Limiting Load Diagrams

This page provides the life calculation formulas and static limiting load diagrams for AXCR cross roller bearings. This information is used to determine the expected life and safe operating range of the bearing under given load conditions.

Life Time and Load Safety Factor

General Notes

The following calculations are generally used for simple application cases and provide good approximations.

myonic Calculation Service

Through myonic's special calculation program, rated life can be precisely calculated. Data required for calculation includes:

Application details (drawings, sketches, technical specifications)
Workpiece dimensions and weight
Load cycle details (cutting forces, speeds, operating times)

Dynamically Equivalent Load

In applications with radial and axial loads as well as speeds affecting the bearing, all loads can be combined into a single equivalent load. This "dynamically equivalent load" can be calculated using the following formula:

P = X · (F_r + ^2M/_{D_pw}) + Y · F_a

When F_a / (F_r + 2M/D_pw) ≤ 1.5	X = 1, Y = 0.45
When F_a / (F_r + 2M/D_pw) > 1.5	X = 0.67, Y = 0.67

Symbol	Description	Unit
P	Dynamically equivalent load	[N]
F_r	Radial load	[N]
F_a	Axial load	[N]
M	Torque	[Nmm]
D_pw	Roller pitch diameter	[mm]
X	Radial load factor	-
Y	Axial load factor	-

Nominal Life Time

The nominal life can be estimated using the following formula. The nominal life represents the number of revolutions (in millions) at which 90% of all bearings of the same type under the same load and speed will achieve before material fatigue occurs:

L = (^C/_P)^10/3

Symbol	Description	Unit
L	Nominal life	[10⁶ revolutions]
C	Dynamic load rating (C_r for primarily radial load, C_a for primarily axial load)	[N]
P	Dynamically equivalent load	[N]

Equivalent Static Load

The equivalent static load combines all loads generated during static application into a single load. This load acts on the bearing in the same way as the actual effective load:

P₀ = (F_r + ^2M/_{D_pw}) + 0.44 · F_a

Symbol	Description	Unit
P₀	Equivalent static load	[N]
F_r	Radial load	[N]
F_a	Axial load	[N]
M	Torque	[Nmm]
D_pw	Roller pitch diameter	[mm]

Static Load Safety Factor

The static load safety factor describes the relationship between the static load rating C₀ (depending on the application, C_0a or C_0r can be used) and the equivalent static load P₀. Different static load safety factors are required depending on the respective operating conditions. For more precise information, please contact our technical support.

S₀ = ^C₀/_P₀

Symbol	Description
S₀	Static load safety factor
C₀	Static load rating
P₀	Equivalent static load

Limiting Load Diagram Explanation

The static limiting load diagrams are used to:

Check whether the selected bearing size is primarily subject to static loads
Determine the tilting moment M_k that the AXCR can absorb (in addition to axial load)

The static limiting load diagrams take into account the static load safety factor S₀ ≥ 4 for the outer ring as well as screw and bearing ring strength.