ABMA Standard

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We manufacture our product to meet American Bearing Manufacturer Association Standard (ABMA Std. 10-1989). Our trained engineers also work closely with our customer to develop product most suitable for our customers' application.
ABMA Std. 10-1989 Technical Definition
Grade
  A specific combination of dimensional form and surface roughness tolerance. A ball grade is designated by a grade number.
Nominal Ball Diameter
  The diameter value that is used for the purpose of general identification of a ball size. Measured by two parallel plane tangent to the surface of the ball.
Mean Diameter of a Ball
  The arithmetical mean of the largest and the smallest single diameter of the ball.
Lot Mean Diameter
  The arithmetical mean of the mean diameter of the largest ball and that of the smallest balls in the lot. Lot is the definite quantity of ball manufactured under uniformed condition.
Lot Diameter Variation
  The difference between the mean diameter of the largest ball and that of the smallest ball in the lot.
Diameter Tolerance
  The maximum allowable deviation of any ball mean diameter from the nominal ball diameter
Deviation from Spherical Form
  The greatest radial distance in any radial plane between a sphere circumscribed around the ball surface and any point on the ball surface.
Surface Roughness
  Surface roughness consists of all those irregularities such as crack, cuts and dent, which surface relief. And it is conventionally defined within the area where deviation of form are eliminated.
Hardness
  The measure of resistance to penetration of the ball surface or truncated flat of the ball by a specific indenting shape.
Case Depth
  The distance measured radially from the surface of the ball to the point where the ball hardness becomes HRC 50. This term is applicable to case hardened ball only.
Grade and Tolerance
 
Grade VDS W VDL Ra
3 0.08 0.08 0.16 0.012
5 0.13 0.13 0.25 0.02
10 0.25 0.25 0.50 0.025
20 0.5 0.5 1.0 0.04
40 1.0 1.0 2.0 0.08
48 1.2 1.2 2.5 0.08
60 1.5 1.5 3.0 0.095
80 2.0 2.0 4.0 0.12
100 2.5 2.5 5.0 0.125
200 5.0 5.0 10 0.2
300 7.5 7.5 15 X
500 12.5 12.5 25 X
800 20 20 40 X
1000 25 25 50 X
2000 50 50 100 X
 
Unit: micrometer (｣gm)
VDS : Ball diameter variation
 W: Deviation from Spherical form
VDL: Lot diameter variation
 Ra: unit of surface roughness
Reference: ABMA Std. 10-1989
Hardness and Crashing Load
 
Size Chrome Steel Ball Carbon Steel Ball
inch mm Hardness Crashing Load (kg) Hardness Crashing Load (kg) Case Depth(mm)
  0.5 HV 700~860   HV 700~860   0.1
1/32" 0.794    
  1.0    
1/16" 1.588 180 170 0.4
  2.0 310 250
3/32" 2.381 380 300

0.5

  2.5    
  3.0    
1/8" 3.175 56.0~ 60.5 700 56.5~60.5 500 0.6
5/32" 3.969 56.5~61.0 1100 57.0~61.0 800
  4.0    
3/16" 4.762 57.0~61.5 1500 57.5~61.5 1100 0.8
  5.0    
7/32" 5.556 57.5~61.5 2000 58.0~62.0 1400 0.9
  6.0 58.0~63.0    
1/4"
 6.350 58.0~63.5 2600 1800 1.1
5/16" 7.938 59.5~64.5 4100 60.0~64.0 2700
3/8" 9.525 59.5~65.0 5900 60.5~64.5 3700 1.4
  11.0   61.0~65.0   1.7
  12.5 60.5~65.5   61.5~65.5   1.8
1/2 12.7   6200 1.9
5/8" 15.875 61.0~66.0   62.0~66.0   2.0
3/4" 19.050    
7/8" 22.225    
1" 25.4    
             
 
Foot Note: Hardness readings taken on spherical surfaces are subject to the corrections
  shown in Table 1
  1. Hardness : measured by HRC & referenced by AFBMA 10-1989 & JIS B1501
2. Crashing Load : P = 85.9 x D1.773 (for chrome only) & JIS 9404 (for carbon steel ball
    bearings)
3. Case Depth : Referenced by AFBMA 10-1989 (only for carbon steel ball bearing)

 

Table 1: Hardness Correction Table (ABMA 1989-10)
Corrections To Be Added To Rockwell "C" Readings Obtained On Spherical Surfaces
Metric Sizes
 
RC Readings Ball Diameters
6mm 8mm 10mm 12mm 15mm 20mm 25mm
20 12.8 9.3 7.6 6.6 5.2 4.0 3.2
25 11.7 8.4 6.9 5.9 4.6 3.5 2.8
30 10.5 7.5 6.1 5.2 4.1 3.1 2.4
35 9.4 6.6 5.4 4.6 3.6 2.7 2.1
               
40 8.0 5.7 4.5 3.8 3.0 2.2 1.8
45 6.7 4.9 3.8 3.2 2.5 1.8 1.4
50 5.5 4.0 3.0 2.6 2.0 1.4 1.1
55 4.3 3.1 2.3 1.9 1.5 1.0 0.8
60 3.0 2.2 1.7 1.2 1.0 0.6 0.4
               
65 1.9 1.9 0.9 0.6 0.4 0.2 0.1
               
 Inch Sizes
 
RC Readings Ball Diameters
1/4" 5/16" 3/8" 1/2" 5/8" 3/4" 1"
20 12.1 9.3 7.7 6.1 4.9 4.1 3.1
25 11.0 8.4 7.0 5.5 4.4 3.7 2.7
30 9.8 7.5 6.2 4.9 3.9 3.2 2.4
35 8.6 6.6 5.5 4.3 3.4 2.8 2.1
               
40 7.5 5.7 4.7 3.6 2.9 2.4 1.7
45 6.3 4.9 4.0 3.0 2.4 1.9 1.4
50 5.2 4.0 3.2 2.4 1.9 1.5 1.1
55 4.1 3.1 2.5 1.8 1.4 1.1 0.8
60 2.9 2.2 1.8 1.2 0.9 0.7 0.4
               
65 1.8 1.3 1.0 0.5 0.3 0.2 0.1
               
 
Hardness readings taken on spherical surfaces are subject to the corrections
  shown in Table 1