688ZZ Ball Bearing بيرنج مدور

Bearing Type

Deep Groove Ball Bearing (Single Row, Miniature)

Designation

688ZZ (or sometimes 688-2Z)

Dimensions (ID x OD x Width)

8mm x 16mm x 5mm <br> - Inner Diameter (ID): 8mm (bore for the shaft) <br> - Outer Diameter (OD): 16mm <br> - Width (B): 5mm

Shield/Seal Type

ZZ / 2Z (Double Shielded): Features a metal shield on both sides of the bearing. These non-contact shields help protect the internal rolling elements from dust, dirt, and contaminants while retaining the lubricant (grease). They allow for higher rotational speeds compared to rubber seals (2RS).

Material

Bearing Steel (e.g., GCr15 / Chrome Steel): High-quality steel that provides excellent hardness, wear resistance, and long service life.

Rolling Elements

Steel Balls

Cage/Retainer Material

Typically pressed steel or synthetic resin (nylon/polymer) to separate the balls and maintain even spacing.

Load Direction

Primarily designed to handle Radial Loads. It can also accommodate moderate Axial Loads in both directions.

Precision Grade

Often specified with ABEC ratings (e.g., ABEC-1, ABEC-3, ABEC-5). Higher ABEC ratings indicate tighter tolerances and higher precision.

Lubrication

Pre-lubricated with grease by the manufacturer, making them "lubricated for life" in many common applications. The shields help retain this grease.

Limiting Speed

High rotational speeds, typically ranging from 30,000 to 45,000 RPM (revolutions per minute) depending on the quality and lubrication.

Operating Temperature

Generally suitable for temperatures from -20°C to +80°C (or up to +110°C, depending on the lubricant and cage material).

Noise Level

Designed for low noise and vibration, especially in higher precision grades.

Weight

Very lightweight, typically a few grams per bearing.