Materials
The ultimate performance of any ball bearing depends 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 a bearing will function reliably within an application’s operational and environmental parameters.
The most common materials used in precision miniature and instrument ball bearings are 440C stainless steel and 52100 chrome steel. AISI 440C is a hardened, stainless steel suitable for applications which require corrosion resistance at room to mid-hot temperature range. 440C is the standard choice for a wide variety of military and commercial applications, as it is the preferred material with the best availability. The properties of 440C balls can also be enhanced with a titanium carbide coating (limited availability). Chrome steel (SAE 52100) is used for specific ball bearing applications where corrosion resistance is not a major concern.
As an alternative, NHBB offers a specialized stainless steel material, DD400, for its precision miniature and instrument bearings. DD400 is a hardened stainless steel suitable for applications that require corrosion resistance and smooth operation. The applicability of this material is limited, however, due to the fact that it is imported.
For unique or extreme applications, NHBB can also supply hybrid ceramic ball bearings, which consist of steel rings and silicon nitride balls. These are typically used in applications involving ultra-high speeds or high stiffness requirements.
All of the materials utilized by NHBB are heat treated in house to achieve optimum hardness and dimensional stability.
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