Technical Calculation Software

File Name	Catalog Page	File Size	Uncompressed File Size
Linear Guides ・ Ball Screws Technical Calculation Software Ver.2.0	-	6.79 MB	6.85MB

Life

Ball screw's life is defined as a total number of rotations it can sustain without showing any deterioration caused by repeated stress on the ball or rolling surfaces. Ball screw life can be calculated with Basic Dynamic Load Ratings using the following formula.

Life Calculation Example

Application Condition

・Ball Screw Model	BSS1520 (O15, Lead 5)
・Average Axial Load Pm	250N
・Average Rotational Speed Nm	2118（min-1）
・Load Factor fw	1.2

Calculation Details

Basic Dynamic Load Rating C for BSS1520 is 4400N,

Therefore the life will be 24824 hours.

Axial Load

Axial loads applied on a ball screw will differ for acceleration, low speeds, and deceleration phases, and can be calculated with the following formula.

- Axial Load Calculation-
A Constant Velocity Phase --- Axial Load (Pb) = μWg
B Acceleration Phase --- Axial Load (Pa) = Wα + μWg
C Deceleration Phase --- Axial Load (Pc) = Wα - μWg

* For vertically mounted application, omit "μ" from the calculation.
μ: Linear Bearing Friction Coefficient (0.02 for Linear Guides)
W: Moving Mass N
g: Gravitational Acceleration 9.8m/s2
α: Acceleration
(*) Acceleration (α) = (Vmax / t) x 10-3
　　　　Vmax: Fast Feed Speed mm/s
　　　　t: Accel./Decel. Time s

Average Axial Load and Average Rotational Speed Calculations

Average Axial Load and Average Rotational Speeds are calculated based on motion profiles used.
A profile example shown in Table 1. can be calculated with the formula 2.

Average Axial Load and Average Rotational Speed Calculation Example

Application Condition

Motion Profile	Axial Load	Rotational Speed	Time Ratio
A	343N	1500mim	29.4%
B	10N	3000mim	41.2%
C	324N	1500mim	29.4%

Calculation Details

(1) Average Axial Load

Therefore, Average Axial Load Pm will be 250N.

(2) Average Rotational Speed

Therefore, Average Rotational Speed Nm will be 2118min.