The F604ZZ Flange Deep Groove Ball Bearing (4x12x4mm) is a miniature, high-precision radial ball bearing engineered for low-friction rotary motion and accurate axial positioning in compact mechanical assemblies. Featuring an integrated solid outer-ring flange and dual metal dust shields (ZZ), this bearing prevents axial shifting inside housing bores while keeping internal raceways clean from dust and debris, making it an essential component for 3D printer idler pulleys, extruder drive blocks, CNC guide rollers, and precision robotics.

Specification

• Bearing Model: F604ZZ (Flanged Miniature Series)
• Bore Diameter (Inner Diameter / ID): 4.0mm
• Outer Diameter (OD): 12.0mm
• Bearing Width / Thickness (W): 4.0mm
• Flange Diameter (D1): Approx. 13.5mm
• Flange Thickness (C1): Approx. 1.0mm
• Material: High-Grade GCr15 Chrome Bearing Steel (High carbon chromium steel)
• Shielding / Closure Type: Dual Metal Shielded (ZZ - Pressed steel shields on both sides)
• Internal Clearance: Standard Precision Radial Clearance (C0 / ABEC-1 to ABEC-3 standard)
• Lubrication: Pre-lubricated with high-stability micro-bearing grease
• Dynamic Load Rating (Cr): Approx. 960 N
• Static Load Rating (Cor): Approx. 350 N
• Rotational Speed Limit: Up to 34,000 RPM (Grease lubrication)
• Fastener / Shaft Compatibility: Fits standard 4mm precision dowel pins, smooth shafts, and M4 metric shoulder bolts.

Features

• Integrated Outer Flange for Positive Axial Retention: The precision-machined outer ring flange acts as a built-in mechanical stop, seating flush against housing plates or mounting brackets to eliminate axial migration under continuous belt tension.
• Dual Metal Dust Shields (ZZ): Fitted with stamped steel shields on both sides to retain factory lubricant while providing a robust barrier against workshop dust, plastic debris, and fine particles.
• High-Speed & Low-Friction Operation: Precision-ground deep groove raceways and micro-polished steel balls deliver smooth rotation, low rotational torque, and quiet running performance even at high RPMs.
• High Wear & Fatigue Resistance: Heat-treated chromium bearing steel construction provides high hardness, structural rigidity, and resistance to deformation under sustained radial loads.
• Ideal for Dual-Bearing Idler Stacks: Two F604ZZ bearings can be pressed flange-to-flange or placed inside GT2 idler housings to create self-centering, guided belt pulley assemblies without requiring extra retaining rings.

Common Applications

• 3D Printer Timing Belt Idlers & Tensioners: Used in Voron, CoreXY, Creality, and custom RepRap printers as smooth idlers and belt guide rollers for 6mm GT2 timing belts.
• Extruder Filament Drive Assemblies: Serving as the low-friction idler bearing pressing filament against the extruder drive gear in direct-drive and Bowden feeder mechanisms.
• Small CNC Routers & Laser Engravers: Providing smooth, low-friction roller support for lightweight axis drives, limit switch triggers, and motorized slide stages.
• Robotics & Precision RC Models: Guiding miniature drive belts, steering linkages, gearbox output shafts, and compact robotic arm pivots.

Professional Installation and Maintenance Tips

• Press on the Correct Ring During Installation: When pressing the bearing onto a 4mm shaft, apply force solely to the inner ring. When inserting into a housing bore, apply force only to the outer ring/flange. Pressing across the shields or rolling elements can cause brinelling (raceway denting) and rough rotation.
• Use Shims When Stacking Bearings: If pairing two F604ZZ bearings together as a belt idler, place a thin 4mm precision washer or shim between the inner rings if needed to ensure the outer rings rotate freely without binding against the mounting screw head.
• Do Not Wash Out Factory Grease: Avoid soaking shielded (ZZ) bearings in harsh solvents or degreasers unless immediately re-packing them with appropriate high-speed synthetic grease, as dry metal-on-metal contact will cause rapid friction wear.
• Ensure Shaft Fits Smoothly: Use precision-ground 4mm shafts (h6 or g6 tolerance). Never hammer a bearing onto an oversized or burred screw thread, as this can distort the inner ring and jam the internal steel balls.