1 Complete Model & Code Explanation

Model：628/6-2Z

Code Definition

628/6：Dimension specification code for non-standard miniature deep groove ball bearing

2Z：Double-side non-contact steel shield with simple dustproof protection

Structure：Closed construction fitted with steel shields on both sides

Supply form：Single independent bearing, no factory duplex grinding, DB/DF duplex arrangement not supported

Important reminder: 628/6-2Z is miniature bearing made of bearing steel with 2Z steel shields. Non-contact shields have lower friction and higher limiting speed compared with equivalent 2RS1 rubber sealed bearings. Steel shields only block dry solid dust and cannot resist mist, steam or liquid splash. Continuous high humidity or splash-prone working conditions are not recommended. Shields cannot be pried open forcibly; deformation leads to permanent loss of dust protection. Bearing steel has no inherent rust resistance, so moisture protection of the whole equipment is required in humid environments to avoid internal corrosion.

Basic Parameters

Bore d：6 mm

Outer diameter D：16 mm

Width B：6 mm

Bearing type：Single-row deep groove ball bearing

Number of rows：Single row

Bore form：Straight cylindrical bore

Seal arrangement：2Z, double-side non-contact steel shield

Cage：Stamped cold rolled steel cage

Material：High carbon chromium bearing steel

Surface coating：Uncoated

Pre-installed lubricant：General long-service grease

Relubrication capability：On-site re-greasing unavailable

Radial internal clearance：Normal clearance class

Duplex arrangement：Not supported, single unit operation only

Basic dynamic load rating：0.066 kN

Basic static load rating：0.025 kN

Reference speed：64 000 r/min

Limiting speed：45 000 r/min

Net weight：0.00027 kg

Indicative carbon footprint：0.00058 kg CO₂e

eClass code：23-05-08-01

UNSPSC code：31171504

Series Suffix Comparison

628/6：Open miniature bearing without shield

628/6-2Z：Double steel shield, high speed dustproof (this model)

628/6-2RS1：Double contact rubber seal, dust & mist resistance, relatively lower speed

628/6-2RS1/VT378：Rubber sealed version filled with food-contact grease

2 Structure & Operating Characteristics

Japan NMT 628/6-2Z adopts bearing steel substrate and double-side non-contact 2Z steel shields. Tiny clearance exists between shields and inner ring without physical contact, delivering low friction loss and stable long-term high-speed operation. Bearing steel features high hardness and load capacity, higher rigidity than stainless steel bearings. It mainly bears radial loads and withstands small bidirectional axial loads.

Without rubber sealing components, risks of rubber aging and swelling failure under transient high temperature are eliminated. However, clearance allows gradual moisture penetration under long-term high humidity, leading to grease emulsification and rolling element rust. Continuous service is only suggested in dry and slightly dusty environments.

3 Core Performance Advantages

1. High carbon chromium bearing steel substrate with high hardness and sufficient rigidity, superior load capacity to same-size stainless steel miniature bearings.

2. Double-side 2Z non-contact steel shields reduce rotational friction, supporting higher limiting speed than equivalent rubber sealed bearings.

3. Free of rubber parts, eliminating rubber aging failure and improving tolerance to short-time elevated temperature.

4. Compact universal dimensions, widely compatible with various small lightweight high-speed transmission mechanisms.

5. Factory pre-filled long-life grease enables long-term maintenance-free service under clean and dry conditions.

6. Symmetrical shielding structure without assembly orientation restriction, suitable for automatic assembly production lines.

4 Typical Application Fields

4.1 Micro Drive Motors

Rotary shafts of small high-speed brushless micro motors and fan motors.

4.2 Imaging & Model Equipment

Shafts for aerial gimbals, drive wheels of RC models, damping structures for compact anti-shake gimbals.

4.3 Office Automation Equipment

Guide rollers inside printers, scanners and compact copiers.

4.4 Small Equipment for Dry Environment

Mini handheld power tools, laboratory test tooling under dry conditions, compact precision sensing devices.

5 Assembly Specifications & Usage Guidelines

5.1 Assembly Environment & Operation Standards

Maintain clean and dry assembly area to reduce suspended dust. Press force shall only act on ring end faces. Knocking or squeezing steel shields is forbidden to avoid deformation and enlarged clearance. Scratches and impacts must be prevented as they easily form corrosion initiation points on bearing steel. Symmetrical shielding design requires no specific installation direction. Never pry shields open for cleaning.

5.2 Selection Guidance

Dry environment, high speed priority, only dry dust present → 628/6-2Z (this model)

Mist and intermittent liquid splash exist, enhanced sealing required → 628/6-2RS1

Food contact application needed → 628/6-2RS1/VT378

Long-term high humidity, frequent condensation or water spray → This model not recommended, select stainless steel sealed bearing

5.3 Lubrication Instruction

Pre-filled with general long-service grease at factory for long-term maintenance-free service under dry and clean conditions. 2Z shields provide basic protection only. Forcible shield dismantling and solvent cleaning are strictly prohibited; protective function cannot be restored once shields deform. Extended continuous high temperature accelerates grease oxidation and drying and shortens service life.

5.4 Environmental Application Notes

2Z non-contact steel shields only block dry solid dust and cannot resist mist, steam or liquid splash. Bearing steel has weak rust resistance; complete equipment sealing and moisture protection are mandatory to stop moisture ingress and corrosion. Not applicable to workstations with frequent condensation or dense mist.

6 Daily Maintenance & Fault Troubleshooting

Conduct low-speed running-in after assembly, confirm no abnormal noise and temperature rise before gradually reaching rated operating speed. Common faults: abnormal noise during high-speed rotation, rotational seizure, sustained temperature rise, internal rust and jamming.

Typical failure causes: continuous dust penetration through shield gaps; prolonged overspeed operation; rust of rolling elements caused by moisture ingress in humid environment; shield deformation from assembly extrusion. Bearings with rust, persistent noise or rotational jam cannot be repaired and replacement is recommended.