Correlated Magnetics: Precision Object Alignment

Conventional magnets are not commonly used for precision alignment applications because even the most powerful magnets can achieve only about 96-97% precision for translational alignment purposes. That translates to a margin of error of 6 to 8% from a desired precision point. Moreover, conventional magnets are not commonly used for rotational alignment purposes because their fundamental properties do not lend themselves for doing so. In Fig. 1, two bar magnets and two round magnets are shown in aligned and partially aligned relative orientations.

Fig. 1. Alignment and Partial Alignment of Conventional Bar Magnets and Round Magnets

Conventional magnets may be handled or otherwise physically constrained to achieve substantial alignment but they cannot be depended upon to align themselves because they may only partially align if the force between their surfaces plus friction is at least equal to their torque.  

With correlated magnetic structures, there are multiple magnetic sources over which alignment error is averaged or integrated out with the number of sources. Consequently, the greater the number of magnetic sources of two complementary correlated magnetic structures, the greater their alignment precision. The alignment behavior can be further described using the horizontal components of their spatial force function. Fig. 2 depicts various views of a horizontal spatial force function between two Coded Magnets™. This can be described as a ‘precision volcano’ combined with a ‘precision vortex.’ 

Fig. 2. Horizontal Spatial Force Function of Two Coded Magnets Programmed Using Code A and A’

Referring to Fig. 2, as two correlated magnetic structures are brought towards their precision translational and rotational alignment position, horizontal components of their spatial forces increase rapidly. This rapid increase in force is consistent with their overall spatial force function as shown in Fig. 3. But, as the two structures approach their precision alignment, there is a steep transition from a horizontal attractive force to a vertical attractive force.  This transition results in a precision translational and rotational alignment that is limited only by friction. The steepness of the outer faces of the precision volcano and the peak attractive forces around its rim will increase with the number of magnetic sources that make up the correlated magnetic structures. These same peak attractive forces are also the top of the precision vortex where the steepness of its inner walls also increase with the number of magnetic sources of the correlated magnetic structures. 

Fig. 3. Spatial Force Function of Two Coded Magnets Programmed Using Code A and A’

By increasing the number of magnetic sources included in the correlated magnetic sources, by reducing friction, and by varying the coding used to program such structures, a designer can produce structures that meet established precision alignment criteria.  As such, correlated magnetic structures are an ideal mechanism for precision translational and rotational object alignment and attachment.