1)      resistance to abrasion

The inertia of ceramics results in its resistance to abrasion.

2)      long lifetime

The fatigue lifetime of the fully ceramic KOYO bearing is espected to be 10-50 times than the plain bearing, with the partial ceramic bearing 3-5 times.

3)      high level of the rotation speed and acceleration

The operation can be under the condition of dn>3,000,000. Also, the slipping, abrasion and heat can be decreased.

4)      high temperature resistance

The fully ceramic KOYO bearing can work with the temperature more than 500℃.

5)      great rigidity

Because of the large elastic modulus of ceramic bearing, the rigidity is 15%-20% times than the plain one.

6)      little lubration needed

When the lubricating oil is light or absent, the lubricating ability of the oil ceramic KOYO bearing is still higher than the plain one, because of the low friction factor of the ceramic.

7)      low seating torque

Depending on the whole structure, the ceramic KOYO bearing is 1/3 times shorter than the plain one.

1)      middle hardenability steel

The oil quenching critical diameter of this kind of steel is 40-60mm. Chrome-molybdenum steel and chrome manganese steel are two kinds of usual types. Common names are 35(jrMn.42CrMo.35L:rMnV.40CrMn.35CrMnSi. 30CrMnsi.35(:rMnTi.40crMnTi.40crNi and so on. The chrome-molybdenum steel has the high hardenability, high high-temperature strength, good organizational stability, removing temper brittleness and so on. 42CrMo is used to make quenched and tempered parts of high strength required and large section, such as gear, spindle of steam turbine generator and connecting rod subjected to large loads . Also, 42CrMo can be used to make parts which often work with the temperature less than 50℃. The chrome manganese steel has the high hardenability and strength, but the toughness not decressed. 30(:rMnsi has the properties of high strehgth and good solderability, so it is used to make important parts, such as compressed tablet of high pressure blower and grinding spindle with high-speed loads.

2)      high hardenability steel

The oil cooled critical diameter of the steel is 60-100mm. Common material names are 30Mn2MoW.40CrMnMo. 30(:rNi3.37CrNi3. 40CrNiMc). 45CrNiMov.25cr2Ni4w and so on. As the most common high hardenability steel, 40crMnMo has the low temper brittleness and overheat tendence. It’s mainly used to make parts of large section, high strength and high toughness, such as semi-axis of the large heavy truck.

3)      low hardenability steel

This kind of steel is used to make parts of small section and unimportance. Chrome steel has good hardenability and higher tempering resistance than carbon steel. It also has the wide range of quenching temperature, not-easy overheating and low tendence of strain cracking. All these features lead to its widespread use. Manganese steel has the similar roles with chrome steel. The critical cooling velocity of steel is greatly reduced by manganese. In this way, the strength and hardness are both improved. Properties of boron steel is close to 40Cr, because the boron greatly increases the hardenability. The oil quenching critical diameter of the boron steel is 20-30mm. It is used in automobile semiaxis, worm, splined spindle and so on.