The linear wear test, ASTM G, reproduces the linear reciprocating motion found in many real-world tribology mechanisms. ASTM G – Designation: G – 02 Standard Test Method for Linearly Reciprocating Ball-on-Fla. ASTM G – – Download as PDF File .pdf), Text File .txt) or read online. ASTM G –
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A number in parentheses indicates the year of last reapproval. A superscript epsilon e indicates an editorial change since the last revision or reapproval. 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? This test method encompasses both unlubricated and lubricated testing procedures. The scope of this test atm does not include testing in corrosive or chemically aggressive environments.
The values given in parentheses are for information only. 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.
Current edition approved Nov. Originally approved in Last previous edition approved in as G —95 e1. Summary of Test Method 4. These specimens move relative to one another in a linear, back and forth sliding motion, under a prescribed set of conditions. The normal load, stroke length, frequency and type of oscillation, test temperature, lubricant if anytest duration, and atmospheric environment including relative humidity range are selected from one of two procedures.
The manner in which the velocity varies with time is determined by the design of the mechanism which drives the ball or? 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. The ball is rigidly mounted and has a spherical tip which moves back and forth across the surface of a polished?
Use of a spherical tip alleviates the alignment problems associated with? A provision is made for applying a uniform normal force load to the contact between the ball and the? Temperature measurement and control capability is provided to heat and monitor the?
The tangential force can be measured continuously during oscillating contact and used to obtain friction coefficient data. For example, a Scotch yoke drive mechanism can provide a smooth, sinusoidal velocity pro? Stepper-type motors may also be used provided that the motion is smooth and uniform.
If a bearing ball is used, it shall be clamped tightly enough to prevent slippage during the test. The ball holder should be rigid enough so that the periodic reversal in the sliding direction does not result in tilting or other misalignment of the contact.
A variety of shapes and con? The primary criterion is that the coupon present a? G — 02 friction forces generated during sliding. Calibration of the friction force see section 7. Since the direction of the friction force changes rapidly during the test, traditional strip-charttype recorders may be too slow to follow these changes at high frequencies of reciprocation. A commercial version of this machine is available with a signal conditioner to rectify, and output the root-mean-square friction force to a strip-chartrecorder or to a computerized data acquisition system.
The method of sensing and recording friction force during the test shall be described in the testing report. To compute the sliding distance in metres or number of cycles, use the following: Warning—Due to inertial effects, differences in the loading and?
Depending on the machine, a?
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 1—Certain materials could g133 adversely affected by cleaning in solvents. Deviations from the prescribed cleaning procedure are permitted, but they shall be described in the report. A cycle is de? Electronic timers can be used to aetm 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? In full immersion, liquid-lubricated tests, the bath temperature shall be measured and reported.
ASTM G133 – 05(2016)
Statically applied loads shall be kept constant within a maximum deviation of For example, permitted static error of a aetm 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. It is possible that during mounting, some contamination was inadvertently placed on them, and this? 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 ful?
Apply the prescribed test load. The procedure appropriate for the given materials and test severity should be selected. If neither procedure in 8. NOTE 2—This procedure requires full-immersion lubrication.
If other methods, such a controlled drip feeding system, are used to simulate certain applications, the provisions of 8. A statement such as the following may then be used: All other provisions of Test Method G have been followed.
Universal Mechanical Testers for Tribology Testing in the Automotive Industry
Measurement and Calculation of Wear 9. 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 re? A calibrated ocular or a photomicrograph of known magni? Bath temperature shall be controlled to within a maximum deviation of A fresh g33 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 aastm not altered. For unlubricated tests, a concentrated jet of air may aatm 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 asm holder during the test invalidates the test results. Similarly, any slippage of the? Assuming a spherical wear volume, the height of material removed can be calculated from D as follows: Warning—For 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 axtm.
A small, shallow annulus surrounding the elastically deformed area may give the impression of wear, whereas little or no appreciable wear has actually occurred. NOTE 3—Various methods have been used to measure the wear volumes of non-?
Linear Reciprocating (ASTM G)
In most cases, the width and depth of the wear scar on the? If the areas of the three initial pro? If wear is nonuniform, six cross-sectional pro? Generally, in calculating wear volume of the? Warning—It 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, hydrodynamic lift, and tribochemical?
On the printed pro? 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 pro? Wear volume of the?
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 astmm should explicitly state so, listing the conditions which are different than those described in 8. Information shall be sufficient to establish their source, chemical composition, processing history, surface 1g33, 5 5 Whitenton, E.
G — 02 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 4—Quantities which have been measured on the same lot used for h133 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 speci? If the calculated contact stress exceeds the hardness of either material, there will be permanent plastic deformation and elastic conditions do not apply.