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#268 Ball Screws -5: Accuracy and Grade

Category : Linear Motion Components
December22, 2016

JIS B 1192 defines ball screw accuracy of the precision ball screws. This section explains the accuracy and grade of ball screws.

The major factor in determining ball screw accuracy is called "lead accuracy". (See the Note* for details.) The two evaluation items of "lead accuracy" and "appearance" are called "ball screw grades" and used for the classification of quality.

Notes*
∗Lead accuracy: [Fig.1] defines the deviation and variation for the effective travel distance of a nut or the actual mean lead of the effective thread length of a screw shaft, variation for any 300 mm interval in the effective thread length of a screw shaft, and variation for one revolution within the effective thread length. The permissible values are listed in [Table 1] and [Table 2].
∗Appearance: The surface of a ball screw should be free from cracks or defects, such as scratches, burr, and rusting that will compromise its intended function.

[Fig.1] Lead accuracy of precision ball screws (JIS B 1192)

[Table 1] Variation and actual mean lead deviation of the precision ball screws (permissible value),[Table 2] Variation of the precision ball screws (permissible value)

= JIS =
-The accuracy grades for ball screws are classified into six grades (C0, C1, C3, C5, C7, and C10).
-Screws in the four grades (C0, C1, C3, and C5) are referred to as precision ball screws. The rest of the grades (C7 and C10) are defined as standard ball screws.

= ISO3408-1: 1991 =
-The accuracy grades for ball screws are classified into five grades (1, 3, 5, 7, and 10). Grade 1, 3, and 5 screws are designed for positioning. Grade 7 and 10 screws are designed for feeding.

MISUMI USA eCatalog

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