Engineering Reference

Miniature & Instrument Ball Bearings


The performance of any ball bearing depends on the characteristics of the selected alloys and their heat treatment. Choosing a material with the correct hardness, corrosion resistance, and fatigue life ensures that a bearing will function reliably within the application's operational and environmental parameters.

With its precision miniature & instrument ball bearings, NHBB offers three standard bearing materials, 440C stainless steel, 52100 chrome steel, and DD400 stainless steel, plus two specialty alloys, BG42® and nitrogen-enriched steel. Bearing materials are heat treated in-house to achieve optimum hardness and dimensional stability.

Stainless Steel (AISI 440C) and Chrome Steel (SAE 52100)

440C stainless steel and 52100 chrome steel are the most common materials used in precision miniature and instrument ball bearings. AISI 440C is a hardened stainless steel suitable for any application that requires corrosion resistance at room to mid-hot temperature range. Chrome steel (SAE 52100) is used for specific ball bearing applications where corrosion resistance is not a major concern. 440C is the standard choice for a wide variety of military and commercial applications, as it is the preferred material with the best availability.

Please note: the properties of 440C balls can be enhanced with a titanium carbide coating. Contact NHBB’s Precision Division to learn more.


As an alternative to 440C, NHBB offers DD400, a specialized stainless steel material suitable for applications that require corrosion resistance and smooth operation. However, the applicability of this material is limited because it is imported. Learn more about DD400.

Specialty Alloys

Extreme operating conditions may require the use of more exotic materials, like BG42® or nitrogen-enriched steel, which perform superbly at high speeds and while enduring extreme temperatures, heavy loads, and corrosive conditions. Although cost considerations occasionally override longevity, the expense involved in more frequent bearing replacement often justifies the higher initial costs of specifying longer lasting specialty metals.

Hybrid Ceramic Ball Bearings

Another option for challenging operating conditions are NHBB's hybrid ceramic ball bearings, which consist of steel rings paired with ceramic (silicon nitride) balls. Hybrid bearings are typically used in applications involving ultra-high speeds or requiring high stiffness. Learn more.

Table of Materials

Included in the chart below are the materials available through NHBB's Precision Division. The chart serves as a good starting point for material selection, although a more detailed analysis of the factors involved in a specific application is required before making a final determination. All materials listed here are heat treated to achieve optimum hardness and dimensional stability. Please contact NHBB to receive help with selecting the right material.

MaterialSpecificationContentsMelt MethodAttributesRoom Temperature Hardness (RC)
AISI 440CAMS 56181% C,
17% Cr,
0.5% Mo

Premium quality, 
Low impurity level
Corrosion resistance

58-65 58-62
SAE 52100 AMS 64441% C
1.45% Cr
CEVM* Premium quality
Very low impurity level
DD400 N/A0.7% C,
13% Cr
CEVM* Import material 
Premium quality
Very low impurity level 
N/A** 58-62
BG42® AMS 57491.1% C
14.75% Cr
4% Mo
1.2% V
VIM/VARPremium quality
Low impurity level
Corrosion resistance
High temperature
Nitrogen-enriched steel AMS 58980.3% C
15% Cr
1% Mo
0.4% N 
P-ESRPremium quality
Extreme corrosion
Long life 
N/A** 60-64

*Consumable Electrode Vacuum Melted
**Material is available in rings only
Vacuum induction melted/vacuum arc remelted
Pressure electroslag remelting
BG42® is a registered trademark of Latrobe Specialty Steel Company.