Page 96 - needle bearings

Drawn cup needle roller bearings
NTN

thickness) and thereafter the inscribed circle
Bearing Tolerances and Measuring Methods diameter (Fw) is measured using a plug gauge or a
The outer ring of drawn cup needle roller bearing is so taper gauge to evaluate the bearing accuracy.
thin-walled that deformation thereof to a certain extent is Tables 4 to 7 show the dimensional tolerances for the
unavoidable in the manufacturing processes, particularly bore diameter of each ring gauge and the inscribed circle
in the heat-treating process. However, the outer ring is so diameter (Fw) each of standard metric series drawn cup
designed that it is reformed normally from such needle roller bearings Type HK and BK, heavy load
deformation when being press-fitted in a housing with series Type HMK (metric series), inch series Type DCL,
specific dimensional accuracy and, as a result, it can and inch series HCK for application to universal joints.
have the accuracy required to fulfill its specific function. When measuring the inscribed circle diameter of roller,
Hence, it is meaningless to measure the the low tolerance for the inscribed circle diameter shall be
dimensional accuracy of bearing itself before being applied to the dimension at "GO" side and the value of
press-fitted. So, the following measuring method is the high tolerance for the inscribed circle diameter plus
used; a bearing to be measured is press-fitted in a (+) 2Жm shall be applied to the dimension at "NOT GO"
linkage of specific dimension (20mm or more in wall side in compliance with the relevant ISO standard.

Table 4 Dimensional tolerance for inscribed circle diameter (Type HK and BK) Table 5 Dimensional tolerance for inscribed circle diameter (Type HMK)
Unit : mm Unit : mm
Nominal inscribed Nominal outer Ring gauge Tolerance for Nominal inscribed Nominal outer Ring gauge Tolerance for
circle dia. ring outer dia. bore dia. inscribed circle diameter circle dia. ring outer dia. bore dia. inscribed circle diameter
Fw D High Low Fw D High Low
3 6.5 6.484 3.016 3.006 8 15 14.995 8.028 8.013
4 8 7.984 4.022 4.010 9 16 15.995 9.028 9.013
5 9 8.984 5.022 5.010 10 17 16.995 10.028 10.013
6 10 9.984 6.022 6.010 12 19 18.995 12.034 12.016
7 11 10.980 7.028 7.013 14 22 21.995 14.034 14.016
8 12 11.980 8.028 8.013 15 22 21.995 15.034 15.016
9 13 12.980 9.028 9.013 16 24 23.995 16.034 16.016
10 14 13.980 10.028 10.013 17 24 23.995 17.034 17.016
12 16 15.980 12.034 12.016 18 25 24.995 18.034 18.016
12 18 17.980 12.034 12.016 19 27 26.995 19.041 19.020
13 19 18.976 13.034 13.016 20 27 26.995 20.041 20.020
14 20 19.976 14.034 14.016 21 29 28.995 21.041 21.020
15 21 20.976 15.034 15.016 22 29 28.995 22.041 22.020
16 22 21.976 16.034 16.016 24 31 30.994 24.041 24.020
17 23 22.976 17.034 17.016 25 33 32.994 25.041 25.020
18 24 23.976 18.034 18.016 26 34 33.994 26.041 26.020
20 26 25.976 20.041 20.020 28 37 36.994 28.041 28.020
22 28 27.976 22.041 22.020 29 38 37.994 29.041 29.020
25 32 31.972 25.041 25.020 30 40 39.994 30.041 30.020
28 35 34.972 28.041 28.020 32 42 41.994 32.050 32.025
30 37 36.972 30.041 30.020 35 45 44.994 35.050 35.025
35 42 41.972 35.050 35.025 37 47 46.994 37.050 37.025
40 47 46.972 40.050 40.025 38 48 47.994 38.050 38.025
45 52 51.967 45.050 45.025 40 50 49.994 40.050 40.025
50 58 57.967 50.050 50.025 45 55 54.994 45.050 45.025
55 63 62.967 55.060 55.030 50 62 61.994 50.050 50.025
60 68 67.967 60.060 60.030

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