ISO3290/AISI
We manufacture our product to meet all major standards (ISO 3290, AISI Std.10, JIS B1501).

Our trained engineers also work closely with our customers to develop products most suitable for their applications.
Technical Definitions
Grade A specific combination of dimensional form and surface roughness tolerance
Nomintal 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.
Sphericity The greatest radial distance in any radial plane between a sphere circumscribed around the ball surface and any point on the ball surface.
Surface Rounghness 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 Rc 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 0.010
5 0.13 0.13 0.25 0.014
10 0.25 0.25 0.50 0.020
20 0.5 0.5 1.0 0.032
40 1.0 1.0 2.0 0.06
60 1.5 1.5 3.0 0.08
80 2.0 2.0 4.0 0.1
100 2.5 2.5 5.0 0.1
200 5.0 5.0 10 0.15
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： micronmeter(μm) VDL： Lot diameter variation
VDS： Ball diameter variation Ra： Unit of surface roughness(μm)
W： Deviation from spherical form(Roundness) Refernce： ISO 3290-2001