Guide to Matched Angular Contact Ball Bearings

Matched angular contact ball bearings are a type of angular contact ball bearings, which have become a core component of modern mechanical systems by virtue of their high precision, high rigidity and multifunctional load capacity. In the case of angular contact bearings, there is a contact angle between the balls and the raceways, which enables the load to be carried unidirectionally in the axial direction of the shaft. When two or more of these bearings are paired in a specific configuration, angular contact ball bearings can withstand bi-directional axial loads and provide higher load carrying capacity, higher stiffness, and better alignment performance.

As various of industries seek higher performance, faster speeds and less downtime, the use of matched angular contact bearings has increased dramatically in a variety of fields, especially at high speeds, heavy loads and under extreme operating conditions. To help users better understand and use matched angular contact ball bearings, LNB Bearing will introduce matched angular contact bearings meaning, types, models and application scopes and so on, for users' reference and selection.

1. What is a Matched Angular Contact Ball Bearing?

1.1 Matched angular contact ball bearing definition

Matched angular contact ball bearing consists of two or more single-row angular contact ball bearings combined in a specific way, which is mainly used to withstand bi-directional axial loads, radial loads and tilting moments at the same time. The core design is to make up for the fact that single-row bearings can only withstand unidirectional axial forces by means of paired mounting, so as to meet the needs of machinery in complex working conditions.

1.2 Matched angular contact ball bearings structure

(1) Single row angular contact ball bearing

The structure of single row angular contact ball bearings is mainly composed of inner ring, outer ring, ball and cage, the contact angle is usually 15°, 25° or 40°, but usually can only withstand single direction axial load. In practice, often need to two or more single row angular contact ball bearings combined use, in order to simultaneously withstand two-way axial load or larger size of the joint load.

(2) Paired component

The pairing components of matched angular contact ball bearings generally include the center spacing ring or center dividing ring, whose main function is to adjust the total width of the bearing group and set the appropriate preload. In specific designs, the middle parting ring may be equipped with oil filling holes to optimize the lubrication conditions and improve the running performance.

(3) Preload method

The preload of matched angular contact ball bearings usually has rigid preload, elastic preload, adjusting shim method, temperature difference preload, etc. By adjusting the clearance or applying preload, etc., to improve the bearing rigidity, rotational accuracy and prolong the service life.

2. Matched Angular Contact Ball Bearing Types

According to the mounting direction, force characteristics and application requirements, matched angular contact ball bearings mainly have the following three types of matching:

2.1 Back-to-back matching (DB Type)

(1) Structural characteristics:

Two single row angular contact ball bearing outer ring wide end face (back) relative mounting, “O” type arrangement, its contact angle is V-shaped, support span, can well withstand two-way axial load force and a certain amount of anti-tilting moment, axial clearance adjustment is flexible.

The distance between the pressure centers of the two bearings is L=a1+a2 (a is the distance from the pressure center to the end face of the single bearing), and usually the spanning distance coefficient k=1.2∼1.5.

(2) Common applications:

DB Type matched angular contact ball bearings are commonly used in scenarios requiring high rigidity, vibration and moment resistance, such as machine tool spindles, high-speed equipment, precision instruments, gearboxes, rotary tables and metallurgical equipment.

2.2 Face-to-face matching (DF Type)

(1) Structural characteristics:

Two single-row angular contact ball bearings are mounted opposite each other with narrow end faces of outer ring (front face), “X”-type arrangement, contact angle is A-shaped, the overall structure is more compact. DF matched angular contact ball bearings have better adjustment performance, can compensate for the bending deformation of the shaft, and have better adaptability to the thermal expansion of the shaft (allow axial displacement)

Span L=∣a1-a2∣(usually k≈0.5∼0.8), forming a compact support.

(2) Common applications:

DF Type matched angular contact ball bearings carry smaller axial loads, space constraints, and equipment and scenes sensitive to thermal deformation. Such as motors, high temperature centrifugal pumps, compressor crankshafts, automobile wheel hubs, industrial robots, etc.

2.3 Tandem matching (DT Type)

(1) Structural characteristics:

Two single row angular contact ball bearing two bearings wide end towards the same direction configuration (tandem), no relative end face constraints, “T” type arrangement, its to withstand a single axial load force, load capacity combined superposition. DT Type matched angular contact ball bearing can not withstand bi-directional axial force and tilting moment alone, need to another group of bearings reversed configuration to Another set of bearings is required in a reverse configuration to balance the loads.

Span L ≈ 0 (the center of pressure is nearly coincident).

(2) Common applications

Mainly used in the need to withstand one-way large axial force and high-speed rotation occasions, such as precision spindles, high-speed motors, centrifugal compressor rotor, fan spindles, turbo molecular pumps, marine machinery, aviation equipment and so on.

3.  Selection and Mounting Precautions

In order to ensure that the performance of matched angular contact ball bearings can be fully realized, the selection and mounting process is particularly critical.

3.1 Selection suggestions

(1) Load type determines the matching method

In the selection, according to whether there is axial load, load direction is fixed, whether need to withstand tilting moment and other factors, choose the appropriate pairing method (DB, DF, DT) and contact angle. Such as radial + tilting moment is dominant, need to choose DB back-to-back pairing (anti-tilting the strongest); if the axial load in both directions and need to thermally compensate, choose DF face-to-face pairing (to adapt to thermal expansion of the shaft); and oversized unidirectional axial, the DT series pairing (axial bearing capacity superposition).

(2) Select the contact angle according to the load ratio

Generally speaking, when radial load > axial load, choose 25° (AC type) contact angle (general purpose); axial load > radial load, choose 40° (B type) contact angle (thrust enhancement type); and in the high-speed and light-load scenarios, 15° (C type) contact angle (lowest friction loss).

3.2 Mounting Precautions

(1) Clean the bearings before mounting

Before installation, the bearings and cavities need to be cleaned with aviation gasoline, etc., to avoid pitting caused by residual particles; poor mounting surfaces will lead to bearing off-loading and unstable operation, affecting life and precision.

(2) Precise control of preload

When mounting the matched angular contact ball bearings, the preload will increase the friction and temperature rise, reduce the life; preload is too small will affect the rigidity and precision. Should be combined with equipment design and operating conditions selected reasonable preload level.

(3) Prohibit violent installation

When installing, use special tools or press-fit equipment for installation to ensure that the force is applied to the correct ring surface. Strictly prohibit the use of hammering, stamping and other rough means of installation, to avoid bearing deformation or damage to the raceway.

(4) Proper operation debugging and temperature rise check

After installation, no-load test run should be carried out; temperature rise monitoring (the temperature should not be too high); vibration and noise check, etc., to ensure that the bearings are in good condition before putting into formal operation.

4. Matched Angular Contact Ball Bearing Size Chart

Angular contact ball bearings mainly include single row angular contact ball bearings, matched angular contact ball bearings, split angular contact ball bearings, double row angular contact ball bearings and so on. Previously, LNB Bearing has listed the size chart of single row angular contact ball bearings, and in this article, the size chart of matched angular contact ball bearings will be listed for user's reference, and other types of angular contact ball bearings will be continuously updated in the following blogs.

Matched angular contact ball bearings are formed by combining two single row bearings, which can support bi-directional loads and improve rigidity by arranging them back-to-back (DB), face-to-face (DF) or in tandem (DT). They are widely used in applications subject to bi-directional axial loads, such as machine tool spindles, robot joints, gearboxes, turbochargers, metallurgical equipment, precision machinery, etc.

It is worth noting that angular contact ball bearings mounted in pairs need precise adjustment of preload to balance rigidity and temperature rise; in addition, matched angular contact ball bearings need to be produced in the same batch to ensure performance consistency.

4.1 DB - Type Angular Contact Ball Bearing Series (Back-to-Back)

Model	Type	Inner Dimension (mm)	Outer Dimension  (mm)	Width  (mm)
7000	7000CDB; 7000ACDB; 7000BDB	10	26	16
7200	7200CDB; 7200ACDB; 7200BDB	10	30	18
7300	7300CDB; 7300ACDB; 7300BDB	10	35	22
7001	7001CDB; 7001ACDB; 7001BDB	12	28	16
7201	7201CDB; 7201ACDB; 7201BDB	12	32	20
7301	7301CDB; 7301ACDB; 7301BDB	12	37	24
7002	7002CDB; 7002ACDB; 7002BDB	15	32	18
7202	7202CDB; 7202ACDB; 7202BDB	15	35	22
7302	7302CDB; 7302ACDB; 7302BDB	15	42	26
7003	7003CDB; 7003ACDB; 7003BDB	17	35	20
7203	7203CDB; 7203ACDB; 7203BDB	17	40	24
7303	7303CDB; 7303ACDB; 7303BDB	17	47	28
7004	7004CDB; 7004ACDB; 7004BDB	20	42	24
7204	7204CDB; 7204ACDB; 7204BDB	20	47	28
7304	7304CDB; 7304ACDB; 7304BDB	20	52	30
7005	7005CDB; 7005ACDB; 7005BDB	25	47	24
7205	7205CDB; 7205ACDB; 7205BDB	25	52	30
7305	7305CDB; 7305ACDB; 7305BDB	25	62	34
7006	7006CDB; 7006ACDB; 7006BDB	30	55	26
7206	7206CDB; 7206ACDB; 7206BDB	30	62	32
7306	7306CDB; 7306ACDB; 7306BDB	30	72	38
7007	7007CDB; 7007ACDB; 7007BDB	35	62	28
7207	7207CDB; 7207ACDB; 7207BDB	35	72	34
7307	7307CDB; 7307ACDB; 7307BDB	35	80	42
7008	7008CDB; 7008ACDB; 7008BDB	40	68	30
7208	7208CDB; 7208ACDB; 7208BDB	40	80	36
7308	7308CDB; 7308ACDB; 7308BDB	40	90	46
7009	7009CDB; 7009ACDB; 7009BDB	45	75	32
7209	7209CDB; 7209ACDB; 7209BDB	45	85	38
7309	7309CDB; 7309ACDB; 7309BDB	45	100	50
7010	7010CDB; 7010ACDB; 7010BDB	50	80	32
7210	7210CDB; 7210ACDB; 7210BDB	50	90	40
7310	7310CDB; 7310ACDB; 7310BDB	50	110	54
7011	7011CDB; 7011ACDB; 7011BDB	55	90	36
7211	7211CDB; 7211ACDB; 7211BDB	55	100	42
7311	7311CDB; 7311ACDB; 7311BDB	55	120	58
7012	7012CDB; 7012ACDB; 7012BDB	60	95	36
7212	7212CDB; 7212ACDB; 7212BDB	60	110	44
7312	7312CDB; 7312ACDB; 7312BDB	60	130	62
7013	7013CDB; 7013ACDB; 7013BDB	65	100	36
7213	7213CDB; 7213ACDB; 7213BDB	65	120	46
7313	7313CDB; 7313ACDB; 7313BDB	65	140	66
7014	7014CDB; 7014ACDB; 7014BDB	70	110	40
7214	7214CDB; 7214ACDB; 7214BDB	70	125	48
7314	7314CDB; 7314ACDB; 7314BDB	70	150	70
7015	7015CDB; 7015ACDB; 7015BDB	75	115	40
7215	7215CDB; 7215ACDB; 7215BDB	75	130	50
7315	7315CDB; 7315ACDB; 7315BDB	75	160	74
7016	7016CDB; 7016ACDB; 7016BDB	80	125	44
7216	7216CDB; 7216ACDB; 7216BDB	80	140	52
7316	7316CDB; 7316ACDB; 7316BDB	80	170	78
7017	7017CDB; 7017ACDB; 7017BDB	85	130	44
7217	7217CDB; 7217ACDB; 7217BDB	85	150	56
7317	7317CDB; 7317ACDB; 7317BDB	85	180	82
7018	7018CDB; 7018ACDB; 7018BDB	90	140	48
7218	7218CDB; 7218ACDB; 7218BDB	90	160	60
7318	7318CDB; 7318ACDB; 7318BDB	90	190	86
7019	7019CDB; 7019ACDB; 7019BDB	95	145	48
7219	7219CDB; 7219ACDB; 7219BDB	95	170	64
7319	7319CDB; 7319ACDB; 7319BDB	95	200	90
7020	7020CDB; 7020ACDB; 7020BDB	100	150	48
7220	7220CDB; 7220ACDB; 7220BDB	100	180	68
7320	7320CDB; 7320ACDB; 7320BDB	100	215	94
7021	7021CDB; 7021ACDB; 7021BDB	105	160	52
7221	7221CDB; 7221ACDB; 7221BDB	105	190	72
7321	7321CDB; 7321ACDB; 7321BDB	105	225	98
7022	7022CDB; 7022ACDB; 7022BDB	110	170	56
7222	7222CDB; 7222ACDB; 7222BDB	110	200	76
7322	7322CDB; 7322ACDB; 7322BDB	110	240	100
7024	7024CDB; 7024ACDB; 7024BDB	120	180	56
7224	7224CDB; 7224ACDB; 7224BDB	120	215	80
7324	7324CDB; 7324ACDB; 7324BDB	120	260	110

4.2 DF - Type Angular Contact Ball Bearing Series (Face-to Face)

Model	Type	Inner Dimension (mm)	Outer Dimension  (mm)	Width (mm)
7000	7000CDF; 7000ACDF; 7000BDF	10	26	16
7200	7200CDF; 7200ACDF; 7200BDF	10	30	18
7300	7300CDF; 7300ACDF; 7300BDF	10	35	22
7001	7001CDF; 7001ACDF; 7001BDF	12	28	16
7201	7201CDF; 7201ACDF; 7201BDF	12	32	20
7301	7301CDF; 7301ACDF; 7301BDF	12	37	24
7002	7002CDF; 7002ACDF; 7002BDF	15	32	18
7202	7202CDF; 7202ACDF; 7202BDF	15	35	22
7302	7302CDF; 7302ACDF; 7302BDF	15	42	26
7003	7003CDF; 7003ACDF; 7003BDF	17	35	20
7203	7203CDF; 7203ACDF; 7203BDF	17	40	24
7303	7303CDF; 7303ACDF; 7303BDF	17	47	28
7004	7004CDF; 7004ACDF; 7004BDF	20	42	24
7204	7204CDF; 7204ACDF; 7204BDF	20	47	28
7304	7304CDF; 7304ACDF; 7304BDF	20	52	30
7005	7005CDF; 7005ACDF; 7005BDF	25	47	24
7205	7205CDF; 7205ACDF; 7205BDF	25	52	30
7305	7305CDF; 7305ACDF; 7305BDF	25	62	34
7006	7006CDF; 7006ACDF; 7006BDF	30	55	26
7206	7206CDF; 7206ACDF; 7206BDF	30	62	32
7306	7306CDF; 7306ACDF; 7306BDF	30	72	38
7007	7007CDF; 7007ACDF; 7007BDF	35	62	28
7207	7207CDF; 7207ACDF; 7207BDF	35	72	34
7307	7307CDF; 7307ACDF; 7307BDF	35	80	42
7008	7008CDF; 7008ACDF; 7008BDF	40	68	30
7208	7208CDF; 7208ACDF; 7208BDF	40	80	36
7308	7308CDF; 7308ACDF; 7308BDF	40	90	46
7009	7009CDF; 7009ACDF; 7009BDF	45	75	32
7209	7209CDF; 7209ACDF; 7209BDF	45	85	38
7309	7309CDF; 7309ACDF; 7309BDF	45	100	50
7010	7010CDF; 7010ACDF; 7010BDF	50	80	32
7210	7210CDF; 7210ACDF; 7210BDF	50	90	40
7310	7310CDF; 7310ACDF; 7310BDF	50	110	54
7011	7011CDF; 7011ACDF; 7011BDF	55	90	36
7211	7211CDF; 7211ACDF; 7211BDF	55	100	42
7311	7311CDF; 7311ACDF; 7311BDF	55	120	58
7012	7012CDF; 7012ACDF; 7012BDF	60	95	36
7212	7212CDF; 7212ACDF; 7212BDF	60	110	44
7312	7312CDF; 7312ACDF; 7312BDF	60	130	62
7013	7013CDF; 7013ACDF; 7013BDF	65	100	36
7213	7213CDF; 7213ACDF; 7213BDF	65	120	46
7313	7313CDF; 7313ACDF; 7313BDF	65	140	66
7014	7014CDF; 7014ACDF; 7014BDF	70	110	40
7214	7214CDF; 7214ACDF; 7214BDF	70	125	48
7314	7314CDF; 7314ACDF; 7314BDF	70	150	70
7015	7015CDF; 7015ACDF; 7015BDF	75	115	40
7215	7215CDF; 7215ACDF; 7215BDF	75	130	50
7315	7315CDF; 7315ACDF; 7315BDF	75	160	74
7016	7016CDF; 7016ACDF; 7016BDF	80	125	44
7216	7216CDF; 7216ACDF; 7216BDF	80	140	52
7316	7316CDF; 7316ACDF; 7316BDF	80	170	78
7017	7017CDF; 7017ACDF; 7017BDF	85	130	44
7217	7217CDF; 7217ACDF; 7217BDF	85	150	56
7317	7317CDF; 7317ACDF; 7317BDF	85	180	82
7018	7018CDF; 7018ACDF; 7018BDF	90	140	48
7218	7218CDF; 7218ACDF; 7218BDF	90	160	60
7318	7318CDF; 7318ACDF; 7318BDF	90	190	86
7019	7019CDF; 7019ACDF; 7019BDF	95	145	48
7219	7219CDF; 7219ACDF; 7219BDF	95	170	64
7319	7319CDF; 7319ACDF; 7319BDF	95	200	90
7020	7020CDF; 7020ACDF; 7020BDF	100	150	48
7220	7220CDF; 7220ACDF; 7220BDF	100	180	68
7320	7320CDF; 7320ACDF; 7320BDF	100	215	94
7021	7021CDF; 7021ACDF; 7021BDF	105	160	52
7221	7221CDF; 7221ACDF; 7221BDF	105	190	72
7321	7321CDF; 7321ACDF; 7321BDF	105	225	98
7022	7022CDF; 7022ACDF; 7022BDF	110	170	56
7222	7222CDF; 7222ACDF; 7222BDF	110	200	76
7322	7322CDF; 7322ACDF; 7322BDF	110	240	100
7024	7024CDF; 7024ACDF; 7024BDF	120	180	56
7224	7224CDF; 7224ACDF; 7224BDF	120	215	80
7324	7324CDF; 7324ACDF; 7324BDF	120	260	110

4.3 DT - Type Angular Contact Ball Bearing Series (Tandem)

Model	Type	Inner Dimension (mm)	Outer Dimension  (mm)	Width (mm)
7000	7000CDT; 7000ACDT; 7000BDT	10	26	16
7200	7200CDT; 7200ACDT; 7200BDT	10	30	18
7300	7200CDT; 7200ACDT; 7212BDT	10	35	22
7001	7001CDT; 7001ACDT; 7001BDT	12	28	16
7201	7201CDT; 7201ACDT; 7201BDT	12	32	20
7301	7201CDT; 7201ACDT; 7213BDT	12	37	24
7002	7002CDT; 7002ACDT; 7002BDT	15	32	18
7202	7200CDT; 7200ACDT; 7201BDT	15	35	22
7302	7200CDT; 7200ACDT; 7213BDT	15	42	26
7003	7003CDT; 7003ACDT; 7003BDT	17	35	20
7203	7201CDT; 7201ACDT; 7202BDT	17	40	24
7303	7201CDT; 7201ACDT; 7214BDT	17	47	28
7004	7004CDT; 7004ACDT; 7004BDT	20	42	24
7204	7200CDT; 7200ACDT; 7202BDT	20	47	28
7304	7200CDT; 7200ACDT; 7214BDT	20	52	30
7005	7005CDT; 7005ACDT; 7005BDT	25	47	24
7205	7201CDT; 7201ACDT; 7203BDT	25	52	30
7305	7201CDT; 7201ACDT; 7215BDT	25	62	34
7006	7006CDT; 7006ACDT; 7006BDT	30	55	26
7206	7200CDT; 7200ACDT; 7203BDT	30	62	32
7306	7200CDT; 7200ACDT; 7215BDT	30	72	38
7007	7007CDT; 7007ACDT; 7007BDT	35	62	28
7207	7201CDT; 7201ACDT; 7204BDT	35	72	34
7307	7201CDT; 7201ACDT; 7216BDT	35	80	42
7008	7008CDT; 7008ACDT; 7008BDT	40	68	30
7208	7200CDT; 7200ACDT; 7204BDT	40	80	36
7308	7200CDT; 7200ACDT; 7216BDT	40	90	46
7009	7009CDT; 7009ACDT; 7009BDT	45	75	32
7209	7201CDT; 7201ACDT; 7205BDT	45	85	38
7309	7201CDT; 7201ACDT; 7217BDT	45	100	50
7010	7010CDT; 7010ACDT; 7010BDT	50	80	32
7210	7200CDT; 7200ACDT; 7205BDT	50	90	40
7310	7200CDT; 7200ACDT; 7217BDT	50	110	54
7011	7011CDT; 7011ACDT; 7011BDT	55	90	36
7211	7201CDT; 7201ACDT; 7206BDT	55	100	42
7311	7201CDT; 7201ACDT; 7218BDT	55	120	58
7012	7012CDT; 7012ACDT; 7012BDT	60	95	36
7212	7200CDT; 7200ACDT; 7206BDT	60	110	44
7312	7200CDT; 7200ACDT; 7218BDT	60	130	62
7013	7013CDT; 7013ACDT; 7013BDT	65	100	36
7213	7201CDT; 7201ACDT; 7207BDT	65	120	46
7313	7201CDT; 7201ACDT; 7219BDT	65	140	66
7014	7014CDT; 7014ACDT; 7014BDT	70	110	40
7214	7200CDT; 7200ACDT; 7207BDT	70	125	48
7314	7200CDT; 7200ACDT; 7219BDT	70	150	70
7015	7015CDT; 7015ACDT; 7015BDT	75	115	40
7215	7201CDT; 7201ACDT; 7208BDT	75	130	50
7315	7201CDT; 7201ACDT; 7220BDT	75	160	74
7016	7016CDT; 7016ACDT; 7016BDT	80	125	44
7216	7200CDT; 7200ACDT; 7208BDT	80	140	52
7316	7200CDT; 7200ACDT; 7220BDT	80	170	78
7017	7017CDT; 7017ACDT; 7017BDT	85	130	44
7217	7201CDT; 7201ACDT; 7209BDT	85	150	56
7317	7201CDT; 7201ACDT; 7221BDT	85	180	82
7018	7018CDT; 7018ACDT; 7018BDT	90	140	48
7218	7200CDT; 7200ACDT; 7209BDT	90	160	60
7318	7200CDT; 7200ACDT; 7221BDT	90	190	86
7019	7019CDT; 7019ACDT; 7019BDT	95	145	48
7219	7201CDT; 7201ACDT; 7210BDT	95	170	64
7319	7201CDT; 7201ACDT; 7222BDT	95	200	90
7020	7020CDT; 7020ACDT; 7020BDT	100	150	48
7220	7200CDT; 7200ACDT; 7210BDT	100	180	68
7320	7200CDT; 7200ACDT; 7222BDT	100	215	94
7021	7021CDT; 7021ACDT; 7021BDT	105	160	52
7221	7201CDT; 7201ACDT; 7211BDT	105	190	72
7321	7201CDT; 7201ACDT; 7223BDT	105	225	98
7022	7022CDT; 7022ACDT; 7022BDT	110	170	56
7222	7200CDT; 7200ACDT; 7211BDT	110	200	76
7322	7200CDT; 7200ACDT; 7223BDT	110	240	100
7024	7024CDT; 7024ACDT; 7024BDT	120	180	56
7224	7201CDT; 7201ACDT; 7212BDT	120	215	80
7324	7201CDT; 7201ACDT; 7224BDT	120	260	110

LNB bearings provide full-model, high-quality angular contact ball bearings with different precisions (P0-P6), different ABEC tolerances (1-9 grades), different clearances (C2-C4), different materials (steel, ceramic, stainless steel, etc.), different cages (J type, M type, etc.), and different seals (open, metal shield-ZZ; rubber seal-2RS).