Correlated Magnetics: A New Twist in Magnetics, Controlling Magnetic Force with a Twist

The attractive force between two conventional magnets is primarily a function of how much of their surfaces are in contact. For two fully aligned round magnets, this attractive force will be the same for any rotational alignment of the two round magnets.  On the other hand, conventional magnets having non-round shapes will have an attractive force that varies as one magnet is turned relative to the other as the contacting surface area between the two magnets varies with rotation. 

Correlated magnetic structures such as printed Coded Magnets™ have multiple magnetic sources having positions and polarities in accordance with a code.  Two complementary Coded Magnets will achieve a peak attractive force when their complementary magnetic source pairs align.  For any other translational alignment or rotational alignment the attractive force between the two Coded Magnets is substantially less than the peak attractive force because magnetic sources of the two Coded Magnets will cancel each other.  As seen in Fig. 1, with only a few degrees rotation off of their rotational alignment position, the attractive force of two Coded Magnets drops drastically as the magnetic sources begin to cancel as the two Coded Magnets decorrelate.  

Figure 1. Correlated Magnetic Structures Decorrelate With Only a Few Degrees Rotation

Referring to Fig, 1, the geometry of the square magnets can be seen in both curves, where there are peaks at 90° and 180°when their full surface areas are fully in contact.  In between these peaks, the conventional magnets have a curved shape that is strictly a function of the varying of the surface area in contact between the two magnets for each rotational alignment.  Again, had the two conventional magnets been round, the attractive force remains the same for all rotational alignments.  Clearly, correlated magnetic structures make it possible to control their magnetic force from a peak attractive force to a relatively weak attractive or even repulsive force with a twist of a few degrees. 

Of importance is the torque that must be applied to rotate the one Coded Magnet relative to another in order move off of their peak attractive force, which is18 pounds of force in the present example.  Fig. 2 presents the torque required to turn one Coded Magnet 360°relative to the other Coded Magnet. 

Figure 2. Correlated Magnetic Structures Decorrelate With Only a Few Degrees Rotation

As can be seen in Fig. 2, for one direction of rotation it takes about 1 inch-pound of torque to twist one Coded Magnet off of its peak attractive force position.  In the opposite direction of rotation it takes about ¾ inch-pounds of torque to twist one Coded Magnet off of its peak attractive force position.  The torque is determined by the specific codes (i.e., Code A and A’) used to program the Coded Magnets, so it scales linearly with size.  A torque of 1 inch-pound to twist apart Coded Magnets having 18 pounds of peak attractive force equates to separating 200 pounds of force by applying 2.78 pounds of force to a four inch lever, separating one ton of force by applying 9.27 pounds of force to a 1 foot long lever, separating 10 tons of force by applying 30.9 pounds of force to a 3 foot long lever, etc.  However, those extrapolations assumed use of same 25 magnetic source pattern used in the example Coded Magnets but with larger and larger magnetic sources.  In practice, far more magnetic sources would be used to produce such very strong Coded Magnets in which case far greater code resolution would result in a sharper correlation thumbtack meaning it would require even less torque to twist them.  Overall, the ability to control strong magnetic forces with a relatively minor twist is truly amazing.