FB204 (UCFB204) 3-Bolt Diamond Flange Mounted Bearing Unit: Structure, Parameters, Advantages & Application Guide

FB204 (UCFB204) 3-Bolt Diamond Flange Mounted Bearing Unit: Structure, Parameters, Advantages & Application Guide

FB204 (complete model UCFB204) is a widely used mounted spherical bearing unit in light automation, conveying machinery, agricultural equipment and food processing machines. Featuring compact size, simple installation, self-aligning performance and convenient maintenance, it is the preferred bearing solution for side-wall mounting and limited-space transmission applications.

Commonly referred to as FB204 in daily communication, the full assembly UCFB204 consists of an FB204 cast iron housing plus a UC204 insert bearing.

1. Definition & Structural Features

FB204 is a 3-bolt diamond flange mounted bearing manufactured to JIS industrial standards. It is pre-assembled and ready for direct installation. Different from pillow block bearings or round flange housings, its unique 3-bolt diamond layout is specially designed for side panel mounting and confined installation spaces.

The whole assembly contains two main parts:

1. Bearing Housing: High-strength HT200 cast iron with good rigidity and deformation resistance. The white anti-corrosion coated version suits humid and clean working environments.
2. Insert Bearing: GCr15 bearing steel with double-sided seals, pre-filled with high-quality grease for wear and temperature resistance.

It adopts set-screw locking on the inner ring to firmly fix the shaft and prevent slipping during forward and reverse rotation. A grease nipple is reserved for re-lubrication to extend service life.

2. Core Technical Specifications

As a standard 20mm bore bearing, FB204 / UCFB204 has fully interchangeable specifications from different manufacturers:

• Bore diameter: 20 mm
• Bearing outer diameter: 47 mm
• Inner ring width: 31 mm
• Mounting flange: Diamond shape with 3 mounting holes, hole diameter Φ8
• Basic dynamic load rating C: 12.7 kN
• Basic static load rating C₀: 6.7 kN
• Limiting speed (grease lubrication): 6500 r/min
• Net weight per unit: approx. 0.55 kg
• Self-aligning capacity: ±2.5°, compensates minor shaft misalignment caused by machining or assembly errors

3. Main Advantages

3.1 Simple installation for side mounting

The 3-hole diamond flange can be bolted directly onto equipment side frames without extra brackets. It greatly shortens assembly time and is ideal for wall-mounted transmission structures.

3.2 Self-aligning design with high tolerance

The spherical outer ring matches the housing bore, offering excellent self-aligning performance. It compensates slight shaft offset and frame deformation, avoiding bearing seizure, abnormal noise and premature wear, and lowering equipment commissioning difficulty.

3.3 Double seals for dust & moisture protection

Double rubber sealing prevents dust, water and debris from entering the bearing cavity. The white coated variant provides superior rust resistance for humid and clean workshops such as food processing lines.

3.4 Flexible maintenance: pre-greased & re-lubricatable

Pre-packed with grease at factory for immediate use with short-term maintenance-free operation. The built-in grease nipple allows periodic re-lubrication for continuously running equipment to reduce breakdown risk.

3.5 High rigidity, stable operation & universal interchangeability

Cast iron housing resists vibration and deformation for smooth quiet running. This standard model is fully interchangeable across manufacturers, which simplifies purchasing, replacement and field repair.

4. Industries & Typical Applications

FB204 is designed for compact side installation, stable transmission and low failure rate. It is widely used in medium & small machinery:

1. Conveying equipment: Belt conveyors, roller lines, chain conveyors, food processing transport lines
2. Agricultural machinery: Grain processing equipment, small harvesters, agricultural transmission assemblies
3. Light industry machinery: Packaging machines, textile equipment, printing machines, automatic production lines
4. General machinery: Small fans, cooling equipment, parking systems and general transmission frames
5. Food machinery: White anti-corrosion coated version for clean and humid food workshops

5. Notes for Selection & Operation

1. FB204 usually refers to the full UCFB204 bearing assembly in trade. FB204 housing alone is without insert bearing, please clarify during purchasing.
2. Regular black cast iron housing is for general industrial use; white coated housing is for anti-rust and food-grade clean applications.
3. The bearing absorbs minor misalignment, but large eccentric installation should be avoided.
4. For continuous medium-high speed running equipment, regular re-greasing is recommended to prevent dry wear.

Summary

FB204 (UCFB204) 3-bolt diamond flange mounted bearing is a classic standard bearing unit with high universality, easy installation and low maintenance cost. Its unique diamond 3-hole side mounting structure solves the installation challenge for side transmission in narrow spaces. With reliable comprehensive performance, it is a cost-effective, widely adopted component for most small and medium automation and light industrial machinery.