Spindle bearings are single row angular contact ball bearings, comprising solid inner and outer rings and ball and cage assemblies with solid window cages. They cannot be dismantled. The bearings are available in open and sealed designs.

Spindle bearings have restricted tolerances. They are particularly suitable for bearing arrangements with very high requirements for guidance accuracy and high speeds. They have proved extremely suitable for main spindle bearing arrangements in machine tools.

A detailed description of spindle bearings (designs, calculation, lubrication, speeds, fits) is given in Catalogue AC 41 130, Super Precision Bearings.

The bearings can support axial forces in one direction as well as radial forces. Spindle bearings used in an O or X arrangement can support axial forces in both directions and moments. Bearings in a tandem arrangement can only support axial loads in one direction.

Spindle bearings are available with a contact angle α = 15° (suffix C) or α = 25° (suffix E).

Standard spindle bearings B70, B719 and B72 have steel balls.

Spindle bearings HCB70, HCB719 and HCB72 have balls in standard sizes made from ceramic (hybrid bearings).

Spindle bearings B70..-2RSD, B719..-2RSD, B72..-2RSD, HCB70..-2RSD, HCB719..-2RSD and HCB72..-2RSD are sealed on both sides by gap seals.

Sealed bearings are greased with an FAG high performance grease and are maintenance-free.

High speed spindle bearings HSS70 and HSS719 have smaller steel balls.

In addition, high speed spindle bearings HCS70 and HCS719 with ceramic balls (hybrid bearings) are available.

These four series thus achieve higher speeds, have lower friction and heat generation, place less strain on the lubricant and have a longer operating life.

The bearings are sealed on both sides by gap seals.

Open bearings of series HS70 and HS719 as well as HC70 and HC719 are also available.

Sealed bearings are greased with an FAG high performance grease and are maintenance-free.

X-life ultra bearings have bearing rings made from a nitrogen-containing, corrosion-resistant steel with a particularly fine structure (prefix X) and ceramic balls. They fulfil very high requirements for speed and load carrying capacity. The bearings have longer life compared to conventional bearings. Most series of spindle bearings are available as X-life ultra bearings.

Where the limits of grease lubrication are reached, the spindle bearing range is supplemented by Direct Lube bearings (DLR). They ensure reliable supply of lubricant direct to the contact point via a circumferential annular slot and radial feed holes. DLR bearings can achieve extremely high speeds. They allow economical bearing soloutions since the adjacent construction of the bearing can be of a simpler design.

Spindle bearings of universal design can be fitted in any arrangement or combined in various sets without any loss of performance. The position of the pressure cone is marked on the cylindrical surface of the outer ring.

Bearings with the suffix UL are designed for slight preload in an X or O arrangement.

The preload is altered by mounting and the operating conditions.

When ordering, the number of individual bearings must be stated.

The bearings are suitable for operating temperatures from –30 °C to +100 °C, restricted by the seal or cage material.

The standard grease for sealed spindle bearings is suitable up to a continuous temperature of +80 °C.

The operating temperature must be taken into consideration when selecting the lubricant.

Spindle bearings have solid window cages made from hard fabric (suffix T). The cage is guided on the outer ring.

Check the chemical resistance of the seal or cage material to synthetic greases and lubricants with EP additives.

Aged oil and additives in the oil can impair the operating life of the cages and seals at high temperatures.

The oil change intervals must be observed.

Suffixes for available designs: see table.