nhbb :: hitech engineering

materials

The choice of materials in the design of ball and roller bearings is critical. The proper choice of materials will maximize fatigue life, and specify corrosion resistance and operating temperature limits in addition to establishing speed properties. All environmental conditions must be considered and evaluated in order to make the correct material decisions.

NHBB maintains exacting metallurgical control of all materials from the originating mill through tightly controlled heat treatment and all manufacturing processes.

Ring and Rolling Element Standard and Special Materials

The traditional materials used in rolling element bearings are 52100 chrome steel, 440C stainless steel, and M-50 tool steel. These materials are heat treated to achieve optimum hardness and dimensional stability, and are suitable for most conditions.

For unique and extreme applications, NHBB has the capability of processing many special materials. Hybrid ball bearings, consisting of steel rings and silicon nitride balls, are being used in applications involving ultra high speeds or high stiffness requirements. Cobalt-based alloys possess good oxidation resistance and hot hardness. High speed steels provide somewhat higher hot hardness than M-50. 440C Modified stainless steel can be used in high temperature applications where corrosion resistance is desired. The properties of base bearing materials can be enhanced by coatings such as thin dense chromium or titanium carbide and other surface applications.

	MATERIAL PROPERTIES			HEAT TREATMENT PROPERTIES
Material	Specification	Melt Method	Attributes	Room Temp. Hardness (R_c)	Operating Temp. Limit (°F)‡	Heat Treatment Attributes
52100	AMS 6440	Vacuum Degassed	Available in Tube Form.	60-64	300	Good Wear & Fatigue Properties.
52100	AMS 6444	CEVM*	Premium Quality. Very Low Impurity Level.	58-62	400	Improved Thermal Stability.
440C	AMS 5880	Air Melt or Vacuum Degassed	Corrosion Resistance.	58-62	250	Good Wear Properties.
440C	AMS 5618	CEVM*	Premium Quality with Low Impurity Level.	56-60	600	Thermal Stability with Corrosion Resistance.
M-50	AMS 6491	VIM/VAR**	Premium Quality High Temperature Capabilities.	60-64	800	Excellent Fatigue Properties. High Thermal Stability.
440C Modified	AMS 5749	VIM/VAR**	Premium Quality. Corrosion Resistance. High Temperature Capabilties.	61-65	900	Excellent Wear Properties. High Thermal Stability.
Cobalt-based Alloys	AMS 5759	CEVM*	Chemical Resistance. High Temperature Capabilities.	50 min.	1600	Good Thermal Stability. Low Hardness Reduction at Elevated Temperature.

* Consumable Electrode Vacuum Melted
**Vacuum Induction Melted/Vacuum Arc Remelted
‡Consult NHBB Engineering for higher operating temperature requirements.