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 Products New Bearing Technologies |
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| TL Bearings / Super TF Bearings |
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Thanks to the new chemical composition and to the new treatment developed by NSK, it was possible to obtain a bearing with great advantages over standard ones. The STF bearings:
- increase by some times the service useful life when in contact with contaminated lubricant;
- increase service life when in contact with clean lubricant;
- increase by 30% fatigue resistance and by 40% gripping resistance;
- have dimensional stability superior to ASTM 52100 steel;
- have heating stability superior to conventional bearings, achieving, when at 160°C, a service life four times superior to conventional bearings.
For that performance, it was necessary to develop a new steel composition, the SAC2, which could allow the following characteristics:
- high content of arrested austenite;
- new type of thermal treatment that could present carbides and carbonitrites in small particles very well distributed in its structure.
Due to the arrested austenite, the mark generated on the race and on the rolling elements by the presence of impurities is minimized and the tension concentration generated around the teeth formed decreases. This STF bearing property increases bearing fatigue life.
Tension concentration around the tooth is expressed by the equation [P/P0 a (r/c)-0,24]. The meaning of their unknown quantities and illustration of an arbitrary mark is shown in Figures 1 and 2. As exemplified, the concentration ratio (P/P0) is inversely proportionate to (r/c), that is, the larger the radius (lower depth) and the smaller the mark size (c), the lower the tension concentration on this mark, This is the property attributed to the arrested austenite. Its control was named TF Technology. When enhancing this technology, the Super-TF was conceived.
High carbon steel is used in this bearing, as the objective is to obtain good purity and easy carbide acquisition. The alloy elements that constitute this steel are chrome, responsible for the formation of carbides, and molybdenum, responsible for diminishing carbine particles and distributing them evenly, creating a stronger structure. Figure 3 shows a comparison of carbide distribution between conventional steel (cemented) and SAC2.
At the side, there is a list of tests with the L44649/10 bearing (Figure 4), which indicates the superior service life obtained with the Super-TF bearings, under contaminated lubrication conditions.
Even in optimum lubrication conditions, Super-TF bearings present superiority, as shown on 6206 bearing (Figure 5).
In face of these tests, the supremacy of Super-TF bearings is evident, especially in contaminated lubrication environments (Figure 6).
Bellow we observe that, in deficient lubrication conditions, that is, protective film formation is insufficient, the contact between the rolling elements and the races is more effective. Hi-TF bearings present an extraordinary performance (Figure 7).
The TRIANGLE parameter represents the ratio between the oil film width and the surface rugosity.
In addition to increasing the bearing life under contaminated lubrication conditions, another factor that determines the Super-TF bearing superiority is its greater wear and gripping resistance (Figure 8).
The difference between Super-TF and Hi-TF technology bearings is the superficial hardness of these bearings and the alloy elements. Super-TF has 63~64 HRC hardness, and the alloy element used is molybdenum.
Super-TF bearings have NSK technology and were successful because they joined advanced technology and minimized costs.
These bearings are largely used in steel-iron works industries, as they resist to large loads and have a life superior to that of conventional bearings, even when exposed to impurities. This technology has been used worldwide, with excellent results.
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| Self-aligning roller bearings. |
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| A NSK relationship program with its Distributors. |
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