Development and volume production of new ceramic ball bearing (for the first time in Japan)

JTEKT Corporation (hereinafter called “JTEKT”) has newly created a tagline “Key of your operation Koyo” for the bearing brand “Koyo”. JTEKT contributes to every industry as an indispensable partner to solve customers' problems through working with customers and to provide benefits.
JTEKT has developed a new ceramic ball bearing for motors by adopting a new rolling element (ball) material whose thermal expansion is more similar to that of the inner and outer ring material than conventional types.
For motor bearings which require measures against electrolytic corrosion an insulation property equivalent to silicon nitride (conventional material) is now possible in addition to a wider range of temperature adaptability by reducing clearance variation between the inner and outer rings and balls due to temperature changes.
The first mass production in Japan of this bearing for which the new ceramic material is employed is planned for June 2016.

1.Product features

(1) Insulation property similar to the conventional ball material (silicon nitride)

(2) Adaptability to a wider range of temperatures thanks to smaller changes in clearance compared with the conventional ball material (silicon nitride)

2.Detailed description

One of the characteristics of an electric motor is that when a high frequency current is used during operation, that current generates a harmful voltage. If the voltage exceeds a certain limit, it flows through the extremely thin oil film on the rolling contact area and causes a spark (electric discharge) in the bearing. In this case, a phenomenon called electrolytic corrosion occurs, in which the rolling surface, etc. of the bearing is locally melted, causing an abnormal noise and a decline in the bearing’s lifespan.
Therefore, an insulation measure is required for the bearing. The most reliable insulation measure is the use of ceramic as the ball material, for which silicon nitride is normally used.
The new ceramic material employed in the developed product has an insulation property equivalent to silicon nitride. In addition, its coefficient of linear expansion (amount of material length increased per temperature increase by 1 degrees Celsius) is similar to that of the metal used as the inner and outer ring material. This property reduces the clearance variation between the inner and outer rings and balls due to temperature changes and provides adaptability to a wider range of temperatures during operation.

3.Sales Plan

4.Production Plant

Tokushima Plant

5.Product photo