February 20, 2007

Development of a World Class "Ultra High Speed Sealed Angular Contact Ball Bearing" for Machine Tool Main Spindles

[Achieving the world's highest speed using a new grease (SE-1) and an optimized internal design]

NTN corporation (hereafter NTN) has developed an ultra high speed sealed angular contact ball bearing, which enables the world's highest rotational speed (dmn value : 1.7 million) in machine tool main spindles. It is available with 20 to 100mm bores as NTN's "BNFS series".

In order to improve bearing durability, oil lubrication such as an air oil mist is generally used for the high-speed main spindles where the dmn value exceeds 1.4 million, Therefore the machining of piping on the housing and an external lubrication unit are necessary. To eliminate this, grease lubricated high-speed bearings have been in high demand.

On the "BNFS series" developed by NTN, the bearing internal design is optimized to account for ultra high speed and temperature rise while maximizing bearing rigidity. A new urea type grease [SE-1]which improves the grease life, is adopted as the lubricant. Furthermore a specially developed material is used to improve anti-seizure properties under grease lubricated high speed and high contact pressure applications.

The merit of "BNFS series" lies in a reduction of environmental burdens because of an environmental friendly grease lubrication and a cost reduction due to the fact that bearing washing, grease packing and an external lubrication unit are not necessary.

[Features]

1.	Sealed angular contact ball bearing with the world's fastest dmn value.
	[ dmn value of 1.7 million : 20% improvement compared with the conventional bearing ] Running speed 40,000min-1 with a bearing bore 30mm Running speed 13,500min-1 with a bearing bore100mm
2.	Bearing washing and grease packing are not necessary during the bearing mounting
3.	External lubricant supply unit is not required

[Application]

Machine tool main spindles (Machining center and Tapping machine)

[Reference]

dmn value = dm (Bearing pitch dia. in mm) × n (Running speed in min-1) Example : When a bearing with 42.5mm dm pitch, runs at 40000min-1 speed, dmn value is 42.5 × 40000 = 1.7milliom

[Product photo]

[Structure] "BNFS Series" Cross- section drawing of ultra high speed sealed angular contact ball bearing

[Sales points]

[Technical Data]

1.	Optimized internal design	⇒	High speed & Low heat generation
2.	Newly developed grease[SE-1]	⇒	High speed & Long life
3.	Specially developed material for rings	⇒	Improved anti-seizure property

[Attributes]

1.	Reduction of environmental burdens
	Expanded use of environment friendly grease [dmn value 1.4 million⇒1.7 million]
2.	Reduction of working time
	Work for bearing washing and greasing is not necessary
3.	Cost reduction
	No external lubrication unit is required

[Example of applications]

Small machining center, Tapping machine, etc.

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