1 Complete Model & Code Explanation

Model: WBB1-8705-2Z

Code Definition

WBB1：NMT miniature bearing series identifier

8705：Basic dimension code

2Z：Double non-contact metal shields

Structure：Double metal shields, no rubber contact seals

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

Important reminder: WBB1-8705-2Z is stainless steel miniature bearing with double metal shields, capable of supporting radial loads and moderate bidirectional axial loads. The 2Z metal shields only block dry solid dust. They do NOT resist water, mist, oil mist or liquid penetration and shall not be used under high humidity or splash conditions. Pre-greased for life at factory; shield construction is sealed and prohibits re-lubrication. Rotational resistance increases slightly and limiting speed decreases compared with open-type bearings.

Basic Parameters

Bore d：8 mm

Outer diameter D：17 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 non-contact metal shields

Oil groove：Without oil groove

Outer ring locating feature：No locating groove or shoulder

Cage：Stamped stainless steel cage

Radial internal clearance：CN standard clearance

Material：Stainless steel

Surface coating：Uncoated

Pre-installed lubricant：Long-life grease pre-filled at factory

Relubrication capability：Re-greasing not available

Duplex arrangement：Not supported, single unit operation only

Basic dynamic load rating：0.168 kN

Basic static load rating：0.076 kN

Reference speed：97 000 r/min

Limiting speed：63 000 r/min

Net weight：0.00031 kg

Indicative carbon footprint：0.00066 kg CO₂e

eClass code：23-05-08-01

UNSPSC code：31171504

Series Suffix Comparison

WBB1-8705：Open type, highest speed, no dust protection

WBB1-8705-Z：Single metal shield, one-side dust barrier

WBB1-8705-2Z：Double metal shields (this model), dual-side dust protection, lifetime pre-greased

WBB1-8705-2RS：Double rubber contact seals, dust & mist resistant, lower limiting speed

Steel 8705-2Z：Bearing steel variant, similar load capacity, no anti-rust property

2 Structure & Operating Characteristics

Japan NMT WBB1-8705-2Z is stainless steel miniature deep groove ball bearing from WBB series equipped with double non-contact metal shields, developed for medium-small precision rotary mechanisms. Fully stainless steel construction provides basic corrosion resistance versus bearing steel alternatives, suitable for dry equipment interiors with mild condensation.

Adopts integrated stamped stainless steel cage ensuring stable ball arrangement and suppressing vibration and noise at high speed. Tiny clearance exists between non-contact 2Z shields and rings, bringing limited friction increase to balance dust protection and high-speed capacity. Dry airborne dust can be blocked, but water vapor and oil mist may penetrate through gaps. Long-life grease is permanently sealed inside upon production; shields cannot be removed for re-lubrication. Standard CN radial clearance matches assembly tolerances of most miniature shafts.

The bearing primarily withstands radial loads and tolerates moderate bidirectional axial loads. Continuous exposure to water mist, liquid splash or heavy oil contamination is forbidden; media penetration will degrade grease and trigger corrosion and wear.

3 Core Performance Advantages

1. Standard metric miniature dimension 8×17×5 mm, compatible with shaft systems of numerous compact precision devices.

2. Stainless steel construction with inherent basic rust resistance for slight condensation in clean environments.

3. Double 2Z non-contact metal shields blocking dry dust, lower friction loss than rubber sealed variants.

4. Factory pre-filled grease for maintenance-free lifetime operation; no extra lubrication required after assembly.

5. Stamped stainless steel cage with lightweight stable structure for continuous high-speed operation of miniature bearings.

6. CN standard radial clearance delivers good interchangeability for direct replacement.

7. Ultra-compact outline, ideal for high-speed miniature transmission units with limited installation space.

4 Typical Application Fields

4.1 Precision Small Drive Motors

Miniature vibration motors, fan motors, built-in high-speed instrument motors, drive spindles of portable household appliances.

4.2 Miniature Automation Actuation Parts

Driven wheels for compact linear modules, rotary encoders, spindles of automated test fixtures.

4.3 Laboratory & Optical Equipment

Compact optical fine-tuning assemblies, internal transmission for analytical instruments, precision rotary sensing components.

4.4 Intelligent Consumer Devices

Transmission assemblies for wearable devices, model aircraft spindles, handheld portable high-speed tools.

5 Assembly Specifications & Usage Guidelines

5.1 Assembly Environment & Operation Standards

Assemble in clean surroundings to avoid coarse dust adhering to bearing surfaces. Never strike bearing end faces or shield areas directly. Use fitting sleeves for uniform pressing to prevent shield deformation or detachment. Strictly control interference fit between shaft and housing. Excessive interference reduces internal clearance and leads to temperature rise and grease deterioration at high speed. Handle miniature bearings carefully to avoid shield denting caused by impact.

5.2 Selection Guidance

Fully enclosed dust-free housing, maximum speed priority → WBB1-8705 open type

Dry atmosphere with floating dust, basic dust protection & maintenance-free demand → WBB1-8705-2Z (this model)

Dust risk on single side and limited installation space → WBB1-8705-Z single shield variant

Exposed to vapor, oil mist or liquid splash requiring penetration resistance → WBB1-8705-2RS rubber sealed version

Dry indoor condition without anti-rust requirement, cost optimization → bearing steel 8705-2Z

5.3 Lubrication Instruction

Special long-life grease is hermetically pre-filled inside the bearing, supporting maintenance-free service under normal working conditions. Shields are non-detachable, on-site re-greasing is impossible. Long-term high temperature or operation over limiting speed accelerates grease aging and shortens service life. Do not soak bearings in solvents; solvent will dissolve internal grease and cause immediate failure.

5.4 Environmental Application Notes

2Z metal shields only defend dry dust, they cannot resist water, mist, liquid or oil vapor ingress. Choose 2RS rubber sealed type for high humidity, mist or oily environments. Stainless steel only offers basic rust resistance; oxidation may still occur under prolonged humid conditions.

6 Daily Maintenance & Fault Troubleshooting

Perform short low-speed running-in after assembly, gradually raise to rated speed only without abnormal noise and excessive temperature rise. Typical faults of 2Z sealed miniature bearings: gradually increasing noise, sluggish rotation, sustained overheating.

Common failure causes: grease deterioration due to vapor/oil mist intrusion, continuous overspeed operation, insufficient clearance from improper mounting, persistent excessive axial load. Once lubrication fails or raceway corrosion and wear occur, repair is impossible; immediate replacement is recommended.