68 Series Metric Miniature Ball Bearings for Precision Applications

68 Series

The 68 series metric miniature deep groove ball bearings are a type of compact bearings mainly used in applications where space is limited but high precision and high speed are required. They have a single-row design with a small range of inner diameters, making them suitable for small machinery. Due to the use of high-quality materials and precision machining processes, 68 series bearings are able to provide low friction and high stability at high rotational speeds, with good durability and wear resistance. Common applications include micromotors, precision instruments, medical equipment, and office automation equipment. This series of bearings usually adopts open or sealed design to meet the lubrication and dust-proof requirements under different working conditions.

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68 Series Metric Miniature Ball Bearings - Precision for Confined Spaces

The 68 Series Metric Miniature Ball Bearings are engineered for applications requiring high rotational accuracy within limited spatial constraints. This series is characterized by its compact design and high-precision performance, making it a critical component for modern, miniaturized mechanical systems.

Product Features

Low Cross-Section: The thin-walled design of the 68 series bearings reduces both weight and space requirements, enabling integration into compact assemblies and lightweight equipment. This feature is crucial for industries such as robotics and medical devices.
High Rotational Speed and Low Friction: Manufactured to stringent ISO and DIN standards, these bearings are designed for smooth operation. Their optimized internal geometry minimizes friction, which helps reduce heat generation and prolong component life.
Material Versatility: Available in standard chrome steel (AISI 52100) for general industrial use, and in stainless steel (AISI 440C) for applications in corrosive environments. This material flexibility addresses specific requirements for industries ranging from food processing to aerospace.
Precision Grade: All 68 series bearings are produced to at least ABEC-1 (P0) precision standards, with options for higher grades like ABEC-3 (P6) and ABEC-5 (P5) available for mission-critical applications where high precision is a priority.

Application Areas

The 68 series miniature ball bearings are integral to the performance of various high-precision systems and industrial machinery:

Medical Devices: Used in dental tools, surgical instruments, and lab equipment where size and precision are paramount.
Robotics: Essential for joints and actuators in small-scale robots and robotic arms.
Consumer Electronics: Integrated into small motors and cooling fans for drones and computer hardware.
Instrumentation: Critical for gyroscopes, encoders, and other high-precision measurement devices.

Common Procurement Inquiries

1. How do 68 series bearings compare to flanged bearings for mounting in a housing?

The 68 series bearings, lacking a flange, require a precise housing bore and a retaining ring or snap ring for axial location. In contrast, flanged ball bearings simplify mounting by providing a locating surface. The choice depends on the assembly design; the 68 series is ideal for designs where space is extremely limited and a separate retaining component is acceptable. For a detailed comparison and recommendation, please consult with our engineering team regarding your specific application and tolerance requirements.

2. What is the expected service life of a 68 series bearing in a high-speed, intermittent-duty cycle?

The service life of a miniature ball bearing is primarily determined by its operational load, rotational speed, and lubrication conditions. For high-speed, intermittent-duty cycles, the limiting factors are often fatigue life and thermal stability. Our 68 series bearings are rated for specific dynamic and static loads to meet ISO standards. To accurately predict the L10 life in your specific operating environment, we recommend a detailed analysis of your duty cycle profile, including peak loads and thermal data. Our application engineers can perform a complimentary bearing life calculation based on your exact operating parameters.

Designation				Principal dimensions（mm）					Basic load ratings(N)		Basic load ratings{kgf}		Speed ratings(rpm)			Abutment and fillet dimensions (mm)						Weight(g)
With shiled	Open type	With seal VV	With seal DD	d	D	B	B1	r(min)	Cr	Cor	Cr	Cor	Grease		Oil	da(min)	db(max)	Da(Max)	Db(min)	ra(max)	rb(max)	Open type	With shiled
With shiled	Open type	With seal VV	With seal DD	d	D	B	B1	r(min)	Cr	Cor	Cr	Cor	ZZ	D·D	Z	da(min)	db(max)	Da(Max)	Db(min)	ra(max)	rb(max)	Open type	With shiled
681	-	-	-	1	3	1	-	0.05	80	23	8	2.5	130000	-	150000	1.4	-	2.6	-	0.05	-	0.03	-
681X	681XZZ	-	-	1.5	4	12	2	0.05	112	33	11	3.5	100000	-	120000	1.9	2.1	3.6	3.6	0.05	0.05	0.07	0.11
682	682ZZ	-	-	2	5	15	23	0.08	169	50	17	5	85000	-	100000	2.6	2.7	4.4	4.2	0.08	0.08	0.12	0.17
682X	682XZZ	-	-	2.5	6	18	2.6	0.08	208	74	21	7.5	71000	-	80000	3.1	3.7	5.4	5.4	0.08	0.08	0.23	0.29
683A	683AZZ	-	-	3	7	2	3	0.1	390	130	40	13	63000	-	75000	3.8	4	6.2	6.4	0.1	0.1	0.32	0.45
684A	684AZZ	-	-	4	9	2.5	4	-0.15	640	225	65	23	53000	-	63000	4.8	5.2	8.2	8.1	0.1	0.1	0.63	1.01
685	685ZZ	-	-	5	11	3	5	0.15	715	281	73	29	45000	-	53000	6.2	6.2	9.8	9.9	0.15	0.15	1.2	1.96
686A	686AZZ	686AVV	686ADD	6	13	3.5	5	0.15	1080	440	110	45	40000	38000	50000	7.2	7.4	11.8	11.7	0.15	0.15	1.91	2.69
687	687ZZ1	687VV	687DD	7	14	3.5	5	0.15	1170	510	120	52	40000	34000	45000	8.2	8.5	12.8	12.7	0.15	0.15	2.13	2.97
688A	688AZZ1	688AVV	688ADD	8	16	4	5	0.2	1610	710	164	73	36000	28000	43000	9.6	10.2	14.4	14.2	0.2	0.2	3.12	4.02
689	689ZZ1	689VV	689DD	9	17	4	5	0.2	1330	665	136	68	36000	24000	43000	10.6	11.5	15.4	15.2	0.2	0.2	3.53	4.43