Ultra-High Temperatures

In recent years, the operating temperatures of machines have been steadily polarizing between high-temperature and low-temperature. Now we would like to introduce ultra-high-temperature technology.

The Issue

The composition of both metal and plastic is sometimes changed by temperature. In the case of bearing steels (special steels out of which bearings are made), if annealing temperature is exceeded, the structure softens and the life span shortens while size changes. With plastic, adding heat causes melting and the plastic becomes unable to withstand even a slight external force, and high temperatures also cause such phenomena as fusion and carbonization to occur.

With common bearing steels, the limit is said to be approximately 120 degrees Centigrade, and with all-purpose engineering plastics, it is said to be around 100 degrees Centigrade.

Solving the Problem with Supertechnology

■For Metal Materials ...

To curb size changes and softening at high temperatures, we have changed composition and performed special heat processing and surface processing.

One example is the AS (Advanced Super Performance) Bearings Series. This bearing has a complex structure in which the entire rolling surface is covered by metal material for hardness, and to prevent life span shortening due to hard foreign substances getting into the rolling surface, soft sections also left in place while the center is imparted with toughness (a property that prevents cracks and their propagation).

Also, by applying our exclusive treatment to the special stainless steel, we have already made practical bearings that can rotate at the high temperature of 400 degrees Centigrade.

■For Plastics ...

In the case of plastics, the heat-resisting properties of the base material itself are dominant, and we are applying the following techniques to improve the heat resistance:

1. Filler-Based Method

The material is filled with carbon fiber, glass fiber and other fillers. Recently nanosized fillers and the like are also used.

This method is effective for increasing mechanical strength at high temperatures.

2. Method of Increasing Molecular Weight (boosting crosslink density)

This is a method of making the molecules that compose the material form more bonds than usual. With almost no change in specific gravity, heat resistance and other mechanical properties are improved using this method.

3. Other Methods

These are methods that introduce carbon-fluorine bonds, silicon-oxygen bonds and ring structure. At NTN, by combining these techniques, we have succeeded in developing material whose heat resistance exceeds 400 degrees Centigrade.

Supertechnology Products