EP
grade oil
320 oil
Kinematic
Viscosity
at 1000c
30.5
Flash
point
00c min
190
Pour
point
00c max
-3
16.9
180
-9
15
200
-21
2.2 Four ball tester.
Four ball testing model shown by Fig.1 was
used to create wear and ASTM D 2783-82 standard
procedure is followed to find out load carrying
capacity of lubricants.
Fig 1: Four Ball Tester
3. Test Procedure
3.1 Cleaning & Preparation
Through clean steel balls, cup and ball holder
assembly by acetone and then dry in atmosphere.
Three balls are held in cup and locked by a locking
ring and then approximately 10ml lubricant is
International Journal of Advanced Engineering Technology
poured in cup. The Fourth ball which is fixed in a
chuck of vertical shaft, the lubricant cup assembly
brought in contact with the fourth ball and load is
applied by using hydraulic jack.
Graph
1:
representation
E-ISSN 0976-3945
SAE
90
oil
graphical
SAE 90 EP oil
4.5
4
Scar Dia in mm
3.5
3.2 Testing
The experiment is carried out by with ASTM D
2783-82 standard. The motor is run for 10 to 12
seconds and after that scar diameter on the test
balls is measured under the microscope. This scar
diameter is compared with average scar at
consecutively higher loads until welding occurs.
Hertz line is plotted using values plotted under
static condition using equation
Dh = 8.73*10-2 (P) 1/3
Table 2: Compensation Scar Diameter
Dh (mm)
Comp. Scar Dia.
0
0.18
0.236
.271
0.341
0.391
0.4306
0.463
Wear scar diameter was measured using
microscope and compare with average scar
diameter with compensation scar diameter if the
measured scar diameter is more the 5% from
compensation line continue up to weld point or
vice versa.
Weld point can be detected by noise of motor,
smoke or sudden drops in pressure.
Experimental Observations:
The following table shows tabulated results of
experiments conducted on Four Ball Tester.
Table 3: SAE 90 EP Oil.
Sr. No
1
2
3
4
5
6
7
8
9
10
11
12
Load
In Kg
154
164
170
200
250
275
315
360
400
450
500
520
Min Scar
Dia.(mm)
1.05
1.3
1.65
1.8
1.9
2
2
2.1
2.4
2.6
2.85
3.7
13
525
3.85
Series1
2
1.5
1
Fig. 2: Ball Assembly
P
Load in Kg
0
10
20
30
60
90
120
150
3
2.5
0.5
0
1
2
3
4
5
6
7
8
9
10 11 12 13
Applied Load in Kg
Fig3: Ball after Experiment
Results and Discussions:
Anti wear additives are used in oil to compensate
the oil viscosity loss at elevated temperature as
well as to provide better rheological properties to
the oil during operation, load wear index or load
carrying capacity of three oils determined using
four ball testers are as shown in Table 4
Table 4
Sr.
No
1
2
3
Sample
90EP
140 EP
SAE320
Load Wear
Index(kg)
80.79
78
24.7
Hertz Line Diag. for Different Oils:
Remark
Last non seizure
load
Immediate seizure
region
Graph 2: SAE 90 EP oil
Weld Load
IJAET/Vol.II/ Issue III/July-September, 2011/56-58
Weld
point(kg)
525
545
190
International Journal of Advanced Engineering Technology
Graph 3: SAE 140 EP oil
Graph 4: SAE 320 oil
REFERENCES:
1.
2.
3.
4.
5.
6.
7.
ASTM D2783-82 ( Four Ball Method)
A.V. Panter and P Ghosh: Effect of Viscosity
Modifiers on Viscometric and Wear
Performance
of
Lubricant;
Industrial
Tribology- Indian Institue of Petrolium
Dehradun, India, March 2000.
Hence Bloch- Practical lubrication for
industrial factories-Paramount Press (2009), PP
39-40.
H Li, K.K. Chao, J.L. Duda and E.E. Klaus: A
Study of Wear Chemistry and Contact
Temperature Using a Micorosample Four Ball
Wear Test, Tribology Transactions, Vol 42,
1999, P529-534
Vaintok, Pichugin & Malycega- Evaluation of
load carrying capacity of oils and lubricants or
cooling fluids in four ball friction tester
(1978)- Khimiya Tekhnologiya No 11, pp 2931.
M. Tech thesis of B.S. Kothavale
Principles of Tribology- J Halling, 1981.
IJAET/Vol.II/ Issue III/July-September, 2011/56-58
E-ISSN 0976-3945