A cycle is defined as two stroke lengths up and back. Electronic timers can be used to terminate the test. If a cycle-counter is available, this may be used instead of the timer, in which case Eq 2 will be used. Humidity can vary with air flow and in different parts of the same room, so the humidity sensor should be located as close to the test specimens as reasonably possible, in such a way that the air movement conditions are the same for humidity sensor as for the test specimens.

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A cycle is defined as two stroke lengths up and back. Electronic timers can be used to terminate the test. If a cycle-counter is available, this may be used instead of the timer, in which case Eq 2 will be used. Humidity can vary with air flow and in different parts of the same room, so the humidity sensor should be located as close to the test specimens as reasonably possible, in such a way that the air movement conditions are the same for humidity sensor as for the test specimens.

In full immersion, liquid-lubricated tests, the bath temperature shall be measured and reported. Calibration 7. Statically applied loads shall be kept constant within a maximum deviation of For example, permitted static error of a During oscillating tests, the normal force may vary slightly about the mean value due to the dynamics of the machine.

This variation is to be expected. WarningDue to inertial effects, differences in the loading and fixturing method become more significant as the oscillating frequency of the test is increased, and harmonic frequencies characteristic of the test machine must be avoided when selecting the oscillating frequency. Depending on the machine, a fixture which applies a calibrating load in line with the normal point of contact between the ball and flat should be used. Procedure 8.

In a polished condition, the surface should be as free as possible from preparation artifacts such as grinding-induced cracks, gross grinding marks, and grain pull-out. Surface roughnesses of 0. NOTE 1Certain materials could be adversely affected by cleaning in solvents. Deviations from the prescribed cleaning procedure are permitted, but they shall be described in the report. It is possible that during mounting, some contamination was inadvertently placed on them, and this final cleaning will help alleviate the problem.

Inspect the ball tip with a hand lens after it is mounted to ensure that there are no defects in the contact area. The height of the specimen or mount may require adjustment to ensure that this condition is fulfilled. Apply the prescribed test load. Confirm that the desired oscillating speed has been set before turning on the motor. No further reproductions authorized. G 05 severity should be selected. If neither procedure in 8.

See the reporting requirements in Section 10 for reporting exceptions to Procedures A and B. NOTE 2This procedure requires full-immersion lubrication. If other methods, such a controlled drip feeding system, are used to simulate certain applications, the provisions of 8.

Bath temperature shall be controlled to within a maximum deviation of A fresh supply of lubricant shall be used for each test unless the objective is to evaluate the effects of used lubricants on friction and wear. Remove the normal force to recheck the zero point on the friction force recording system. To measure the wear, it is necessary to clean the specimens in such a way that the surface features are not altered. For unlubricated tests, a concentrated jet of air may be used to dispel the debris from the worn area of the specimens.

For liquid-lubricated specimens, ultrasonic cleaning in a suitable solvent may be used. Specimens shall be thoroughly dried. Any ball movement within the holder during the test invalidates the test results. Similarly, any slippage of the flat specimen in its fixture invalidates the test results.

Modifications to the specific test conditions prescribed in Procedures A and B may be used for conducting such tests; however, in reporting the results, the specific parameters which are not in compliance with one of the standard testing procedures shall be specifically noted. A statement such as the following may then be used: These tests are not in full compliance with the provisions of Test Method G, Procedure A, because the normal force in these tests was All other provisions of Test Method G have been followed.

Measurement and Calculation of Wear 9. In Fig. Refer to the following which applies. Pin scar measurements may be made by removing the ball specimen holder and placing the wear scar portion under a reflecting microscope.

A calibrated ocular or a photomicrograph of known magnification may be used to measure scar dimensions. WarningFor lubricated tests in which there is minimal wear, it is possible to be misled in reading the apparent wear scar diameter of the ball tip optically because of elastic recovery. A small, shallow annulus surrounding the elastically deformed area may give the impression of wear, whereas little or no appreciable wear has actually occurred.

Profilometry may be used to determine whether the wear scar is flat and consequently whether Eq 3 and Eq 4 can be used. G 05 FIG. NOTE 3Various methods have been used to measure the wear volumes of non-flat ball tips.

In most cases, the width and depth of the wear scar on the flat specimen will be relatively uniform throughout its length. If wear is nonuniform, six cross-sectional profiles shall be obtained to compute the average track cross-sectional area.

Generally, in calculating wear volume of the flat specimen, the minor geometric errors associated with the direction-reversal points at each end of the track can be neglected. WarningIt is not recommended that continuous wear depth data obtained from position-sensing gages be used because of the possible complications arising from entrapped debris, thermal expansion due to frictional heating, hydrody4 Whitenton, E.

Cross-sectional profiles may be obtained using a stylus-type instrument or its functional equivalent. On the printed profile made across the wear track, a straight line is drawn between the unworn areas on both sides of the wear scar and the cross-sectional area of the wear groove, below that reference line, is used to compute the wear volume.

The cross-sectional area may be determined by planimetry, through the use of computerized digitizing tablet, or by importing the surface trace data directly into a computer program which permits the measurement of areas under profiles. Report Also, report any unusual frictional behavior, as indicated in Test parameters to be reported should conform with either Procedure A or B. If procedures other than A or B are used, the report should explicitly state so, listing the conditions which are different than those described in 8.

G 05 and root-mean-square surface roughness. Commercial designations for materials should be given, if applicable. If a lubricant is used, provide its commercial name or other description, and any other properties needed to identify the source and traceability of the lubricant. Grain size and percent porosity of specimens may be reported, if applicable.

If reporting grain size, indicate whether the grain size is nonuniform or duplex. See Test Methods E and E Additional guidelines for reporting data are found in Guide G NOTE 4Quantities which have been measured on the same lot used for fabricating wear test specimens should be distinguished from those obtained on other lots of material or handbook values and assumed to apply to the given test specimens.

Tests involving proprietary materials are specifically excluded from reporting compositions or processes; however, material lot numbers and as many specific identifiers as possible shall otherwise be provided. See 9.

Photomicrographs of the scars should be included, if available. Report the standard deviation. The following equation may be used: S c 5 0. If the calculated contact stress exceeds the hardness of either material, there will be permanent plastic deformation and elastic conditions do not apply. Kinetic friction coefficient can be calculated from:.


Wear & Abrasion

Tribometer Instruments Lab Services Rotative Application Notes Linear Wear Friction Process: Linear wear friction test reproduces the linear reciprocating motion found in many real-world tribology mechanisms. A flat, pin or ball tip is loaded onto a test sample with a precise weight. The test samples can be of varied shape such as cylindrical as long as there is a flat zone of a certain length in the direction of movement. The length of the track can be adjusted prior to the start of measurement.


ASTM G133 - 2005

The wear resulting from this mode of movement may differ from that experienced by the same materials sliding continuously in only one direction unidirectional sliding even for comparable durations of contact. Test loads and speeds are to be determined by the severity of the proposed application or purpose of the testing. Either of two sets of testing conditions designated Procedures A and B may be used. Scope 1. The direction of the relative motion between sliding surfaces reverses in a periodic fashion such that the sliding occurs back and forth and in a straight line. The principal quantities of interest are the wear volumes of the contacting ball and flat specimen materials; however, the coefficient of kinetic friction may also be measured using the method described. This test method encompasses both unlubricated and lubricated testing procedures.





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