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Bearing Seal

Magnetic Encoder with Bearing Seal Supplier | Shaft Rotary Seals OEM
Bearing Seal

Magnetic Encoder with Bearing Seal Supplier | Shaft Rotary Seals OEM

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  • Magnetic Encoder with Bearing Seal Supplier | Shaft Rotary Seals OEM

Description


he Core Concept: An Integrated System

In many applications, especially servo motors and precision industrial automation, these three components work together as an integrated system to deliver reliability, accuracy, and longevity. The key interaction is this:

  • Magnetic Encoders need to be protected from contamination to function accurately.

  • Bearing Seals are the primary defense against contamination.

  • However, standard seals can interfere with the magnetic field of the encoder.

The engineering challenge is to balance excellent sealing with uncompromised encoder performance.

1. Magnetic Encoders

A magnetic encoder is a device that measures rotational position or speed by sensing a magnetic field.

  • How it works: A multi-pole magnetic ring is mounted on the motor shaft. A sensor (usually a Hall-effect or magnetoresistive chip) is positioned nearby, reading the changing magnetic field as the shaft rotates to determine position and speed.

  • Key Advantage (for this context): Non-Contact. Unlike optical encoders, there is no need for a delicate code disk that can be obscured by dust or oil. This makes them inherently more robust against certain types of contamination.

2. Bearing Seals

Bearings are critical for supporting the motor shaft. Their seals are responsible for keeping contaminants out and lubricant in.

  • Types of Seals:

    • Contact Seals (Rubber Lips): Offer excellent sealing but generate friction, which can slightly reduce efficiency and create particulates from wear.

    • Non-Contact Seals (Labyrinth or Gap Seals): Create a tortuous path that contaminants cannot easily cross. They generate no friction but are generally less effective against fine dust or liquid sprays.

3. The Critical Interaction: Seals vs. Magnetic Field

This is the central engineering challenge. The magnetic field from the encoder's ring is relatively weak and can be easily distorted or "shorted" by ferrous metals (like standard steel seals on bearings).



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First, the speed of rotation

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Second, the temperature of the working environment

  Low temperature will reduce the elasticity of rubber and plastic oil seals, resulting in leakage, and even the entire oil seal becomes hard and brittle. High temperature will make the oil seal volume expansion, soft, resulting in the oil seal friction resistance increases rapidly and the pressure resistance decreases. It is recommended that the continuous operating temperature range of ordinary polyurethane or rubber and plastic oil seals be -10 ° C to +80 ° C. For the high temperature and high speed requirements of the working environment, we need to choose to use fluorine rubber and PTFE, high temperature resistance and wear resistance is better, the low temperature environment is generally to -40 degrees, and the rubber performance is tested at high and low temperatures to ensure that the product quality meets the requirements.  

Third, the working pressure of machinery

  The oil seal has a minimum service pressure requirement. Oil seals with low friction and low starting resistance should be selected for low pressure work. Below 2.5MPa, polyurethane oil seal is not suitable; High pressure to consider the oil seal pressure deformation, need to use anti-extrusion stop ring, grooving processing also has special requirements.

Fourth, the working medium

  General sealing media are gasoline, oil, diesel, grease, and some static sealing dust. In addition to selecting the working medium strictly according to the manufacturer's recommendations, it is important to keep the working medium clean. Aging or contamination of the oil will not only cause the components in the system to fail, accelerate the aging and friction of the oil seal, but also the dirt in it may scratch or embed the oil seal, making the seal fail. Therefore, it is necessary to regularly check the quality of the oil and its cleanliness, and replace the oil filter or oil according to the maintenance specifications of the equipment. The air remaining in the oil in the cylinder will be compressed by high pressure, which will cause the oil seal to burn out or even carbonize. In order to avoid this situation, exhaust treatment should be carried out at the initial operation of the hydraulic system. The hydraulic cylinder should also run at low pressure and slow speed for a few minutes to confirm that the residual air in the oil has been drained before it can work normally.