An encoder is a device that encodes signals (such as bitstreams) or data and converts them into a signal format that can be used for communication, transmission, and storage. Encoders can be broadly categorized based on their application: commercial grade and chip-level, economy grade, standard industrial grade, and various special industrial grades.
Commercial grade vs. chip grade:
For example, the encoders inside printers and magnetic card readers have a simple structure, often lacking a casing. Temperature, dustproofing, waterproofing, and electromagnetic compatibility are almost irrelevant, and they are extremely inexpensive. Chip-level encoders: These are very inexpensive and are currently provided by some foreign semiconductor chip manufacturers or simply packaged by downstream manufacturers. They have no casing or only a simple casing, and power and signal processing are minimal. They are suitable for manufacturers' secondary circuit development. The receiving line should not be more than 50cm away from the encoder. Some flow meter and valve regulator manufacturers choose this level. The protection, electromagnetic compatibility, and anti-interference of this type of encoder should be considered by the secondary development manufacturer; otherwise, damage can easily occur.
Economy and Industrial Grades:
Economy-grade embroidery uses simple packaging and processing, making it suitable for standalone equipment such as embroidery machines. However, the main characteristic of economy-grade embroidery is its cost-effectiveness compared to industrial-grade embroidery. Its design and material selection are geared towards affordability, making it unsuitable for large equipment, assembly lines, and engineering projects. In contrast, industrial-grade embroidery is designed, uses materials, and undergoes testing according to standard industrial requirements, making it suitable for various industrial equipment, assembly lines, and engineering projects. The typical differences between the two grades can be seen in their appearance and specifications, as follows:
1. Bearings
Economy-grade shaft bearings are single-bearing (some chip-level encoders don't even use ball bearings). Some economy-grade bearings are externally secured by clips, and you can see the retaining ring (as shown in the picture below). Some are more clever , adding a part in front of the bearing to cover the retaining ring. After a period of use, the single-bearing bearing's accuracy naturally becomes difficult to guarantee due to the single support, and its sealing performance is also worse. Industrial-grade encoders, on the other hand, use a double ball bearing structure with multiple balancing support points, resulting in higher shaft precision, impact resistance, and sealing performance. The double-bearing structure requires very high machining and installation precision for the shaft, because if the precision is insufficient, the interaction between the two bearings will cause a "sticking" feeling when rotating. Therefore, you can feel the shaft's precision by turning it. Strangely, some encoders labeled as "high-precision" also use a single-bearing method. I don't know how their "high precision" is guaranteed in long-term use.
2. Shell encapsulation
Economy-grade encoders rely on three screws for enclosure fixation (if three screws are used on the outer diameter of the encoder housing, the screws' insertion can cause slight deformation of the outer circle, affecting sealing performance). Industrial-grade encoders, on the other hand, do not use screws; the seal is achieved through a compression seal combined with an O-ring. Some users wonder how encoders can still be damaged when the working environment is free of dust and moisture. However, encoders inevitably experience power-on and power-off cycles. The temperature difference caused by thermal expansion and contraction creates a pressure difference between the inside and outside. Encoders with poor protection levels can produce "breathing" moisture. This pressure difference draws moisture into the encoder, and over time, it can damage optical components and electrical circuits, affecting usability or even destroying the encoder. Typical examples include inaccurate readings or unstable signals after a period of use. Some encoders experience problems at higher temperatures, which is often attributed to temperature issues, but is actually a sealing problem.
3. Temperature rating
Economy-grade electronic components typically operate within a temperature range of -10°C to 60°C, rarely exceeding 70°C. Industrial-grade components, on the other hand, generally operate from -20°C to 70°C, with better ones reaching -25°C to 80°C. The temperature rating reflects the grade of internal components used. It's important to know that most consumer-grade electronic components operate at temperatures up to 55°C or 60°C, while premium industrial-grade components exceeding 70°C often cost more than twice as much. The difference in grade isn't just about temperature; it also reflects the probability of failure during use. A wide temperature range not only means being suitable for these extreme temperature ranges but also indicates good resistance to temperature shocks and fluctuations. Some users mistakenly believe that their environment doesn't reach these extreme temperature ranges, and that 55°C is sufficient. However, they overlook the potential damage to components and the probability of internal chip failure caused by temperature shocks during power-on and power-off cycles.
4. Output signal and power supply
Economy-grade encoders mostly use open-collector PNP or NPN outputs, lacking polarity and short-circuit protection for power and signals. The open-collector output is single-sided and unbalanced. Interference immunity and long-distance signal transmission are poor, making them unsuitable for certain applications, especially engineering projects. Industrial-grade encoders, on the other hand, use push-pull outputs (combining PNP and NPN), differential-driven balanced outputs, or other standard industrial signals. For example, some economy-grade encoders are labeled SSI, but these are not standard industrial RS422 SSI signals; the error is only discovered after connection. Industrial-grade power supplies operate at 10-30Vdc, with minimal voltage drop attenuation over long distances, and signal lines often have short-circuit protection. Many industrial environments experience brief moments of power instability; a wide power supply range is crucial to ensure encoder operation is unaffected, while polarity and short-circuit protection prevent damage from incorrect wiring or accidental incidents during engineering and maintenance.
5. Electromagnetic compatibility
Economic-grade EMC levels are not very high and are basically not specially designed for this purpose, while industrial-grade EMC levels generally need to reach level 2 or above (testing standards and certificates must be provided), including standard tests such as surge, fast burst, and electrostatic discharge. These indicators are related to the stable operation of the encoder in complex electrical environments.
6. Internal parts
Internal components cannot be seen from the appearance or the parameter table. Industrial-grade components are often highly integrated and modular, with surface-mount soldered circuit boards and three-proof treatment.
7. Procedure Testing, Standards, and Final Costs
Standard industrial-grade encoders, due to their structural design and component selection, can have component costs that are several times higher than those of economy-grade encoders. In addition, their testing procedures and standards are also higher than those of economy-grade encoders. Therefore, the cost of industrial-grade encoders is much higher than that of economy-grade encoders.
Various special industrial grades: such as explosion-proof grade, automotive electronics grade, high temperature grade (greater than 100 degrees Celsius), water immersion grade, heavy load grade, etc.
