2024/10/04

Regarding Bearing Precision and Tolerances

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Table of contents

1. What is a Bearing Tolerance Classes？

2. Which Grade Tolerance is Best for My Application？

1. What is a Bearing Tolerance Classes？

When it comes to bearings, we often hear the term "ABEC rating," which is used to measure the precision of bearings.

The ABEC (Annular Bearing Engineering Committee) rating system was established by the American Bearing Manufacturers Association to standardize the production and evaluation of bearings, making it easier for consumers to understand and compare bearings of different grades. However, the ABEC rating is not universally applicable to all applications, particularly when it comes to electric bicycles.

ABEC Rating Chart

ABEC	ISO 492	DIN 620	JIS
ABEC 1	Class Normal	P0	Class 0
ABEC 3	Class 6	P6	Class 6
ABEC 5	Class 5	P5	Class 5
ABEC 7	Class 4	P4	Class 4
ABEC 9	Class 2	P2	Class 2

※ The International Organization for Standardization (ISO) standard is ISO 492, the German standard is DIN 620, and the Japanese standard is JIS B1514.

⚠️The ABEC rating ranges from ABEC-1 to ABEC-9, with the number inversely proportional to the tolerance level, meaning that higher numbers indicate lower tolerances. Higher ABEC ratings (lower tolerances) offer better precision, which can potentially impact the smoothness and efficiency of equipment operation, but it doesn't necessarily mean that the bearing-installed components will rotate faster.

Didn't solve your issue? We recommend contacting ISK Bearings directly to ensure optimal performance of your equipment.

2. Which Grade Tolerance is Best for My Application？

The following tables list the actual ABEC tolerances per ABMA Standard 20. The tables list tolerances for both inner and outer rings, in both inch and metric units. These tables are useful in determining sizes and tolerance for components, such as shafts and housings. The designer should always do a tolerance stack up study at both maximum and least material conditions when sizing components, particularly when designing for miniature ball bearings.

Quick Overview of Bearing Precision

(1) P0, ABEC-1 Grade Tolerance (ISO Class Normal)

(2) P6, ABEC-3 Grade Tolerance (ISO Class 6)

(3) P5, ABEC-5 Grade Tolerance (ISO Class 5)

(4) P4, ABEC-7 Grade Tolerance (ISO Class 4)

(5) P2, ABEC-9 Grade Tolerance (ISO Class 2)

(1) P0, ABEC-1 Grade Tolerance (ISO Class Normal)

ISK Bearing is of general-purpose, and the tolerance of common bearings of general-purpose (Class 0)is show in table. Please specify in order if customer have any special tolerance requirement.

Inner Ring Of P0, ABEC-1 Grade Tolerance (ISO Class Normal)

d mm		△dmp		Vdp			Vdmp	Kia	△Bs			VBS
				Diameter series					△Bs
				9	0, 1	2,3,4			all	normal	correct
over	incl	high	low	max			max	max	high		low	max
0	2	0	-	10	8	6	6	10	0	-		12
2	10	0	-	10	8	6	6	10	0	-	-	15
10	18	0	-	10	8	6	6	10	0	-	-	20
18	30	0	-	13	10	8	8	13	0	-	-	20
30	50	0	-	15	12	9	9	15	0	-	-	20
50	80	0	-	19	19	11	11	20	0	-	-	25
80	120	0	-	25	25	15	15	25	0	-	-	25

Outer Ring Of P0, ABEC-1 Grade Tolerance (ISO Class Normal)

D mm		△Dmp		Vdp				VDmp	Kea	△Cs △Cis		Vcs Vcis
				Open Bearing			Capped Bearing
				Diameter series
				9	0, 1	2,3,4	2,3,4
over	incl.	high	low	max.				max.	max.	high	low	max.
2.5	6	0	-8	10	8	6	10	6	15	Identical to △Bs and VBs of inner ring of same bearing
6	18	0	-8	10	8	6	10	6	15
18	30	0	-9	12	9	7	12	7	15
30	50	0	-11	14	11	8	16	8	20
50	80	0	-13	16	13	10	20	10	25
80	120	0	-15	19	19	11	26	11	35
120	150	0	-18	23	23	14	30	14	40
150	180	0	-25	31	31	19	38	19	45
180	250	0	-30	38	38	23	-	23	50

The key to determining the bearing tolerance class lies in the specification of the shaft's rotation accuracy at the support point.

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(2) P6, ABEC-3 Grade Tolerance (ISO Class 6)

Inner Ring Of P6, ABEC-3 Grade Tolerance (ISO Class 6)

Bore Diameter (d)				Bore Tolerance (Δdmp)		Radial Runout (Kia)	Width Tolerance (ΔBS)
mm		inch		Bore Tolerance (Δdmp)		Radial Runout (Kia)	all	single bearing	paired bearings
over	incl.	over	incl.	high	low	max.	high	low
0.6	2.5	0.0236	0.0984	0	-7	5	0	-40	-
2.5	10	0.0984	0.3937	0	-7	6	0	-120	-250
10	18	0.3937	0.7087	0	-7	7	0	-120	-250
18	30	0.7087	1.1811	0	-8	8	0	-120	-250
30	50	1.1811	1.9685	0	-10	10	0	-120	-250
50	80	1.9685	3.1496	0	-12	10	0	-150	-380
80	120	3.1496	4.7244	0	-15	13	0	-200	-380
120	180	4.7244	7.0866	0	-18	18	0	-250	-500
180	250	7.0866	9.8425	0	-22	20	0	-300	-500
250	315	9.8425	12.4016	0	-25	25	0	-350	-500
315	400	12.4016	15.7480	0	-30	30	0	-400	-630

Outer Ring Of P6, ABEC-3 Grade Tolerance (ISO Class 6)

Outer Diameter (D)				Outer Dia. Tolerance (Δdmp)		Radial Runout (Kea)	Width Tolerance (ΔBS)
mm		inch		Outer Dia. Tolerance (Δdmp)		Radial Runout (Kea)	all	single bearing	paired bearings
over	incl.	over	incl.	high	low	max.	high	low
2.5	6	0.0984	0.2362	0	-7	8	Identical to Width Tolerance (ΔBS) of Inner Ring of the same Bearing
6	18	0.2362	0.7087	0	-7	8
18	30	0.7087	1.1811	0	-8	9
30	50	1.1811	1.9685	0	-9	10
50	80	1.9685	3.1496	0	-11	13
80	120	3.1496	4.7244	0	-13	18
120	150	4.7244	5.9055	0	-15	20
150	180	5.9055	7.0866	0	-18	23
180	250	7.0866	9.8425	0	-20	25
250	315	9.8425	12.4016	0	-25	30
315	400	12.4016	15.7480	0	-28	35
400	500	15.7480	19.6850	0	-33	40
500	630	19.6850	24.8031	0	-38	50
630	800	24.8031	31.4961	0	-45	60
800	1000	31.4961	39.3701	0	-60	75

The key to determining the bearing tolerance class lies in the specification of the shaft's rotation accuracy at the support point.

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(3) P5, ABEC-5 Grade Tolerance (ISO Class 5)

Inner Ring Of P5, ABEC-5 Grade Tolerance (ISO Class 5)

Bore Diameter (d)				Bore Tolerance (Δdmp)		Radial Runout (Kia)	Width Tolerance (ΔBS)
mm		inch		Bore Tolerance (Δdmp)		Radial Runout (Kia)	all	single bearing	paired bearings
over	incl.	over	incl.	high	low	max.	high	low
0.6	2.5	0.0236	0.0984	0	-5	4	0	-40	-250
2.5	10	0.0984	0.3937	0	-5	4	0	-40	-250
10	18	0.3937	0.7087	0	-5	4	0	-80	-250
18	30	0.7087	1.1811	0	-6	4	0	-120	-250
30	50	1.1811	1.9685	0	-8	5	0	-120	-250
50	80	1.9685	3.1496	0	-9	5	0	-150	-250
80	120	3.1496	4.7244	0	-10	6	0	-200	-380
120	180	4.7244	7.0866	0	-13	8	0	-250	-380
180	250	7.0866	9.8425	0	-15	10	0	-300	-500
250	315	9.8425	12.4016	0	-18	13	0	-350	-500
315	400	12.4016	15.7480	0	-23	15	0	-400	-630

Outer Ring Of P5, ABEC-5 Grade Tolerance (ISO Class 5)

Outer Diameter (D)				Outer Dia. Tolerance (Δdmp)		Radial Runout (Kea)	Width Tolerance (ΔBS)
mm		inch		Outer Dia. Tolerance (Δdmp)		Radial Runout (Kea)	all	single bearing	paired bearings
over	incl.	over	incl.	high	low	max.	high	low
2.5	6	0.0984	0.2362	0	-5	5	Identical to Width Tolerance (ΔBS) of Inner Ring of the same Bearing
6	18	0.2362	0.7087	0	-5	5
18	30	0.7087	1.1811	0	-6	6
30	50	1.1811	1.9685	0	-6	6
50	80	1.9685	3.1496	0	-9	8
80	120	3.1496	4.7244	0	-10	10
120	150	4.7244	5.9055	0	-11	11
150	180	5.9055	7.0866	0	-13	13
180	250	7.0866	9.8425	0	-15	15
250	315	9.8425	12.4016	0	-18	18
315	400	12.4016	15.7480	0	-20	20
400	500	15.7480	19.6850	0	-23	23
500	630	19.6850	24.8031	0	-28	25
630	800	24.8031	31.4961	0	-35	30

The key to determining the bearing tolerance class lies in the specification of the shaft's rotation accuracy at the support point.

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(4) P4, ABEC-7 Grade Tolerance (ISO Class 4)

Inner Ring Of P4, ABEC-7 Grade Tolerance (ISO Class 4)

Bore Diameter (d)				Bore Tolerance (Δdmp)		Radial Runout (Kia)	Width Tolerance (ΔBS)
mm		inch		Bore Tolerance (Δdmp)		Radial Runout (Kia)	all	single bearing	paired bearings
over	incl.	over	incl.	high	low	max.	high	low
0.6	2.5	0.0236	0.0984	0	-4	2.5	0	-40	-250
2.5	10	0.0984	0.3937	0	-4	2.5	0	-40	-250
10	18	0.3937	0.7087	0	-4	2.5	0	-80	-250
18	30	0.7087	1.1811	0	-5	3	0	-120	-250
30	50	1.1811	1.9685	0	-6	4	0	-120	-250
50	80	1.9685	3.1496	0	-7	4	0	-150	-250
80	120	3.1496	4.7244	0	-8	5	0	-200	-380
120	180	4.7244	7.0866	0	-10	6	0	-250	-380
180	250	7.0866	9.8425	0	-12	8	0	-300	-500

Outer Ring Of P4, ABEC-7 Grade Tolerance (ISO Class 4)

Outer Diameter (D)				Outer Dia. Tolerance (Δdmp)		Radial Runout (Kea)	Width Tolerance (ΔBS)
mm		inch		Outer Dia. Tolerance (Δdmp)		Radial Runout (Kea)	all	single bearing	paired bearings
over	incl.	over	incl.	high	low	max.	high	low
2.5	6	0.0984	0.2362	0	-4	3	Identical to Width Tolerance (ΔBS) of Inner Ring of the same Bearing
6	18	0.2362	0.7087	0	-4	3
18	30	0.7087	1.1811	0	-5	4
30	50	1.1811	1.9685	0	-6	5
50	80	1.9685	3.1496	0	-7	5
80	120	3.1496	4.7244	0	-8	6
120	150	4.7244	5.9055	0	-9	7
150	180	5.9055	7.0866	0	-10	8
180	250	7.0866	9.8425	0	-11	10
250	315	9.8425	12.4016	0	-13	11
315	400	12.4016	15.7480	0	-15	13

The key to determining the bearing tolerance class lies in the specification of the shaft's rotation accuracy at the support point.

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(5) P2, ABEC-9 Grade Tolerance (ISO Class 2)

Inner Ring Of P2, ABEC-9 Grade Tolerance (ISO Class 2)

Bore Diameter (d)				Bore Tolerance (Δdmp)		Radial Runout (Kia)	Width Tolerance (ΔBS)
mm		inch		Bore Tolerance (Δdmp)		Radial Runout (Kia)	all	single bearing	paired bearings
over	incl.	over	incl.	high	low	max.	high	low
0.6	2.5	0.0236	0.0984	0	-2.5	1.5	0	-40	-250
2.5	10	0.0984	0.3937	0	-2.5	1.5	0	-40	-250
10	18	0.3937	0.7087	0	-2.5	1.5	0	-80	-250
18	30	0.7087	1.1811	0	-2.5	2.5	0	-120	-250
30	50	1.1811	1.9685	0	-2.5	2.5	0	-120	-250
50	80	1.9685	3.1496	0	-4	2.5	0	-150	-250
80	120	3.1496	4.7244	0	-5	2.5	0	-200	-380
120	150	4.7244	5.9055	0	-7	2.5	0	-250	-380
150	180	5.9055	7.0866	0	-7	5	0	-250	-380
180	250	7.0866	9.8425	0	-8	5	0	-300	-500

Outer Ring Of P2, ABEC-9 Grade Tolerance (ISO Class 2)

Outer Diameter (D)				Outer Dia. Tolerance (Δdmp)		Radial Runout (Kea)	Width Tolerance (ΔBS)
mm		inch		Outer Dia. Tolerance (Δdmp)		Radial Runout (Kea)	all	single bearing	paired bearings
over	incl.	over	incl.	high	low	max.	high	low
2.5	6	0.0984	0.2362	0	-2.5	1.5	Identical to Width Tolerance (ΔBS) of Inner Ring of the same Bearing
6	18	0.2362	0.7087	0	-2.5	1.5
18	30	0.7087	1.1811	0	-4	2.5
30	50	1.1811	1.9685	0	-4	2.5
50	80	1.9685	3.1496	0	-4	4
80	120	3.1496	4.7244	0	-5	5
120	150	4.7244	5.9055	0	-5	5
150	180	5.9055	7.0866	0	-7	5
180	250	7.0866	9.8425	0	-8	7
250	315	9.8425	12.4016	0	-8	7
315	400	12.4016	15.7480	0	-10	8

The key to determining the bearing tolerance class lies in the specification of the shaft's rotation accuracy at the support point.

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Needle Roller Bearing: Types and Catalogs

Needle roller bearings, are a type of rolling bearing characterized by their slender and elongated needle-shaped rollers. Compared to ball bearings, needle roller bearings have a smaller cross-sectional area and volume but possess higher load-carrying capacity. This makes needle roller bearings excel in applications with limited space, particularly in cases of radial space constraints.

2024/11/12

Knowledge

Introduction to Bearings: Basic knowledge

It is commonly referred to as "bearing" in English, while in Taiwan, it is usually called "軸承". The fundamental principle of a bearing involves the placement of rolling elements, such as balls, needles, or rollers, between the inner and outer rings to facilitate smooth rotation of the shaft.

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Knowledge

Types of Bearings

Generally speaking, a reducer bearing is a device used for rotary or linear rotation, while friction and handling motion occurs. In effect, the bearing surface device is capable of rolling, which causes friction between the bearing surface wheel rolls. When this restraining force is also reduced, it is very easy to move in a rotational or linear fashion - increasing speed and efficiency.

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Regarding Bearing Precision and Tolerances

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Needle Roller Bearing: Types and Catalogs

Introduction to Bearings: Basic knowledge

Types of Bearings

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