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P16A Magnet Target Wheel


Bonded multi-pole magnet rotors are used in a wide variety of speed and commutation applications such as to rotary encoders, speedometers and machine controls. Three standard grades of magnetic materials are offered to fulfill a broad spectrum of magnetic field requirements along with a high resistance to demagnetization. Combined with a Nylon polymer binder, they offer excellent dimensional control and tough environmental endurance. Multi-pole rotors can be modified to have other pole patterns, custom compounded binders, or metal inserts for specialized applications.



  • Rugged, chip free construction
  • Wide range of pole counts
  • Three grades of magnetic materials
  • High resistance to demagnetization
  • Operation from -40 to 125 degrees C
  • Well suited for general industrial environments
  • Recommended attachment method: Adhesive bonding
  • Many additional, non stocked pole counts available
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Other P16 Series Configurations



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Number of Poles Magnalox 300 Neobond 12M Neobond 30M
2 P16A25R2 P16A50R2 P16A75R2
4 P16A25R4 P16A50R4 P16A75R4
8 P16A25R8 P16A50R8 P16A75R8
16 P16A25R16 P16A50R16 P16A75R16
30 P16A25R30 P16A50R30 P16A75R30
40 P16A25R40 P16A50R40 P16A75R40
60 P16A25R60 P16A50R60 P16A75R60

The following data was developed as a design guide for the popular P16A magnet target wheel. The graphs below are plots of the lowest magnetic fields expected under typical manufacturing, environmental and dimensional limits. There is a graph for each of the various number of magnetic poles available on a target wheel. Within each graph are plots for three grades of magnetic materials. These three magnetic materials represent the standard materials available that are stocked but are in no way a limit to the magnetic materials available for custom products.  If information is needed for other specific target wheels, please feel free to contact the factory directly for assistance.

To use the graphs below, the total gap of the magnetic circuit must be known. The total gap of the magnetic circuit is made up of a number of different parts.

·        The first is the air potion of the total gap. Being a non-contact device, there is always a space between the magnet surface and the sensor package. This space is required so that the two components are never in contact when in use. Because of various dimensional stack-ups in the system design, a maximum air gap would be expected under a worst case situation In some applications it is necessary for the sensor to be on the opposite side of a non-magnetic barrier than the target wheel is located.

·        The thickness of this non-magnetic barrier is a second source of gap that makes up the total gap.

·        The last source that makes up the total gap comes from the sensor itself. The magnetically active sensing element is located a small distance within the sensor package. This is required to protect the sensing device from physical damage. The data sheet for the sensor should indicate the package depth of the active element. If this value is not specified, contact the supplier.

The arithmetic sum of these three sources of gap will result in the total gap of the magnetic circuit. 

The graphs can be used in a number of different ways but there are four variables that are being investigated. The four variables are total gap, minimum magnetic field available (to operate the sensor), number of alternating magnetic poles and magnetic material. Any of these variable can be investigated to determine the most efficient design. The most important consideration when reviewing the options for a particular application is to keep the total gap as small as possible since the magnetic field rapidly decreases with the total gap. Another consideration is that a larger diameter magnet target will allow the operation at a larger total gap for the same number of poles.

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