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austenite grain boundaries in 52100 bearing steel
by conventional heat treat
austenite grain boundaries in 52100 bearing steel
by FA process
conventional vs. FA series bearings
NTN Corporation (Japan) is the latest bearing manufacturer to launch an entirely new product line, leveraging advances in materials technology.
With its new FA series tapered roller bearings, NTN says it has developed the world's first specialized heat treatment to produce ultra-fine austenite grains in standard 52100 bearing steel.
The proprietary FA heat treatment process, said NTN, produces austenite grains less than half the size found in conventionally heat-treated bearing steel.
The practical impacts of creating fine-grain austenite 52100 steel are to substantially increase its fatigue strength and its fracture strength.
NTN has implemented the material improvement from FA heat treating as a 40% reduction in the FA series bearing's sectional area, compared to an equally-rated conventional bearing.
Reducing a bearing's dimensional envelope by 40% while still maintaining performance, said NTN, is proving particularly important in upcoming automotive applications. Transmissions are a key future market for smaller, high-performance, bearings.
Mechanical and metallurgical advances have allowed more compact automobile transmissions without sacrificing power handling. Now a key focus of automotive bearing manufacturers is the future market, suppling smaller transmission bearings to complete the picture.
Prior to the FA bearing, however, the fatigue strength of standard carburized steel limited the bearing's ability to keep downsizing to meet these ever-smaller transmission packaging requirements.
An important side effect of the 40% smaller bearings is the concurrent reduction in mass, another key design consideration for drivetrain engineers dealing with efficiency and fuel consumption issues.
In addition, NTN said the FA bearings exhibit superior anti-seizing characteristics when loaded hard against the back face. This had been a problem in the past when downsized bearings were produced with a standard heat treating process.
Beyond immediate applications in automotive transmissions, future applications for the FA series will include gear boxes, transfer cases and wheel bearings.
| Product Model | Inside Diameter | Outside Diameter | Thickness |
| CR8-1B IKO | 12.7 | 10.9 | |
| CR8-1 IKO | 12.7 | 10.9 |