Balls, Cylindrical Rollers
HRB balls are manufactured from carbon chromium steel and have a hardness within the range 58 to 65 HRC. The balls within each class are graded according to their deviation from the normal diameter, the grading tolerances being dependent on the class of ball and its size. A consignment of balls of the same nominal diameter and class may include packages of one grade only, or of more than one grade.
The standard design of roller has a cylindrical surface which is slightly relieved towards the roller ends, in order to prevent damaging edge stresses. The rollers are graded according to the mean deviation from the nominal diameter and nominal length. Each grade is packed separately and the package marked to show the mean deviation from the nominal diameter and nominal length. A consignment or rollers of the same nominal size may contain rollers of only one grade or of more than one grade.