6705 Decoder Bearing

6705 Decoder Bearing — Precision Rotary Encoder Bearing by MTWB

The MTWB 6705 Decoder Bearing is a precision-engineered deep groove ball bearing specifically optimized for rotary encoder and sensor applications. Unlike general-purpose miniature bearings, the 6705 Decoder Bearing is designed to deliver stable rotational accuracy and minimal torque variation, ensuring reliable signal output from encoder systems in industrial automation, servo motors, and precision measurement equipment. Every MTWB decoder bearing undergoes application-specific engineering review before production, with raceway geometry, internal clearance, and lubrication selected to match the actual operating conditions of the encoder system.

Technical Specifications

Parameter Value
Bearing Designation: 6705 (Decoder Bearing)
Bore Diameter (d): 25 mm
Outer Diameter (D): 32 mm
Width (B): 4 mm
Chamfer (r min.): 0.2 mm
Dynamic Load Rating (Cr): 1.35 kN
Static Load Rating (C0r): 0.840 kN
Fatigue Load Limit (Cu): 0.035 kN
Limiting Speed (Grease): 19,000 rpm
Limiting Speed (Oil): 22,000 rpm
Mass (Reference): 0.006 kg
Precision Grade: ABEC / P6 or higher
Material: GCr15 / G95Cr18 bearing steel
Standard: ISO 9001:2015

Dimensions and load ratings conform to ISO 15:2017 boundary dimension standards.

Key Features

Encoder-Optimized Raceway Geometry: The raceway is specifically designed for rotation accuracy, minimizing runout and angular error that could distort encoder signal output. Super-finished raceway surfaces provide mirror-like contact areas for smooth, consistent ball tracking.

Low Torque and Low Friction: Internal dimensions are adjusted for lubrication efficiency, resulting in reduced rotational torque — a critical factor for encoder bearings where torque fluctuation directly affects measurement precision.

Stable Signal Output: The combination of high rotational accuracy and low vibration ensures that the encoder's magnetic or optical sensor receives a clean, consistent signal without the "quiver" or angle error that low-quality bearings can introduce.

Wide Temperature Range Grease: High-performance, quiet, wide-temperature-range grease is selected to maintain consistent lubrication across diverse operating environments, from cold-start conditions to sustained high-speed operation.

High-Grade Bearing Steel: Manufactured from Jiangyin Xingcheng special steel (high-graded bearing steel), with optional G95Cr18 and GCr15 materials for enhanced durability and dimensional stability.

Low Vibration and Noise: Designed to maintain low vibration noise levels, with 100% noise inspection available for decoder bearing batches upon request.

Application

The 6705 Decoder Bearing is purpose-built for applications where rotational position feedback is critical:

Rotary Encoders and Sensor Bearings: Integrated encoder systems in servo motors, DC motors, and hydraulic motors requiring precise speed and direction detection.

Industrial Automation Control: Servo motor feedback systems, PLC-controlled actuators, and precision positioning stages.

Robotics and Motion Control: Robot joints and reducers where compact encoder-integrated bearings support both rotation and position sensing.

Precision Measurement Equipment: Optical encoders, magnetic encoder systems, and any application where bearing runout translates directly into measurement error.

Motor Feedback Systems: AC and DC servo motors requiring reliable rotational speed and direction signals for closed-loop control.

Noise Testing and Qualification

Low Noise EMQ Bearings are manufactured by superfinishing rolling contact surfaces to mirror-like finishes and are typically 100% noise-tested using specialized equipment such as the Anderon meter before final lubrication and packaging. EMQ ratings (ZV2, ZV3, ZV4) indicate increasingly stringent noise and vibration levels, with ZV3/V4 required for high-precision motors.

Power Hand Tool Bearings also benefit from EMQ-level manufacturing, but the critical additional requirement is preload specification. In power hand tool applications, internal clearance must be removed through axial preload to establish a proper contact angle, enabling stable operation at speeds that can reach 60,000 RPM. Without correct preload, even a quiet bearing will generate excessive vibration in a power tool.

MTWB Decoder Bearings are qualified differently. While they also benefit from low noise characteristics, the primary qualification criterion is rotational accuracy and torque consistency. A decoder bearing with excellent noise performance but inconsistent torque would still produce poor encoder signal quality. MTWB decoder bearings are therefore validated for runout, starting torque, and running torque variation in addition to standard noise testing.

Lubrication Requirements

EMQ bearings require "clean" grease with low particle content to maintain noise performance over time. Power tool bearings require grease that can withstand high temperatures and maintain film strength under heavy preload. MTWB decoder bearings use a specialized low-torque grease formulation that minimizes viscoelastic resistance while maintaining stable lubrication — because excessive grease drag directly increases the torque required to rotate the encoder shaft, introducing measurement error.

When to Choose Which

●Choose Decoder Bearing when the bearing is part of a position-sensing or speed-feedback loop and signal accuracy is the top priority.

●Choose Power Hand Tool Bearing when the bearing must support high-speed rotation under intermittent heavy loads with preload applied.

●Choose Low Noise EMQ Bearing when the application is a standard electric motor where acoustic noise and vibration are the primary concerns, and precise position feedback is not required.

MTWB Original Design & Manufacturing Advantages

Application-First Engineering. Every MTWB decoder bearing project begins with an engineering review of the customer's actual working conditions — rotational speed, load profile, temperature range, and signal accuracy requirements — rather than simply selecting a catalog model. MTWB engineers optimize raceway geometry, internal clearance, and lubrication to match the specific encoder system.

Customization Capabilities. MTWB offers full OEM/ODM bearing customization, including special raceway profiles, non-standard internal dimensions, custom sealing solutions (contact seals, non-contact seals, and grease retention designs), and material selection ranging from standard GCr15 to G95Cr18 and corrosion-resistant stainless steel.

Integrated Quality Management. MTWB combines Hong Kong quality management systems with efficient manufacturing resources in mainland China, delivering precision bearings that meet ISO 9001:2015 standards and ABEC/P6 or higher precision grades. All bearings are manufactured with stringent control at every stage, from raw material steel tubes to finished product.

Proven OEM Track Record. With more than 18 years of manufacturing experience and support for over 100 OEM customers across robotics, medical equipment, automation, and electric mobility sectors, MTWB is a trusted bearing partner for international brands seeking application-specific solutions at competitive cost.