Slewing Bearing: Kaydon VS LILY Bearing

Slewing bearings, also known as slewing rings or turntables bearings, facilitate rotational movement while supporting heavy loads.

They are essential in various applications like cranes, wind turbines, and excavators. 

Kaydon and LILY are renowned manufacturers of slewing bearings.

In this article, a comparison has been made between Kaydon and LILY regarding single row four-point-contact slewing bearings MTE-210T, with dimensions of ∅8.268 x ∅14.686 x1.575 inches.

The comparative analysis reveals differences in MTE-210T’s raw material, heat treatment, grease, size, rotation accuracy and static load.

Understanding these differences can help users select the most suitable slew bearings for their specific needs.

Raw Material Comparison

Inner & Outer Ring

 Table 1  Inner & Outer Ring Raw Material Comparison

Balls

Table 2  Balls Raw Material Comparison

Since the GCr15 material of the LILY brand is considered an equivalent material to the 100Cr6 of the KAYDON brand in the market, there will be similarities in mechanical properties and chemical composition.

However, the specific heat treatment processes and hardness requirements may differ, which could affect the performance and overall durability of the balls and the bearing.

Heat Treatment Comparison

Inner & Outer Ring

Table 3  Inner & Outer Ring Heat Treatment Comparison

Table 4  Kaydon vs Lily Bearing in Surface Hardness

Fig 1  Slewing Bearing Surface Hardness Illustration

Table 5  Lily Bearing in Surface Flatness 

Balls

Table 6  Balls Heat Treatment Comparison

Grease Comparison

Kaydon

Table 7   Appropriate Grease Lubricants for Kaydon Slewing Ring Bearings

Table 8  Typical Characteristics of BP Energrease LS-EP 1 (Subject to usual manufacturing tolerances.)

LILY

No. 2 lithium ester (Great Wall) is used as the grease lubricant of LILY bearing. LILY can customize grease as requested by the clients.

Table 9   Typical Characteristics No. 2 lithium ester (Great Wall)

Visual Inspection

Heat Treatment Marks

Fig 2  LILY VS Kaydon in Heat Treatment Marks

The difference lies in the result of different machining processes for raceway:

1. Kaydon: selective hardening for raceway after finishing machining;
2. Lily: final surface grinding after raceway selective hardening, treatment marks removed.

Teeth Marking

Fig 3  Actual Marking Color of LILY's and Kaydon's Real Bearings

1. The marks on teeth are indicated for teeth with minimum gear backlash. The color is defined by bearing supplier.
2. This is special for gear assembly.

Position of Filler Plug and Grease Fitting

Fig 4  Position of Filler Plug and Grease Fitting  of LILY's and Kaydon's Real Bearings

1. Filler is used for balls installation and plugged in after that.
2. The position between filler and grease fitting is depend on bearing supplier and there is no relation to each other and not affect for utilization.

Gear 

Fig 5  Before and After Use of LILY's Bearing

Raceway of Inner Ring

Fig 6   Various Raceway Failure Mode of Kaydon (Source: SKF Bearing damage evaluation guide.pdf)

No wear is observed inside the inner ring raceway of a failure Lily bearing.

Fig 7  Inner Ring Raceway of a Failure Lily Bearing

Raceway of Outer Ring

Fig 8   Various Outer Raceway Failure Mode of Kaydon (Source: SKF Bearing damage evaluation guide.pdf)

No wear is observed inside the outer ring raceway of a failure Lily bearing.

Fig 9   Outer Ring Raceway of a Failure (Lily Bearing)

Balls

No wear, corrosion, cracks, etc. were found on the steel balls of a failure Lily bearing.

Fig 10   Balls of a failure (Lily bearing)

Size

Both Kaydon and LILY manufacture slewing ring bearings ranging for outside diameters of just 4 inches up to 282 inches (10 cm to 7.2 m). 

See Testing Report of PN MTE-210T.

Table 10   Testing Report of PN MTE-210T

Rotation Accuracy

Axial Clearance

Table 11  Test Result of Axial Clearance

Test Results of Rotation Accuracy (Axial Run-out)

Table 12  Test Result of Rotation Accuracy

Field Testing of Axial Static Load Capacities

1. Static axial load test of LILY’s MTE-210T Slewing bearing was performed on May 10 in Shanghai Bearing Technology Research Institute (a leading 3rd party institute of bearing industry in China);
2. An axial loading of 3 Ton was applied on both sample of LILY's and Kaydon's bearings.

Test Methods 

1. Initial Inspection: 
   Conduct an initial inspection of the sample for the following items: internal diameter size, rotational accuracy (end runout of inner ring, diameter runout of inner ring, end runout of outer ring), and axial play.

Fig 11   Initial Inspection

2. Axial Static Load Test: 

Attach the sample to the test rig, initially load with 1kN for 3 minutes, zero the indicator, then increase to 20kN at 0.2kN/second, hold for 3 minutes, note total deformation, and finally, decrease at the same rate to 1kN to measure permanent deformation.

Fig 12  Recording the value of the numerical rebound

3. Re-inspection of Sample: 
   After the axial static load test is completed, re-inspect the sample for internal diameter size, rotational accuracy (end runout of inner ring, diameter runout of inner ring, end runout of outer ring), and axial play.

Fig 13 Re-inspecting the sample

4. Axial Static Load Test Result Comparison

 Table 13   Axial Static Load Test Result

5. Disassembled Checking

(1) Kaydon’s sample is not disassembled in accordance with the client requirement;

(2) LILY’s sample is disassembled, there are some curve tracks been found along circumferential direction on the groove in visual checking.

Thrust & moment curve comparison between Kaydon and LILY

The curves presented by both of LILY’s and Kaydon’s bearing  almost matched ( invert coordinate system is needed for LILY).

Fig 14  Kaydon's Thrust & Moment Curve

Fig 15  LILY's Thrust & Moment Curve

Remarks: 1.   The curve for LILY bearing was established from software called “SlewBrg V3.0”;

2. The curve for Kaydon bearing can be found from Kaydon catalogue of pg.70  “Kaydon _Catlog_390.pdf”;
3. More information about how LILY buildup the thrust & moment curve can be found from “Establishment of MTE-210T LILY slew bearing loading curve.pdf”.

Conclusion

The comparative analysis between LILY and Kaydon slewing rings focuses on several key aspects, including raw material, heat treatment, mechanical properties, and performance under load.

LILY's material has a higher carbon content, which generally leads to better hardness and wear resistance, contributing to better load-bearing capacity.

LILY’s grease use can be tailored to customers’ requirement.

Both Kaydon and LILY slewing ring bearings have shown similar  performance under load.

The choice between them should be based on the specific requirements of the application, including the need for strength, wear resistance, and temperature tolerance.

Regular maintenance and adherence to best practices will help ensure the longevity and reliability of the bearings.