Practical FAQs
Q1: I was told you can't use just one; you have to "pair" them. Is that true?
Exactly. A single angular contact bearing cannot support a bi-directional axial load-it only handles thrust in one direction. To handle axial forces from both directions (or to achieve high rigidity), they must be installed in pairs: DB (Back-to-Back), DF (Face-to-Face), or DT (Tandem) arrangements. Back-to-back (DB) is most common for machine tool spindles, offering the highest tilting rigidity.
Q2: Why are they the undisputed king of machine tool spindles?
Two words: Speed and Precision. Their design allows for a large number of rolling elements, creating high load-carrying capacity. More importantly, because of the contact angle, they can be precisely preloaded to eliminate internal clearance. This grants extreme rotational precision and high rigidity-critical for the micron-level accuracy required in CNC machining and grinding spindles.
Q3: I've noticed they run hotter than deep groove bearings. Is this normal?
Yes, it is completely normal under preloaded conditions. Preload generates internal friction to eliminate play, which inherently generates heat. This is a controlled parameter. However, if the temperature suddenly spikes, it indicates insufficient lubricant or excessive preload. Proper lubrication selection (high-speed oil-air mist systems) is critical for managing this heat.
Q4: What happens if I install them the wrong way (e.g., reversing the DB/DF arrangement)?
The bearing will be destroyed quickly. If installed backward, the contact angle will force the bearing to try to separate the inner and outer rings under load, rather than clamping them together. This leads to ball skidding, massive axial displacement, catastrophic heat generation, and eventual seizure.
