Guide To Angular Contact Ball Bearing Combinations In Varying ...

The high-performance bearing types are important in machinery. Along with ball bearings, angular contact ball bearings are one of the most commonly and reliably used bearing types in machinery with rolling element bearings. These bearings are beneficial when the load conditions require radial loads with axial loads.

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In the following guide, we will look at the combinations of angular contact ball bearings and their potential applications to assist with selecting the best solution to suit your machinery.

What are Angular Contact Ball Bearings?

Angular contact ball bearings allow you to support radial and axial loads at the same time with more rigidity. An angular contact ball bearing has an inner and outer ring, with a set of balls that are designed at an angle to the bearing axis. The angular design of angular contact ball bearings is useful as it allows companies to support combined loads.

Moreover, they provide higher stiffness, precision, and high speeds. Angular contact ball bearings come in a variety of combinations of single-row, double-row, and paired angular contact, and they have different design features and capabilities depending on the application. 

Key Features of Angular Contact Ball Bearings

Load Carrying Capacity: Angular contact ball bearings allow you to carry radial and axial loads.

Precision and Speed: Angular contact ball bearings are intended to be used in high speeds and low friction.

Low Operating Temperature: Excellent performance at elevated speeds and temperatures.

Axial Load Capabilities: Can support axial loads greater than conventional radial ball bearings.

Angular Contact Ball Bearings Combinations 

1. Single Row Angular Contact Ball Bearings

Single row angular contact ball bearings are the most common type of angular contact ball bearings. They consist of one row of balls supporting radial as well as axial loads but in only one direction. An axial load creates a contact angle that can vary depending on the application.

Applications: Single row angular contact ball bearings are recommended for any application where an axial load is moderate and unidirectional. Examples – electric motors, machine tools, and automobile steering.

2. Paired Angular Contact Ball Bearings

Paired angular contact ball bearings consist of a set of two or more bearings that are assembled in a way that supports axial loads in both directions. The configurations can either be back-to-back (DB), face-to-face (DF), or tandem (DT).

Back-to-Back (DB) Pair

Description: A Back-to-Back (DB) arrangement has the bearings with the contact angles facing away from one another, allowing the system to support axial loads in both directions.

Applications: Common applications include spindles, gearboxes, and machine tool stations where axial load balancing is critical. Back-to-back arrangements of paired angular contact ball bearings usually offer high rigidity and accuracy and can be found in machines like printers and CNC equipment.

Face-to-Face (DF) Pair

Description: An assembly of angular contact bearings in which the contact angles are facing towards each other could be termed a Face-to-Face (DF) arrangement. This allows the assembly to support radial loads while accommodating axial loads in both directions.

Applications: DP is the preferred arrangement in applications where the shaft’s axial displacement should be accommodated while supporting a radial load, e.g., pumps and electric motors. DF is also found in moderate axial load applications that do not require extreme precision, but the axial displacement capability is not an acceptable trade-off.

Tandem (DT) Pair

Description: This set-up consists of bearings with the same contact angle arranged in a series to provide as uniform a load distribution as possible.

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Applications: These are typically found used in high-speed turbines or roller bearings and particularly when one direction of the axial load is more. They can also be found in all applications where ultra-high speeds are requirement such as in sports equipment, cycling hubs, and racing vehicles.

3. Double-Row Angular Contact Ball Bearings

Double-row angular contact ball bearings have two rows of balls arranged in one bearing. double-row angular contact ball bearings can accommodate both radial and axial load,  both directions, and used for higher load capacities than single-row variations.

Applications: Dual-row angular contact ball bearings are used in applications requiring greater load-carrying capacities and requiring both radial and axial loads. Throughout the industry, they are mostly used in automotive wheel hubs, pumps used in motors, and electrical generators.

4. Four-Point Contact Ball Bearings

Four-point contact ball bearings are a type of angular contact ball bearing, capable of supporting both radial and axial loads in either direction. As a one-row bearing with two contact points per ball, a four-point contact ball bearing is a compact solution that aims to support very high loads and radial loads.

Applications: You will find these bearings in applications such as turntable systems, solar tracking systems and very large devices and machines where rotational motion is vital for operational control. They are designed for loads that will apply both axial and radial loads, but in limited radial spaces.

Choosing the Right Forces, Speed, Precision, Space, and Combination in Angular Contact Ball Bearing Applications 

Selecting the correct combination of angular contact ball bearings will require analysis of the application and its requirements, including loading type, speed of operation, precision level, and subsequent axial demands, and of course, any space constraints. The following is a simplified overview to select the proper combination:

Load Type and Direction:  Attain and determine if the axial load is unidirectional or bidirectional. This will dictate if you should have a single-row configuration or paired configuration with the single-row layout, two-rows or combined arrangements.

Speed and Temperature: High-speed applications will require bearings that operate at low friction and temperatures. This can be influenced by the contact angle in conditions of high speed load, as the bearing’s contact angle has to be increased to reach higher speed loads.

Rigidity and Precision: When considering machinery for high precision, typically found in single-direction applications such as NC machines and robotics, the best configuration may be a paired arrangement with back-to-back (DB) to maximize rigidity and stability.

Available Space:  If space is limited then the four-point contact ball bearings or single-row bearings can be the ideal configurations to use. These both are designed to limit space and weight while increasing the performance.

Typical Uses of Angular Contact Ball Bearings

Machine Tools: Angular contact ball bearings are usually found in machine tool spindles, CNC machines, etc. These are used due to their high-speed capabilities and their ability to perform high-speed applications.

Electric Motors: Electric motors need technical bearings capable of radial and axial loading, in high-speed application environments. Single-row and double-row angular contact ball bearings, in general, are typically used in DC motors, AC motors, and Servo motors.

Automotive Industry: In vehicle systems in the automotive world, like wheel hubs and transmissions, an angular contact ball bearing can be used to provide smooth, consistent motion. Double-row angular contact ball bearings are typically used in a vehicle’s wheel hub because they need to be able to withstand significant radial and axial loads.

Aerospace: Angular contact ball bearings are important in the tactical aerospace world. These are commonly used in turbine assemblies, rotors, and in other high-speed components where precision is extremely important, but handling a load is imperative.

Robotics: The use of angular contact ball bearings fashioned into robotic arms allows for very smooth, high-precision movement under the load of the part it is actuating. Today’s advances in robotic arm capabilities help industrial automation become more efficient and effective.

Conclusion

Angular contact ball bearings are important part in any machine that needs to carry axial or radial loads. Whether you are using single-row bearings, double-row bearings, or four-point contact bearings. The right combination is important to maximize the performance and reliability of your machine.

Decent Machinery has a full line of angular contact ball bearings, as per your needs! Our knowledgeable and experienced engineers are available to help assist in finding the right bearings combinations, allowing you to keep your machinery running effectively and efficiently.

If you need professional advice, customized solutions, or want to find out more about angular contact ball bearings, get in touch with Decent Machinery today!

0. to 0.” width variance difference between the inner ring and outer ring is really high, that should be much tighter. What is the full part number of the bearings? Are the bearings mounted face to face, or back to back? If these are universal ground bearings, there should be no preload or end play, it seems like there might be two different grinds getting mixed together.

I purchased a package of five (non matched), AC bearings,

The inner races are wider than the outer races by between 0.” and 0.” :

#1 0.”
#2 0.”
#3 0.”
#4 0.”
#5 0.”

I have installed them DF, (Duplex Front to Front), with a 0.005" shim between them that only touches the outer races. With that shim installed, the outer races should be in full contact, and there should be a small gap about 0.002" between the inner races with no tension on the retaining nut. As I torque the retaining nut, I would expect that 0.002" gap to approach zero. I don't have a sense of how much torque would be required to close that 0.002" gap and provide a bit of preload? I want to make sure I understand this correctly.....

My understanding is that these bearings will either have slightly wider inner races, or slightly wider outer races, and when properly installed the preload force on the bearing will move from the (unloaded distorted shape) to the preloaded non-distorted shape where the inner and outer races of the matched pair will be in full contact and some predetermined preload will exist. If my understanding is correct, that would mean to get the bearings to the preloaded non distorted shape, the clamping force would have to be applied to:
- the outer races if they were narrower than the inner races,
- the inner races if they were narrower than the outer races.

So in a application where the ballscrew retaining nut is applying the clamping force only to the inner race, the bearings would have to have slightly narrower inner races style. If the inner races were actually wider it would not be possible to preload them with the ballscrew retaining nut, because it would simply clamp the already touching inner races while leaving the outer races loose.

Is my understanding correct, or am I missing something? You don’t have a matched pair, so there is not a predetermine preload with the bearings you bought. The bearings you purchased have a width tolerance of each ring of +0, -0.12mm, there is not an assembled tolerance, so it is the luck of the draw on whether the inner or outer ring is wider. When assembling these bearings, you need to have some sort of adjustment to take up the end play, or add preload. These typically are not used as adjacent pairs since you need to make adjustments to get them set right. For an adjacent pair, universally ground, or back to back, or face to face with ground in preload is preferable. You can also get ball screw bearings that have higher axial load ratings than angular contact bearings.

You need a clamping force on both the inner and outer rings. The housing would provide that force on the outer rings by means of a shoulder and bearing cap that presses against the outer ring, and a shoulder on the leadscrew and the locknut does that for the inner rings. The only difference is where the gap is between the rings, that determines whether the housing or the locknut is providing the adjustment. Since you have these arranged face to face, a shim on the shaft would be necessary and the preload force gets applied to the outer rings. If you mount them back to back, the shim would go on the outer rings and the locknut would provide the preload force.

You don’t have a matched pair, so there is not a predetermine preload with the bearings you bought. The bearings you purchased have a width tolerance of each ring of +0, -0.12mm, there is not an assembled tolerance, so it is the luck of the draw on whether the inner or outer ring is wider. When assembling these bearings, you need to have some sort of adjustment to take up the end play, or add preload. These typically are not used as adjacent pairs since you need to make adjustments to get them set right. For an adjacent pair, universally ground, or back to back, or face to face with ground in preload is preferable. You can also get ball screw bearings that have higher axial load ratings than angular contact bearings.

You need a clamping force on both the inner and outer rings. The housing would provide that force on the outer rings by means of a shoulder and bearing cap that presses against the outer ring, and a shoulder on the leadscrew and the locknut does that for the inner rings. The only difference is where the gap is between the rings, that determines whether the housing or the locknut is providing the adjustment. Since you have these arranged face to face, a shim on the shaft would be necessary and the preload force gets applied to the outer rings. If you mount them back to back, the shim would go on the outer rings and the locknut would provide the preload force.

Thanks that makes sense. I found a set of matched NSK C bearings on eBay and ordered them.

With the new set being matched can I simply snug up and lock the ballscrew retaining nut without fear of over preloading them?

One of my buddies suggested, tighten a little and then measure torque required to turn the ballscrew, if less than 5-7 in-lbs, tighten a bit more until 5-7in-lbs is required and then lock it down. Does this seem like a viable approach?

The static load rating of these bearings is N, and according to engineering toolbox, you need only 4Nm (3ft-lbs) to apply N of force so I better go easy. Is that the full bearing part number? If so, they are not matched, and they are not appropriate for a ball screw. The C indicates they have a contact angle of 15 degrees, you want 40 or more. Low contact angles are good for spindles with radial loads, ball screws have very little, if any, radial load, so the higher contact angle is needed for the axial load capacity. Ball screw support bearings have a contact angle of 60 degrees as a comparison. Matched pairs will have a suffix to indicate how they were ground, and need to be installed, if that is lacking, then you need to assume they are not matched. Those bearings might work in your application, but not the best choice.

Download the NSK industrial bearings catalog at this link, page C70 starts the section on angular contact bearings.

Catalogs & CAD Drawings

Explore our complete product lineup of bearings and linear motion products. See our latest publications and technical figures, including CAD data. Keep in mind bearing part numbers are not necessarily the same across manufacturers, so what NSK specifies for a particular bearing can be different for FAG or SKF.

Your friends recommendation is correct, it doesn’t take much torque on the nut to take up the end play and add a bit of preload. Finger torque is usually enough. Static load rating is the maximum safe load before you damage the bearings, you don’t want to be anywhere near that in this application. These are small bearings, so take it slow and only do as much as is needed, and no more.

Instead of randomly buying off of Ebay, you really need to call a local bearing distributor and let them select the bearings you need. The full part # is NSK CTYDULP4 (2 matched bearings in the same box)

Correct these are 15 degrees so not ideal but likely a lot better than what's in there at the moment. In the longer term I might make or purchase larger bearing blocks so I can accommodate larger bearings. The static rating of these bearings is N

I don't have a sense for how many N of force these bearings would be subjected to in actual practice, this is a smaller 8x30knee mill (table weighs perhaps 100lbs) with ac servos directly driving the smallish ballscrews. The servo's can move the table rapidly, however I have limited speed to 100IPM, with acceleration of 4IPS for now, so that only works out to about 5N based on F=ma. That's assuming no friction.

I imagine the cutting forces far exceed what is required to just move the table, I did find a MIT paper that discusses this topic they tested a MUCH larger mill (800kg table) with 3kW servos and maximum force was about N.