UMT
Hardware Configuration: Block-on-Oscillating-Ring
Test Using Micro-Tribometer mod. UMT
ASTM
D 2981-94 (reapproved 1998)
and
ASTM D 3704-96 (reapproved
2001)
Standard
Test Method for Wear Properties of Solid Lubricants and Greases in Oscillating
Motion
Summary of
Test Method:
This test method
covers the evaluation of wear and durability of lubricants and coatings under
oscillating motion using a block-on-ring lower drive on the Micro-tribometer
mod. UMT-2. A coated steel test ring (lower specimen) of a 35-mm diameter and
8.15-mm width is assembled on a horizontal shaft of the lower drive. A steel
test block (upper specimen) of 15.75-mm length and 6.35-mm width is held in the
block holder on the loading carriage. The ring is oscillated around its axis at
a specified arc. In the beginning of the test, the specimens are worn-in under a
small load, the main test is performed under the test load.
The D2981 specifies
the ring material (4620 steel, HRC 58-63) and surface finish (RMS of 500 to 750
nm), the block material (01 steel, HRC 58-63) and surface finish (RMS of 100 to
200 nm), as well as the oscillating speed of 87.5± 1 cycle/min at a 90º arc,
the wearing-in period of 1 min, the loads during wearing-in and the main test.
It includes friction force measurements during the test, and then evaluates the
wear life as a number of cycles required for the frictional force to rise to a
predetermined value.
The D3704
recommends to vary the specimen hardness and surface finish, the test load,
speed and arc of oscillation to simulate field conditions. It has no
requirements for in-situ measurements, and evaluates the wear after the test by
measuring the width of a wear scar on the test block.
The UMT allows for
monitoring during the test the actual dynamic normal load, friction force and
friction coefficient, and depth of wear. Optionally, it can measure additional
parameters of contact acoustic emission and temperature.
UMT
Hardware Configuration:
·
4”
Mounting Block – PN M30C116
·
Model
DFH-100 Dual Friction/Load Sensor
-
range 0.1 to 100 kg
·
Upper
Specimen Holder for Blocks
- for sensors mod. DFH
·
Upper
Specimen Test Block
- package of 5
·
Lower
Block-on-Ring Drive
-
mod. BHHM
·
Lower
Specimen Test Ring
-
package of 5
·
Optional
Additional Sensors
-
mod. AE-5 Contact Acoustic Emission Detector
-
mod. TMR-150 Temperature Measurement & Recording
-
mod. RTD Temperature Sensor
UMT Software
Test Setup:
UMT Options
File:
Load the options file which contains
settings for the block-on-ring drive and the 100 kg force/load sensor.
Test
Sequence:
The Test Sequence should consist of 3
sheets.
Sheet 1 is for settling time for the
carriage to establish the initial normal load.
Carriage
- applies a 13 kg Constant Force for a Duration of 10 sec.
Spindle – Velocity
is
0 revs/min.
Slider
–
is idle.
Sheet 2 is a 1-min wear-in period
Carriage
- applies a 13 kg Constant Force for a Duration of 1 min.
Spindle – Velocity
is
7.96 revs/min, Move- increment, Distance 0.25 rev, and Direction-
cycl.e
Slider –
is idle.
Sheet 3 is the wear-life test period
Carriage
- applies a 50 kg Constant Force for a Duration of 5 hours or as
needed to achieve significant wear.
Spindle – Velocity
is
7.96 revs/min, Move- increment, Distance 0.25 rev, and Direction-
cycle.
Slider
–
is idle.
Data
Collection:
The following should be checked under DataFile:
Fx – Friction Force
Fz – Normal Force
T – Time
Z1 – Carriage Position (Used to determine Wear Depth)
AE input – Acoustic Emission (optional)
Te input – Temperature (optional)
Report:
Use
the Viewer program to plot test results.
Select
the parameters to be displayed by checking
the
appropriate box under Parameters on the Viewer screen.
For
viewing COF plots of reciprocating tests check the Fz box, click on the Symmetry
button, click on the Peak Detect button, and then check the COF box.
Multiple test results can be viewed at the same time as in the example below.
 |
 |