ASTM D4683-96
(Test Method)Standard Test Method for Measuring Viscosity at High Shear Rate and High Temperature by Tapered Bearing Simulator
Standard Test Method for Measuring Viscosity at High Shear Rate and High Temperature by Tapered Bearing Simulator
SCOPE
1.1 This test method covers the laboratory determination of the viscosity of engine oils at 150°C and 1 X 10 s -1 shear rate using a tapered bearing simulator-viscometer (TBS Viscometer) equipped with a refined thermoregulator system. Older TBS units not so equipped must use Test Method D4683-87.
1.2 The Newtonian calibration oils used to establish this test method cover the range from approximately 1.5 to 5.6 cP (mPa[dot]s) at 150°C.
1.3 The non-Newtonian reference oil used to establish this test method has a viscosity of approximately 3.5 cP (mPa[dot]s) at 150°C and a shear rate of 1 X 10 s -1 .
1.4 Applicability to petroleum products other than engine oils has not been determined in preparing this test method.
1.5 This test method uses the centipoise (cP) as the unit of viscosity. For information on the equivalent SI unit, the millipascal second (mPa[dot]s) is shown in parentheses.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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An American National Standard
Designation: D 4683 – 96
Standard Test Method for
Measuring Viscosity at High Shear Rate and High
Temperature by Tapered Bearing Simulator
This standard is issued under the fixed designation D 4683; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope 3. Terminology
1.1 This test method covers the laboratory determination of 3.1 Definitions:
6 −1
the viscosity of engine oils at 150°C and 1 3 10 s shear rate 3.1.1 density—the mass per unit volume. In the SI, the unit
using a tapered bearing simulator-viscometer (TBS Viscom- of density is the kilogram per cubic metre, but for practical use
eter) equipped with a refined thermoregulator system. Older a submultiple is more convenient. The gram per cubic centi-
3 3
TBS units not so equipped must use Test Method metre is 10 kg/m and is customarily used.
D 4683 – 87. 3.1.2 Newtonian oil or fluid—an oil or fluid that at a given
1.2 The Newtonian calibration oils used to establish this test temperature exhibits a constant viscosity at all shear rates or
method cover the range from approximately 1.5 to 5.6 cP shear stresses.
(mPa·s) at 150°C. 3.1.3 non-Newtonian oil or fluid—an oil or fluid that exhib-
1.3 The non-Newtonian reference oil used to establish this its a viscosity that varies with changing shear stress or shear
test method has a viscosity of approximately 3.5 cP (mPa·s) at rate.
6 −1
150°C and a shear rate of 1 3 10 s . 3.1.4 shear rate—the velocity gradient in fluid flow. The SI
1.4 Applicability to petroleum products other than engine unit for shear rate is the reciprocal second (s-1).
oils has not been determined in preparing this test method. 3.1.5 shear stress—the motivating force per unit area for
1.5 This test method uses the centipoise (cP) as the unit of fluid flow. The area is the area under shear.
viscosity. For information on the equivalent SI unit, the 3.1.6 viscosity—the ratio between the applied shear stress
millipascal second (mPa·s) is shown in parentheses. and rate of shear. It is sometimes called the coefficient of
1.6 This standard does not purport to address all of the dynamic viscosity. This coefficient is thus a measure of the
safety concerns, if any, associated with its use. It is the resistance to flow of the liquid. In the SI the unit of viscosity
responsibility of the user of this standard to establish appro- is the pascal second; for practical use, a submultiple, millipas-
priate safety and health practices and determine the applica- cal second, is more convenient. The centipoise is 1 mPa·s and
bility of regulatory limitations prior to use. is customarily used.
3.1.6.1 apparent viscosity—the determined viscosity ob-
2. Referenced Documents
tained by this test method.
2.1 ASTM Standards:
3.1.6.2 kinematic viscosity—the ratio of the viscosity to the
D 4741 Test Method for Measuring Viscosity at High Tem- density of the liquid. It is a measure of the resistance to flow of
perature and High Shear Rate by Tapered-Plug Viscom-
a liquid under gravity. In the SI the unit of kinematic viscosity
eter is the metre squared per second; for practical use, a submultiple
D 5481 Test Method for Measuring Apparent Viscosity at
(millimetre squared per second) is more convenient. The
High-Temperature and High-Shear Rate by Multicell Cap- centistoke (cSt) is 1 mm /s and is customarily used.
illary Viscometer
3.2 Definitions of Terms Specific to This Standard:
3.2.1 calibration oils —Newtonian oils used to establish the
reference framework of viscosity versus torque from which is
This test method is under the jurisdiction of ASTM Committee D-2 on
determined the test oil viscosity.
Petroleum Products and Lubricantsand is the direct responsibility of Subcommittee
3.2.2 contact position—the rotor height when in rubbing
D02.07.0Bon High Temperature Rheology of Non-Newtonian Fluids.
Current edition approved Apr. 10, 1996. Published June 1996. Originally
contact with the stator.
published as D 4683 – 87. Last previous edition D 4683 – 95. 2
3.2.3 idling oil —an oxidatively stable Newtonian oil used
Available from Tannas Co., P.O. Box 327, Midland, MI 48640.
3 to minimize deposits on the rotor/stator operating surfaces
Annual Book of ASTM Standards, Vol 05.03.
when the instrument is held for long periods of time at
Annual Book of ASTM Standards, Vol 05.02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 4683
operating temperatures of 150°C at which other oils may in
reasonably short time decompose and leave residues.
3.2.4 non-Newtonian reference oil —a specially selected
non-Newtonian reference oil required to establish the proper
gap between the rotor and stator to produce an operating shear
6 −1
rate of 1 3 10 s .
3.2.5 reciprocal torque intersection, Rti—the rotor position
on the micrometer defined by the intersection of two straight
lines. These are generated by the reciprocal indicated torque
versus rotor height for the non-Newtonian NNR-03 and the
Newtonian R-400. The intersection indicates the rotor height at
6 −1
which the rotor/stator cell will generate 1 3 10 s shear rate.
3.2.6 rotor height (rotor position)—the vertical position of
the rotor relative to the stator and measured by the platform
micrometer.
3.2.6.1 Discussion—For most instruments, a mechanical
micrometer is used; the micrometer reading increases as the
rotor is lowered and approaches the stator. However, if an FIG. 1 Tapered Bearing Simulator-Viscometer
electronic micrometer is used, the micrometer reading de-
creases when the rotor is lowered.
3.2.7 stored position—the rotor position with the rotor 0.50
mm above the contact position.
3.2.8 test oil—any oil for which apparent viscosity is to be
determined.
4. Summary of Test Method
4.1 A motor drives a tapered rotor that is closely fitted inside
a matched stator. The rotor exhibits a reactive torque response
when it encounters a viscous resistance from an oil that fills the
gap between the rotor and stator. Two oils, a calibration oil and
a non-Newtonian reference oil, are used to determine the gap
distance between the rotor and stator so that a shear rate of
6 −1
1 3 10 s is maintained. Additional calibration oils are used
FIG. 2 Rotor, Stator, and Stator Housing
to establish the viscosity/torque relationship which is required
for the determination of the apparent viscosity of test oils at
150°C.
turntable has a projecting arm on which is mounted a contact
ball. The rotor is spun by the motor at a constant speed of 50
5. Significance and Use
or 60 r/s depending on the frequency of the alternating current.
5.1 Viscosity at the shear rate and temperature of this test
When the rotor encounters viscous resistance, the reactive
method is thought to be representative of the condition
force presses the ball against the platen of the load cell to
encountered in the bearings of automotive engines in severe
register the resistance given by the viscosity of the oil.
service.
5.2 The importance of viscosity at these conditions to 6.2 Console—The console shown in Fig. 3 contains the
engine lubrication has been addressed in many publications. power source for the load cell, thermoregulator circuit, heating
coil, and motor. It also contains the circuitry for regulating and
6. Apparatus
monitoring the temperature of the oil in the test cell, as well as
6.1 Tapered Bearing Simulator-Viscometer (Fig. 1)—a
the amplifier and digital readout of the load cell response.
viscometer consisting of a synchronous two-speed motor that
NOTE 1—The thermoregulator circuit of the TBS Viscometer has
drives a slightly tapered bearing in a matched stator (Fig. 2).
evolved as improvements have been made in the solid-state temperature
6.1.1 The motor and rotor are raised and lowered by means
controller and heater. To achieve the five-minute analysis time specified in
of a platform, which, in turn, is cantilevered from an elevator
this test method requires a late model solid-state controller with automatic
device. The gap between the rotor and stator is controlled by
reset coupled to a thermofoil heater with small heat inertia or a
adjustment of the platform height.
fast-responding thermoregulated oil bath.
6.1.2 The resistive force of the test oil is transferred to the
6.3 Air Circulation System—A flow of dry compressed air is
load cell by the turntable on which the motor sits. This
passed around the stator to provide supplementary cooling
when testing fluids of higher viscosity (greater than approxi-
5 mately 9 cP). Ports are provided in the stator housing for the
For a comprehensive review, see “The Relationship Between High-Temperature
Oil Rheology and Engine Operations,” ASTM Data Series Publication 62. circulation of compressed air.
D 4683
FIG. 3 Console
6.4 Glass Syringe, 50-mL, equipped with Luer needle lock evaluated, in some instances it may be desirable to filter the oil
fits the tip of the filling tube for injection of test oil into the test prior to injection. Care must be taken that air or other gas is not
cell. inadvertently injected into the operating cell.
6.5 Filter—A filter is used on the syringe to remove
9. Preparation of the Apparatus
particles capable of damaging the rotor/stator cell.
9.1 Directions for preparation of the tapered bearing
7. Materials
simulator-viscometer and console are supplied with the equip-
7.1 Calibration Oils are Newtonian oils of known kine- ment. One of the most important directions to be followed is
the alignment of the rotor/stator before initial use of the
matic viscosity and density at 150°C. The defined viscosities in
centipoise (mPa·s) are calculated by multiplying the kinematic viscometer.
9.2 With continuous use, a weekly room-temperature flush
viscosity in centistokes by the density in grams per cubic
centimetre. Approximate viscosities for the calibration oils are of the rotor/stator cell is recommended following directions in
11.4.
listed in Table 1. Certified viscosities are supplied with each
oil.
10. Calibration
7.2 Idling Oil—See 3.2.3.
7.3 Non-Newtonian Reference Oil is essential in setting the 10.1 Proceed to Section 11 if the operating position has
6 −1
rotor/stator gap to 1 3 10 s shear rate. An approximate already been established.
viscosity of a suitable non-Newtonian reference oil is given in 10.2 Activating the Console—Be sure the MOTOR switch
6 −1
Table 1. The certified viscosity at 1 3 10 s and 150°C is on the console is in the OFF position. Then, turn on the
supplied with the oil and is matched to the viscosity of POWER switch. Leave the console in this stand-by condition
reference fluid R-400 (see Table 1). for at least 1 h before using the tapered bearing simulator-
viscometer.
8. Sampling
10.3 Oil in Test Cell:
10.3.1 If there is no oil in the test cell, slowly inject 50 mL
8.1 A representative sample of test oil, free from evident
of the idling oil or other suitable oxidation-resistant fluid.
suspended solid material, is necessary to obtain valid results
10.3.2 When there is oil in the test cell, proceed with the
and to avoid lock-up and marring of the rotor/stator mating
determination of the stored position as described in 10.4. If this
surfaces. Do not draw test oil into the syringe from the bottom
position has been determined, proceed to 10.5.
of any container. When visible particulates are present in the
10.4 Determining the Stored Position:
oil, it is mandatory to remove them by filtration before the oil
10.4.1 Bring the operating temperature to 150°C by setting
is injected into the test cell (see 6.5). When used oils are
the thermostat on the console.
10.4.2 Be careful not to touch the hot upper stator surface
TABLE 1 Calibration and Reference Oils
when the following operation is performed. Slowly lower the
A
Viscometric Nominal Viscosity cP
Code No.
rotor into the stator by means of the height adjustment wheel
Characteristics (mPa·s) at 150°C
on the elevator assembly while turning the flexible shaft
R-200 Newtonian 1.9
connecting the motor and the rotor with the fingers until slight
R-300 Newtonian 2.8
B
R-400 Newtonian 3.5
rubbing contact is felt between the rotor and the stator. Then
R-500 Newtonian 5.3
slowly continue to lower the rotor in small increments (ap-
C
NNR-03 non-Newtonian 3.5
proximately ⁄10 of the smallest division or 0.001 mm until
A
Nominal viscosity values. Consult supplier for certified values.
B further turning is prevented (without forcing rotation)). This is
Matched to NNR-03.
C 8 −1
At 10 s (matched to R-400). the point of rubbing contact. Record the micrometer reading to
D 4683
the third decimal place (that is, estimate the last place from the 10.5.3.2 A different injection procedure may be used when
needle position between the minor division marks). All subse- the amount of test fluid is limited. Fill the syringe with 30 mL
quent readings of the micrometer dial will be to the nearest of fluid and make three 10-mL injections, waiting 10 s between
0.001 mm. each injection.
10.4.3 Raise the rotor to a position 0.50 mm (500 microme- 10.5.3.3 Note the time when the injection is completed.
tres) above the contact position. Record this reading as the 10.5.4 Stabilize the temperature at 150 6 0.2°C by regula-
stored position. tion of the temperature controller on the console. Air circula-
10.4.3.1 It is important to observe whether the micrometer tion to the stator housing may be required for supplementary
reading is 0.50 mm smaller or 0.50 mm larger than the reading cooling of fluids with viscosities greater than 9 cP. Five
at the contact position. For units that have mechanical mi- minutes after injection proceed to 10.5.5.
crometers, the reading for the stored position will be 0.50 mm
NOTE 2—A temperature controller with automatic reset and a thermo-
smaller than that recorded for the contact position. If an
foil heater are required to achieve 150 6 0.2°C within the specified 5 min.
electronic micrometer is used, the reading for the stored
10.5.5 Separate the load-cell/motor-turntable contact as in
position will be 0.50 mm larger than that recorded for the
starting (see 10.5.1), then shut off the motor. Reconfirm the
contact position. See 3.2.6.1.
rotor/stator contact position determined in 10.4.2. Now, raise
10.5 Determination of the Reciprocal Torque Intercept (Rti)
6 −1 the rotor to a position 0.10 mm
...
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