1 Complete Model & Code Explanation

Model：W 625-2Z/VT378

Code Definition

W：Stainless steel series with basic rust and mild corrosion resistance

625：Basic outer dimension of miniature deep groove ball bearing

2Z：Double-side pressed steel non-contact shield

VT378：Grade of pre-filled food-contact lubricating grease

Structure：Closed construction with riveted steel shields on both ends

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

Important reminder: W 625-2Z/VT378 is stainless steel miniature bearing. Compared with bearing steel bearings, it features improved anti-rust performance suitable for humid and mild corrosive conditions, while its basic load capacity is slightly lower. 2Z steel shields adopt clearance non-contact structure with low running resistance. It only blocks coarse dry dust, unable to prevent continuous water splash, mist and fine dust penetration. Steel shields are permanently riveted and non-detachable; cleaning and on-site re-lubrication are prohibited. Internal VT378 grease is specially selected for food-contact applications and must not be arbitrarily replaced with other lubricants.

Basic Parameters

Bore d：5 mm

Outer diameter D：16 mm

Width B：5 mm

Bearing type：Single-row deep groove ball bearing

Number of rows：Single row

Bore form：Straight cylindrical bore

Seal arrangement：2Z double pressed steel non-contact shield

Cage：Stamped stainless steel cage

Material：Stainless steel

Surface coating：Uncoated

Pre-installed lubricant：VT378 food-contact 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：0.072 kN

Basic static load rating：0.029 kN

Reference speed：72 000 r/min

Limiting speed：48 000 r/min

Net weight：0.00024 kg

Indicative carbon footprint：0.00058 kg CO₂e

eClass code：23-05-08-01

UNSPSC code：31171504

Series Suffix Comparison

625-2Z/C3：Bearing steel, standard grease, C3 clearance

W 625-2Z：Stainless steel, double steel shield, standard grease, normal clearance

W 625-2Z/VT378：Stainless steel, 2Z shield, VT378 food-grade grease (this model)

W 625-2RS/VT378：Stainless steel rubber seal, VT378 grease, superior dust & mist resistance, lower speed

W 625：Open type stainless steel bearing without protection

2 Structure & Operating Characteristics

Japan NMT W 625-2Z/VT378 adopts standard 625 dimension platform, fully manufactured from stainless steel, equipped with double-side 2Z pressed steel shields and VT378 food-compliant grease, developed for humid environments and light-duty food light-industry equipment. Stainless steel material resists moisture, condensation and mild weak acid & alkali mist, greatly reducing rust risk.

A tiny clearance exists between steel shields and inner ring without contact friction to sustain relatively high rotating speed. Nevertheless, clearance structure provides limited protection; foreign matter will invade under long-term mist or liquid splash. Standard radial clearance is matched for assembly within conventional temperature range. Continuous high-temperature operation is not recommended to avoid premature aging of VT378 grease. Stamped stainless steel cage delivers improved corrosion resistance for light rotary components exposed to intermittent moisture. The bearing mainly withstands radial loads and bears moderate bidirectional axial loads. Long-term overspeed operation is prohibited.

3 Core Performance Advantages

1. Integrated W-series stainless steel construction achieves excellent rust resistance over bearing steel bearings, tolerating condensed moisture and mildly corrosive atmosphere.

2. Pre-filled VT378 food-contact certified grease, meeting sanitary matching requirements of food, beverage and packaging machinery.

3. Double-side 2Z steel non-contact shields reduce friction loss; limiting speed is higher than same-size stainless steel bearings with rubber seals.

4. Symmetrical shielding structure on both ends with no assembly orientation required, simplifying automatic production line assembly.

5. Standard 625 outer dimension supports direct same-size interchangeability, convenient for upgrading existing bearing steel equipment.

6. All-metal design without rubber components, eliminating risks of rubber swelling and aging, suitable for intermittent contact with some food detergents.

4 Typical Application Fields

4.1 Light-Duty Food & Beverage Equipment

Small food conveyor rollers, auxiliary guide rollers for bottled beverage lines, light rotary shafts for snack processing.

4.2 Packaging Automation Machinery

Micro rotary assemblies of small vertical packaging machines, labeler guide rollers.

4.3 Laboratory & Pure Water Instruments

Light transmission mechanisms in pure water equipment, light-duty rotary gimbals for physical and chemical experiments.

4.4 Light-Duty Corrosion-Resistant Devices

Internal micro rotary shafts of humidifying equipment, outdoor light miniature transmission rollers.

5 Assembly Specifications & Usage Guidelines

5.1 Assembly Environment & Operation Standards

Maintain clean and dry assembly area to prevent hard particles entering the bearing. Press force must act only on ring end faces. Knocking or prying steel shields is strictly forbidden to avoid shield deformation and clearance deviation. Stainless steel hardness is lower than bearing steel; avoid surface impact which may form corrosion initiation points. Symmetrical shield structure has no installation direction limitation.

5.2 Selection Guidance

High speed in dry environment, no anti-corrosion demand → Bearing steel 625 series

Humid environment, basic rust protection, standard lubrication → W 625-2Z

Humid clean environment, food-grade lubrication required, coarse dust blocking → W 625-2Z/VT378 (this model)

Long-term mist, intermittent liquid splash, enhanced sealing needed → W 625-2RS/VT378

Continuous immersion in strong acid or alkali → Higher-grade corrosion-resistant bearing solution required

5.3 Lubrication Instruction

Pre-filled with special VT378 food-contact grease complying with food industry sanitary standards, supporting maintenance-free operation under standard conditions. 2Z steel shields are permanently riveted closed. Dismantling shields, solvent cleaning and mixing with other lubricants are strictly prohibited, otherwise food compliance will be invalidated. Continuous high temperature and long-time water spray accelerate grease loss and deterioration, shortening bearing service life.

5.4 Environmental Application Notes

2Z steel shields only block dry coarse solid contaminants, incapable of stopping water mist, fine dust and direct liquid splash. Stainless steel offers basic rust resistance but is not rust-proof under all circumstances; pitting corrosion will occur under prolonged immersion in salt water or strong corrosive media. The built-in grease is specially formulated for food scenarios and cannot be transferred to non-food high-temperature heavy-load applications.

6 Daily Maintenance & Fault Troubleshooting

Conduct low-speed running-in after assembly, confirm no abnormal noise and temperature rise before gradually increasing to rated speed. Common faults: increased rotation resistance, louder operating noise, surface rust spots.

Typical failure causes: continuous mist penetration leading to rolling element rust; grease contamination and deterioration by moisture; surface corrosion origins caused by assembly collision; prolonged operation exceeding limiting speed. Once pitting corrosion or rolling element jamming appears, the bearing cannot be repaired and replacement is recommended.