Wear Rate Simplicity ® Plain Bearings
Wear Rate vs. Life Expectancy
A rolling element linear bearing’s life expectancy is usually expressed in total inches or meters. A rolling element rotary bearing’s life expectancy is expressed in hours of operation. Both are also rated for average (L-50) and minimum (L-10) life. L-50 life is the average life that can be expected from 50% of rolling element bearings. In other words, 50% will not reach the average life expectancy. L-10 life is the minimum life (1/5 the average life) expected from 90% of rolling element bearings. In other words, 10% will not reach the minimum life expectancy. Theoretically they could fail upon installation. Plain bearings are not rated by a life expectancy but by the wear rate of the bearing material. Wear is greatly dependent upon the proper application of the bearing and material used. If it is not properly applied, it will fail. Failure, however, is subjective and dependent upon
specific application requirements. 0.002" running clearance may not be acceptable in one application while another may be able to run a bearing until the liner is completely worn through. The user may then rotate it 30 degrees and continue to run it. This broad range of acceptability makes it difficult to determine life expectancy. The first step is to determine what wear is acceptable for your application. Then utilizing the test data below, you can estimate the wear expected for your given application.
Wear Test Sample
19
5
#4
#2
#4
#2
4.5
Connection to Drive
#3
#1
#3
#1
Conducted by: Pacific Bearing ® Company Bearing Material: FrelonGOLD ® Shaft Material: Standard RC60 steel shafting Surface Finish: 8-12 Ra Speed: 140 fpm (70 cycles/min.; 1,680"/min.; 100,800"/hour; 2,419,200"/day) Stroke: 12"
Load: 10.87 psi (53 lb.) Bearings Used: FLN12 (3/4" open style bearings) Lubrication: None Total Wear to Bearing Material: FrelonGOLD = 0.00042" Note: Wear is an average of totals taken from 4 bearings per carriage.
FrelonGOLD ® Linear Wear Test
FrelonGOLD
Wear in Inches
0.005 0.004 0.003 0.002 0.001 0 0.006
Inches of Travel
Hours Operated
30 60 90 120 150 180 210 240 270 300 330 360 390 420 450 480 510 540 570 600 630 660 690 720 750 780 810 840 870 900 930 960 990 1020 1050
pbclinear.com • Engineering Your Linear Motion Solutions 141
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