Notizie

Qual è il tipo più comune di cuscinetto a sfere?

The short answer: the cuscinetto a sfere per scanalature profonde is the most common type of ball bearing in the world, and by a wide margin. It is the design you will find in electric motors, pumps, fans, gearboxes, household appliances and almost any piece of general machinery. There are several other common types, and knowing which is which matters when you are specifying a replacement.

The seven ball bearing types in general use

Ball bearings are usually grouped into seven families: deep groove ball bearings, angular contact ball bearings, self-aligning ball bearings, thrust ball bearings, four-point contact ball bearings, thin-section bearings and miniature bearings. Only the first three are common in general industrial duty; the rest are for specific applications.

1. Deep groove ball bearings — the default choice

Deep, uninterrupted raceway grooves in both rings let the bearing carry radial load plus axial load in either direction, and the point contact between ball and groove keeps friction low enough for high-speed running. The design is simple, cheap to produce, and interchangeable across makers because it follows ISO boundary dimensions.

Typical duty: electric motors, pumps, fans, conveyors, power tools, automotive ancillaries, domestic appliances. Available open, with steel shields (ZZ) or with rubber seals (2RS). See our deep groove ball bearing range for the 6000, 6200, 6300 and 6400 series we produce.

One correction worth making: a common claim online is that deep groove ball bearings are “for low speed and high load”. That is backwards. They are the high-speed, light-to-moderate load bearing. Where the load is genuinely heavy, a roller bearing is the right answer, not a bigger ball bearing.

2. Angular contact ball bearings — for combined load and stiffness

In an angular contact bearing the line joining the contact points between ball and raceway sits at an angle to the shaft axis, typically 15°, 25° or 40°. That geometry lets the bearing take axial load in one direction together with radial load, and the steeper the angle the greater the thrust capacity. Because they are usually mounted in opposed pairs, they can be preloaded to give a stiff assembly.

Typical duty: machine tool spindles, gearbox shafts, automotive differentials, pumps running at high speed. Not a general-purpose bearing: if you replace a deep groove bearing with an angular contact one without checking the arrangement, the axial location of the shaft changes.

3. Self-aligning ball bearings — where misalignment is unavoidable

Two rows of balls run on a common sphered raceway in the outer ring, so the shaft can deflect slightly relative to the housing without edge-loading the balls. This is the design to reach for when a shaft passes through several supports, or when the housing cannot be machined square to the shaft.

Typical duty: line shafts, ventilation equipment, light conveyor pulleys, textile machinery. Load capacity is modest — for heavy radial load with misalignment, a self-aligning roller bearing is the correct choice instead.

4. Thrust ball bearings

Designed for axial load only, with a shaft washer, a housing washer and a ball set between them. They cannot carry radial load, and they need a minimum axial load to stop the balls skidding. Used in low-speed, high-thrust positions such as crane hooks and vertical shafts.

5. Four-point contact, thin-section and miniature bearings

Four-point contact bearings take axial load in both directions in a single bearing, useful where space allows only one bearing per position. Thin-section bearings use a reduced cross-section for weight and envelope savings in robotics and aerospace. Miniature bearings cover bore sizes below about 10 mm for instruments, medical devices and small motors.

How to tell which one you have

The part number usually gives it away. A 6xxx number is a deep groove ball bearing, 7xxx is angular contact, 3xxx is tapered roller, 2xxx is spherical roller, and the 12xx / 22xx / 13xx / 23xx families are self-aligning. Suffixes then describe the seals, cage and clearance — our Guida ai suffissi dei cuscinetti explains each letter, and what bearing numbers signify covers the numbering system itself.

Choose by load direction, not by habit

If the load is mainly radial and the speed is high, a deep groove ball bearing is almost always right. If the load is heavy and radial, move to a cylindrical or spherical roller bearing. If there is significant thrust in one direction, use an angular contact or tapered roller bearing. Our engineers will confirm the equivalent specification if you send a sample, a part number or a drawing — request a quotation.

Reference

Boundary dimensions for these bearings are standardised in ISO 15 and tolerances in ISO 492. For geometry and load rating detail see the Timken bearings catalogue e Risorse tecniche Timken.