Standard accuracy of our products

Ball products from Sato Tekkou are manufactured through standardized manufacturing and quality control processes so that the customer can use them with ease, and only the top quality balls are delivered to our customers.

 

It manufactured based on many years of research on materials and experience in ball polishing, dimensional measurement is inspected and managed by our original sphere measuring instrument.

The basic rule of our quality assurance is to let our customers use our products with confidence.
We want our world customers to know that the products from Sato Tekkou are always reliable and made of the highest quality.

 

Rolling bearings - Balls JIS B 1501 excerpt

Terms and definitions
  • Single ball diameter, Dws
    The distance between two parallel planes tangential to the actual surface of a ball.
  • Deviation from spherical form
    The radial distance between the smallest circumscribed sphere and the greatest inscribed sphere, with their centers common to the least squares sphere centre.
  • Ball lot
    A definite quantity of balls manufactured under conditions presumed uniform and which is considered as an entity.
  • Ball grade (G)
    A specific combination of dimensions, form, surface roughness and sorting tolerances. Ball grade is indentified by the letter G and a number.
Measuring methods

  • Mean diameter of a ball and ball diameter variation
    The diameter necessary for determining the mean diameter of a ball and the ball diameter variation shall be measured with the ball placed between the horizontal plane and the stylus applied vertical to it from different directions.
    The mean diameter of a ball shall be obtained in the form of the arithmetic mean of the largest and smallest actual single diameters, and the ball diameter variation shall be obtained in the form of the difference between the largest and smallest actual single diameters.
    In this case, the measuring force shall be not more than 3N (306 gf).
  • Deviation from spherical form
    The method of evaluating the deviation from spherical form of a steel ball shall be in accordance with JIS B 1501 appendix A.
  • Surface roughness
    "For the surface roughness, measure the roughness around the equators of the steel ball with the instrument specified in JIS B 0651, as a rule, and take the center line mean roughness."

Standard accuracy of Steel balls

Unit:1μm=1/1000mm
Grade
(G)
Applicable range of ball size
(mm)
Ball diameter variation
(μm)
Sphericity
(μm)
Surface roughness Ra
(μm)
Lot diameter variation
(μm)
3 0.3~12 0.08 0.08 0.010 0.13
5 0.3~12 0.13 0.13 0.140 0.25
10 0.3~25 0.25 0.25 0.020 0.5
16 0.3~25 0.4 0.4 0.025 0.8
20 0.3~38 0.5 0.5 0.032 1
24 0.3~38 0.6 0.6 0.040 1.2
28 0.3~38 0.7 0.7 0.050 1.4
40 0.3~50 1 1 0.060 2
60 0.3~65 1.5 1.5 0.080 3
100 0.3~65 2.5 2.5 0.100 5
200 0.3~65 5 5 0.150 10

 

Standard accurancy of Plastic balls

Unit:μm
Ball diameter
(inch)
Ball diameter variation Lot diameter variation(MAX) Sphericity(MAX)
Precision grade High grade Precision grade High grade Precision grade High grade
3/32・1/8・5/32・3/16・7/32・1/4 ±20 ±50 7 10 5 (7)
 9/32・5/16・3/8・1/2・7/16・5/8 10 15 5 (12)
 3/4 ・ 7/8 ・ 1in 15 20 7 10 (15)
※ The sphericity of Polypropylene ball, PTFE ball, Polyethylene ball and UHMWPE ball are the number in ( ).