Lubrication

Operational conditions such as temperature, loads, speed, torque, and environment determine the lube appropriate for the application. Oils are used where low bearing friction torque is a primary consideration. Grease may provide longer operating life and resist lubricant loss due to centrifugal forces at higher speeds. Dry film lubricants are often appropriate for vacuum environments or other conditions where wet lube is not an option.

Standard vs. custom

Bearing and drive ring designs can be fully customized. Custom units can include simple flanges, intricate lubrication grooves, and O-ring housings or new materials and designs. Technical contacts at the manufacturer can often assist with designing these bearings. For example, if extreme fits are unsuitable, selective assembly of coded bores — matched with similarly graded shaft and housing diameters — may be utilized. This approach is usually more economical than a reduction in diameter tolerances.

Bearings are typically manufactured to standard grades of precision with well-established tolerances for size and geometric accuracy. These standards are known as ABEC classes. They're set by the Annular Bearing Engineers Committee (ABEC) of the American Bearing Manufacturer's Association (ABMA). These standards are also accepted by the American National Standards Institute (ANSI) and by international agreement for those developed by the International Organization of Standards.

Beyond the standard ABEC tolerance — which describes many ball bearing attributes — the bore of the inner ring and the outer ring's outer diameter can be coded to specific requirements. This helps maintain a constant line-to-line fit. Miniature and instrument ball bearings inner and outer diameters can be further calibrated to very specific ranges by designating their applicable dimensional codes.

Installation is as important as bearing design and cleanliness. During installation, at no time can any forces be transmitted from one bearing ring to the other through the balls. This can cause brinneling of the bearing balls, which can result in bearing vibration, noise, and reduced life. Some tips:

1. Force should only be applied to the ring that is being mounted. When installing a bearing on a tight shaft, force is to be applied to the inner ring only.

2. When installing a bearing in a tight housing, force should be applied to the outer ring only.

3. Bearing, tooling, and mounting surfaces should be kept clean and free of all contamination.

4. Mount bearings squarely onto shafts or into housings.

5. Do not apply any shock or impact techniques (like hammering) to install bearings. Also, use proper tooling so as not to damage the bearing or assembly.

6. If uncertain about any ball bearing attributes, consult the bearing manufacturer.

Pacamor Kubar Bearings has been a domestic manufacturer of bearings for over 40 years. For more information, visit pacamor.com or e-mail the editor at eeitel@penton.com.