The maintenance cycle of the Orca™ Series motors may be of great importance to a select few applications, particularly those in factory settings with considerable side load. The exact service life of the bushings is entirely dependent upon the loading characteristics of the application, and some loading conditions never require bushing replacement. Fortunately, IGUS provides a calculator on the life cycle for the bushings in the motors.
The mechanical interface between stator and the shaft is a thin plain flanged bushing. The IGUS product code is GFM252625. This bushing has a wall of 0.5mm thick, which accommodates the cutting edge force efficiency of these motors.
This article will teach how to find the life cycle of the bushings using the IGUS Calculator.
The first page of the Igus Calculator can be found annotated below:
In this case, the bushing side load is entirely dependent upon the location of the force on the side of the stator, and the length of the shaft has no effect on the side loads. The equations for the bearing side loads are as follows:
F_{b1}=FaF/L F_{b2}=aF/L
Where F is the side load of a motor simplified to a point load, this may have to be calculated from an aggregate of different loads. a is the location of the force from the first bushing, and L is the spacing of the bushings, from center point to center point. This is dependent on the length of the Stator. The following table shows these lengths for each stator type:
Table 1: Bearing Spacing of Stators 

Orca Series Variant 
L, Bearing Spacing 
Orca6 
147.9mm 
Orca15 
376.5mm 
So as an example, if 100N was place on an Orca6 at 70mm from the first bushing:
F_{b1}=100N70mm*100N156.9mm=55.39N F_{b2}=70mm*100N/156.9mm=44.61N
In this case, the bearing load is now dependent on the length and position of a shaft, this is the use case that amplifies the exerted force onto the bushings. The equations for the bearing side load is as follows:
Fb1 = F + aF/L Fb2 = aF/L
Where F is the side load of a motor simplified to a point load, this may have to be calculated from an aggregate of different loads. a is the location of the force on the shaft measured from the centre point of the first bushing, and L is the spacing of the bushings, from centre point to centre point. This is dependent on the length of the stator. Table 1 contains the values of the bearing spacing.
It’s important to note that a is not equal to the shaft throw, and it does not measure from the end of the stator. The distance from the centre of the bushing to the end of the stator is 12.5mm.
It’s also important to note that Iris Dynamics recommends supporting lateral loads with linear bearings to reduce friction and increase the life cycle of the bushings.
The next page of the calculator focuses on the motion type and profile. A motor with minor and slow movements will maintain healthy bearings longer than the same motor undergoing larger and quicker motions. The annotated page can be found below:
The final page for variable entry selects the housing and shaft materials. The Housing is a glass filled Polypropylene, the shaft is 304 Stainless Steel, and the recommended wear limit is 0.25mm.
After filling the data from the previous pages, it is now possible to find the bushing lifetime. The bushings are G300. The service life can then be determined. The corresponding number of cycles can be found by reverse calculating using the variables on the Motion Page.
The accurate service life is entirely dependent on a comprehensive use case analysis. The full life of a bearing may only be realized with clean surfaces, free of excess humidity and excess heat. This calculation can provide valuable estimations on the effect of load and motion on the maintenance cycle.
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