Experiments on Ultrasonic Lubrication Using a Piezoelectrically-assisted Tribometer and Optical Profilometer

The overall goal of the following experiment is to investigate the dependence of friction and wear reduction on linear velocity in ultrasonic lubrication. This is achieved by first conducting tests on a modified pin on disc TER while recording real-time friction forces during the tests as a second step, an optical profilometer is utilized to characterize wear, providing 2D and 3D profiles, surface roughness and volume losses in the grooves. Next, friction and wear reduction at three.

Linear velocities are quantified using measured friction forces and calculated wear rates. The results show that ultrasonic lubrication reduces effective friction force by up to 62%and surface wear by up to 49%Friction reduction decreases as linear velocity increases while wear reduction remains essentially constant at the three linear velocities. Considered Ultrasonic lubrication is a well-established technology for reducing and in fact controlling the effective friction coefficient between sliding objects.

It works by vibrating one or both objects at ultrasonic frequencies that is frequencies above 20 kilohertz. Ultrasonic lubrication has been implemented in manufacturing processes such as extrusion and a wire drawing being a solid state lubrication technology. It can be used in applications where traditional lubricants are undesirable.

For example, in space To build the necessary TER first, assemble the chuck motor subsystem, perform this assembly on an isolation table. First level, a DC motor with shims and fix its position using struts and bolts. Then position the support frame around the motor.

Next, connect the spline shaft to the motor shaft using a key continue by sliding the support plate onto the spline shaft. Then position the thrust needle roller bearing on the support plate. Lubricate the bearing with cutting fluids if needed, to finish assembling the chuck motor subsystem.

Connect the chuck to an adapter plate using three bolts and tighten the bolts. Place the chuck on the support plate through the thrust needle roller bearing. Put the gimbal assembly with the support frame in place.

It has a horizontally oriented load cell connected to the gimbal arm by a wire to measure friction. Next, assemble the piso electric actuator. First, insert a three inch threaded rod through the Piso electric stack.

Secure it with washers and nuts, leaving about one eighth inch of the rod available at one end. Then tighten the nuts to preload the stack. Next, connect the long exposed threads to the gimbal arm using nuts and washers.

Thread an acorn nut onto the other end of the piso actuator for setup purposes, non-testing. Then insert the disc to the chuck and adjust the position of the disc so that the acorn nut is in contact with the top of the disc and the gimbal arm is level. Adjust the position of the gimbal assembly so the nut contacts the disc at about 25 millimeters from the disc's center.

To finish, tighten all the bolts in the setup and attach the setup to the computer. The testing discs and nuts must be cleaned wearing gloves. Use ethanol to clean the surface of the testing disc and the acorn nut.

Now remove the acorn nut used for setup purposes. Then thread on the new clean nut and firmly tighten it down. Once tightened, check the alignment and tighten the chuck so the disc is firm and make sure the acorn nut is firmly tightened to the actuator.

It is critical to firmly tighten the acorn nut to the epi electric actuator, or it could become loose during the test resulting in the ultrasonic vibrations not being transmitted and thus becoming ineffective. To set up the test, apply a normal load between the test nut and disc by hanging a two newton weight on one hook that connects to the gimbal arm. Then hang another two Newton weight on the other hook that connects to the gimbal arm.

This provides a horizontal pretension to the load cell. Next, connect the actuator and the signal generator to the amplifier. Set the signal generator to provide a continuous sinusoidal signal.

Use an amplitude of three volts and a frequency of 22 kilohertz. The resonance frequency of the piso actuator include a DC offset of three volts to prevent tension in the pizo actuator. Now start collecting data to measure the reduced friction force.

Turn on the amplifier and set the gain to 15, which corresponds to an actual gain of 4.67. Next, turn on the motor and set the rotational velocity as needed. Run the test for three hours, then turn off the motor and amplifier and end the data acquisition.

Remove the acorn nut and test disc and label the test disc with the test conditions. Always use a new nut and test surface for each test. To measure the intrinsic friction, use the same linear velocity with the amplifier and signal generator off.

Repeat the same testing for other linear velocities. There should be six wear grooves created in the end. In preparation, clean the test discs immediately before measurements.

As before, It is important to clean the sample discs before perter measurements, and you loosely attach the wear particles or foreign matter on the wear groove. Were compromised the position of the measured profiles and volume loss. Next, make eight evenly distributed marks around the rim of the disc.

Now open the profilometer software using the software. Raise the lens so that there is sufficient clearance between the lens and the sample platform. Then level the sample platform and place a piece of lab wipe on the platform.

Gently place the sample on top of the tissue with one of the eight marks facing the front of the barometer. Set up scanning parameters in the software. Scan the groove and save the profile images and roughness data.

Then turn the sample counterclockwise until the next mark faces the front of the profilometer and repeat the process for the remaining marks. Once done with one disc, repeat the measurements for the remaining five discs. The friction force was sampled at 400 hertz using two second sampling windows mean values of measured friction were calculated and plotted against the distance the pin travels.

Intrinsic friction forces are represented with dots while friction forces with ultrasonic vibrations are shown. With xs, friction force remained virtually constant once a steady state operation was achieved. Next, the reduction percentage at each linear velocity was plotted against the distance traveled by the pin.

Ultrasonic vibrations reduced the steady state friction force at each tested linear velocity. However, the benefits decreased as the linear velocity increased where grooves with and without ultrasonic vibrations were compared. It can be seen that grooves appear more uneven and non-reflective when ultrasonic vibrations were applied.

3D profiles, surface roughness values and volume losses of the grooves were obtained from the profilometer scans. The 3D grooves with ultrasonic vibrations were narrow, rough, and shallow when compared to those without ultrasonic vibrations. This supports the notion that the ultrasonic vibrations reduce wear, wear rates and surface roughness parameters were smaller when ultrasonic vibrations were present, which is also an indicator of wear reduction.

The wear reduction percentage remained virtually constant as the velocity increased. After watching this video, you should have a good understanding of how to conduct ultrasonic lubrication tests on a modified pin on disc ter and characterize where using optical prophy Using this ultrasonic friction and wear reduction can be studied with respect to not just linear velocity, but also key parameters such as normal stress, material combinations, and ultrasonic power consumption.