Materials
The performance of precision miniature and instrument ball bearings is largely dependent on the characteristics of alloys and their heat treatment. Choosing a material with the correct values for hardness, corrosion resistance and fatigue life ensures that the bearing will function reliably within the application’s operational and environmental parameters.
NHBB offers three premium bearing materials for its precision miniature & instrument ball bearings, 440C stainless steel, 52100 chrome steel and DD400, a premium grade of stainless steel. These materials are heat treated in-house to achieve optimum hardness and dimensional stability.
Stainless Steel (AISI 440C) and Chrome Steel (SAE 52100)
AISI 440C stainless steel and SAE 52100 chrome steel are the two most common materials used in precision miniature and instrument ball bearings. Stainless steel (AISI 440C) is suitable for applications requiring corrosion resistance at room to mid-hot temperature range. 440C is used in a wide variety of military and commercial applications because it’s the preferred material with the best availability. Chrome steel (SAE 52100) is used for specific ball bearing applications where corrosion resistance is not a major concern.
Did you know that the properties of 440C balls can be enhanced with a titanium carbide coating? Contact NHBB’s Precision Division to learn more.
DD400
DD400 is a specialized stainless steel patented by Minebea Co., Ltd. The material’s microstructure, which is characterized by fine, evenly distributed carbides (under 10 micrometers in size), results in comparable fatigue life, lower noise and vibration levels, and longer wear resistance than 440C. These characteristics make DD400 suitable for medical and dental applications, which require a smooth, quiet rotation along with corrosion resistance. Keep in mind, however, that its applicability is limited because the material is imported.
Learn more about DD400.
Hybrid Ceramic Ball Bearings
For improved performance and increased life, any of the above materials can be paired with ceramic (silicon nitride) balls. NHBB may suggest the use of hybrid ceramic ball bearings in applications involving very high speeds or high stiffness requirements. Learn more.
Chart of Material Types
The following chart outlines the features and relative advantages of the various alloys available for NHBB’s precision miniature and instrument ball bearings. It 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. Please contact NHBB to receive help with selecting the right material.
| MATERIAL | SPECIFICATION | CONTENTS | MELT METHOD | ATTRIBUTES | ROOM TEMP. HARDNESS (Rc) | |
|---|---|---|---|---|---|---|
| Balls | Rings | |||||
| AISI 440C | AMS 5618 | 1% C, 17% Cr, .5%c Mo |
CEVM* | Premium quality Low impurity level |
58-65 | 58-62 |
| SAE 52100 | AMS 6444 | 1% C 1.45% Cr |
CEVM* | Premium quality Very low impurity level |
60-67 | 60-64 |
| DD400 | N/A | 0.7% C, 13% Cr |
CEVM* | Import material Premium quality Very low impurity level |
N/A** | 58-62 |
*Consumable Electrode Vacuum Melted
**DD400 material is available in rings only