November 17, 2008

Development of ‘Long life ball screw’ applicable to severe environments

[Contributing to the electrification of automobiles.]

NTN Corporation (hereafter NTN) has developed a ‘Long life ball screw’ for automotive electric actuators, with significantly longer life than conventional products.

With the progression and development of high performance or low fuel consumption vehicles, electric motor driven systems are becoming increasing more common than conventional hydraulic systems for automotive applications such as engine and transmission. Those applications using ball screws are growing, however, operational environments are becoming more and more severe and reduction in size and weight is required. Consequently, improving durability of these components becomes necessary. On the other hand, in most cases for automotive applications, not only main axial loads but also moment and radial loads act on ball screws. As a result, ball screw sizes inevitably become larger because ball screws designed using conventional methods have insufficient durability.

With the newly developed ball screw, the conventional standard design was reviewed and the durability performance was improved by use of ball sizes exceeding lead* and optimization of tread groove specifications. Thereby, significantly longer life than that of the conventional product was achieved even in severe conditions where complex loads were applied.

It can be expected that this highly reliable and efficient ball screw will become widely used, with the progression of electrification in automotive systems. NTN will recommend this product to customers and market it globally.

*Lead: Travel distance in one revolution of ball screw

[ Features ]

		[In comparison with NTN's conventional product]
a. Life	:	Improved by 6 times (compared to the same size product)
b. Size	:	Down sized axially by 7% (compared to products with similar life )
c. Mass	:	Reduced by 30% (compared to products with similar life )

[ Applications ]

Various electric actuators for engine control, transmission etc.

[ Product appearance photos ]

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