Technical Contrasts

Why are Magnetic Encoders heavier duty than Optical Encoders?
Quite simply: Optical encoders are vulnerable to three kinds of damage

  • The optical disk may shatter during vibration or impact.
  • The bearings fail due to stresses.
  • Oil, dirt, or water get inside the encoder due to seal failure.

Most styles of encoders come sealed from the factory. Over time temperature cycling causes pressure changes and seals fail, which creates a path to the inside of the encoder. Often, the cause of the problem is moist air which enters the encoder and then condenses, rains, or freezes inside the encoder.

Why do contaminants (dirt, oil, water…) cause optical encoder failure, and not magnetic encoder failure?
Optical encoders need to see tiny lines on a disk accurately; they make errors when there is any type of contamination on the disk. Magnetic encoders do not make errors due to contamination.

Many optical encoders manufacturers attempt to reduce the causes of optical encoder failure and resulting sensor crashes by controlling the gap between the optical sensing element and the optical disk. This is expensive and requires the use of a separate bearing system integral to the encoder. Some will claim use of only shatterproof optical disks but these disks are still susceptible mechanical scratching. They will claim to use superior seals to keep contamination out and withstand a greater range of temperatures, but all these ‘band-aids’ only add cost.

Phoenix America Magnetic Encoders withstand dust, dirt, oil, water, and heavy temperature cycling while providing the longest life and most reliable feedback. Magnetic technology enables the sensor to “see” even when conditions inside the encoder look like a rainstorm of oil or water! Phoenix America Inc. magnetic encoders even eliminate the bearings increasing reliability even further.

How do Magnetic Encoders handle heavy loads and stress on bearings?
In applications utilizing gears or drive belts, excessive radial (side) lading on a shaft can shorten the life of a conventional optical encoder or even destroy them. Other technology need to specify anticipated side loads. In order to handle heavier loads and shock (200 g’s), the competition needs to call on ‘Ultra heavy duty’ encoders. The Phoenix America Inc. magnetic encoder solution is ‘non-contacting’ and utilizes no bearings of it’s own – it is truly the heavy load answer.

While our competitors handle heavy loads through features such as “ a three-bearing design that enables high axial and radial shaft loading, while sustaining speeds in excess of 5000rev/min” using “heavy duty shafts” – the Phoenix America magnetic encoder solution is simply to take advantage of the bearing system all ready existing. The competitive solutions simply add redundancy and cost.

So when you are dealing with belt pulleys or other load-producing hardware choose a simple, less costly magnetic solution and stop attaching to redundant encoder shafts or adding bulky and expensive bearing isolation modules. While others brag about doubling the bearing life of incremental encoders - Phoenix America Inc. magnetic encoder eliminated the failure mechanism all together.

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