Calculating the Permissible Axial Load

Mounted Horizontally

With ordinary conveyance systems, the axial load (Fa_n) applied when horizontally reciprocating the work is obtained by the equation below.

Mounted Vertically

With ordinary conveyance systems, the axial load (Fa_n) applied when vertically reciprocating the work is obtained by the equations below.

Static Safety Factor

Static Safety Factor per Basic Static Load Rating (Excluding Models HBN-V, HBN-K (KA), HBN, and SBKH)

For ball screws, a static safety factor as defined by formula 30 based on the calculated maximum axial load and static load rating must be considered. Vibrations, impacts, or inertia due to starting and stopping may result in an unexpectedly large load. Therefore, please confirm that a sufficient static safety factor has been ensured when selecting a model. Table 21 shows guideline values for the static safety factor.

Table 21: Static Safety Factor (f_s)

Load conditions	Lower limit of f_s
Without vibrations or impacts	2
With vibrations or impacts	5

Permissible Load Safety Margin (Models HBN-V, HBN-K (KA), HBN, and SBKH)

The permissible load Fp in the axial direction is fixed for high-load ball screw models HBN-V, HBN-K (KA), HBN, and SBKH. Therefore, please select a model with a calculated maximum axial load (Fa_max ) that does not exceed the permissible load (Fp). Permissible load (Fp) indicates the maximum axial load that the high-load ball screw can receive, and this range should not be exceeded.

¹The basic static load rating (C₀a) is a static load with a constant direction and magnitude whereby the sum of the permanent deformation of the rolling element and that of the raceway on the contact area under the maximum stress is 0.0001 times the rolling element diameter. With the ball screw, it is defined as the axial load. (Specific values for each ball screw model are indicated in the dimensional tables for the corresponding model.)
²The maximum load in the axial direction calculated on Calculating the Axial Load is applied to the maximum axial load (Fa max ).
³Vibrations and impacts are typically caused by factors such as acceleration and deceleration, sudden starting and stopping, vibrations and impacts from an external machine, and changes in processing power over time.