Page 312 - MiSUMi 2025

Economy series Ball Screws Selection Guide
Ball Screws

Step 4 Allowable Rotational Speed Check

The rotational speed of the ball screws must be less than the allowable rotational
speed. If it exceeds the allowed rotational speed, the thread and the nut will be affected
in the following way.
Screw Shaft: When the allowable rotational speed is exceeded, resonance will begin at
a unique oscillating frequency and this might disable operation. (Figure 3)
Nut: If the orbital speed of the steel balls inside the nut becomes large, it is possible Figure 3 Resonating Ball Screw
that the circulation components will be damaged by the impact force. (Figure 4)

Allowable Rotational Speed 4 Steel Ball 1 Screw Shaft
3 Refers to the allowable rotational speed that is 80% or less of the critical speed that matches the Recirculation Part 3
rotational speed of a ball screw at which there is a unique oscillation possessed by the screw shaft.
The ball screw rotational speed is decided by the necessary travel speed and ball screw lead.
Ball Screws / Lead Screws To decide the allowable rotational speed, it is necessary to consider the following two elements. 2 Nut Lead Screws Ball Screws /
1. Critical speed for the rotating shaft
2. Limit rotational speed of the balls circulating inside the nut
D For details, see P.B-032 on the Catalog.
3 Steel Ball
Step 5 Life Check Figure 4 Ball Screw Circulation Structure (Tube Style)
Rolled Ball Screws In order to use the equipment beyond the expected life, life calculations are required. Screws Rolled Ball

P.03-009 Operating Hours of Ball Screws P.03-009
This refers to the total revolutions, time, or distance up until chipping begins to occur
Precision Ball Screws balls. The lifespan of the ball screw is calculated from the basic dynamic load rating. Screws Precision Ball
due to fatigue causes by some kind of repetitive stress on the ball rolling surface or
See Figures 5 and 6 for expired parts that have chips.

and 90% of the screws achieve 1 million rotations (10 ) without flaking in its operating
6
P.03-027 When a certain group of the same ball screws are operated with a certain axial load P.03-027
life, such axial load is defined as a basic dynamic load rating.
Ball Screw Supports / Motor Brackets D For details, see P.B-033 on the Catalog. Threads inside nut (Magnification of Figure 5) Motor Brackets Ball Screw Supports /
Figure 5 Thread Inside Nut
Steel Ball
P.03-047 P.03-047
Lead Screws Lead Screws

P.03-058 Unused Figure 6 Flaking on Ball Screw Components Flaking on Threads P.03-058
Unused
Flaking on steel balls
Lead Screw Nuts Q When choosing, it is necessary to ensure the temperature impact and rigidity is suitable for the Nuts Lead Screw
usage environment and selection criteria. For details, see P.B-029~B-035 of the catalog technical
pages and choose a ball screws that is suitable for the purpose of use.
P.03-077 Q Lubrication (grease inspection and replenishment) P.03-077
Lead Screw Supports The grease forms an oil film on the ball screw’s screw shaft, rolling surface inside the nut, and surface of the balls and acts to reduce Supports Lead Screw
friction and prevent heat damage. MISUMI ball screws are filled with grease before shipping, however after commencing use, it is

used at shipment and do not mix with other greases.
P.03-079 necessary to perform regular and appropriate inspection and grease replenishment. When adding grease, use the same grease that was P.03-079
• Guides for inspection and grease replenishment
Lead Screw Stop Plates / Position Indicators After 2~3 months of operation, if the grease is very dirty, we recommend to remove the old grease and fill with new grease. Subsequent Position Indicators Lead Screw Stop Plates /
inspection intervals are recommended to be every 6 months, however, we recommend this timing be adjusted to an interval appropriate
for the usage environment.
Here is some representative grease which can be applied to Ball Screw.
P.03-081 • Available grease in the market P.03-081
-Alvania Grease S2 made by Showa Shell Sekiyu) / Multemp Grease PS2 made by Kyodo Yushi)
-ET-100 (Made by Kyodo Yushi) / LG2 (Made by NSK) / AFF (Made by THIK)
Each grease has different performance, please select suitable grease to meet to the operating condition.
03-015 03-016