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Correlated magnetics provides a new set of mechanical tools for design and engineering. Whereas ordinary magnets only repel or attract – and their force profiles are determined only by magnet geometry and material – coded magnets from CMR can be programmed to deliver custom force profiles, including repel and attract forces acting simultaneously, opening up a broad range of valuable behaviors for mechanical design. | |
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Programmability
The patterns of magnetic elements (maxels) shown at right are an example of programmed behavior. This pair is designed to produce a peak attraction force in only one orientation, and to release the attraction force when rotated.
The maxel polarity is indicated with red (north pole facing out) and blue (south pole facing out).
Note the reflected symmetry of the design: this will ensure that all 101 maxels will produce an attraction force when aligned with faces together. This design produces a peak attraction force of more than 34lbs.
However, at any other orientation – whether the Polymagnets™ are rotated or translated – the patterns of maxels begin to cancel each other out. The peak attraction force relaxes to a prescribed residual attraction force. In this case, a residual attraction force of only 6.8lbs at a rotation of 20° (a ratio of about 5 to 1).
This coded magnet pair latch together with nearly 50% stronger attachment force (compared to conventional magnets), yet release easily with a twist.
Polymagnets™ can be tailored to deliver specific forces or a range of forces to fit your application. Attach and release forces – even the release behavior – can be engineered by varying a number of design parameters in correlated magnetics.
Scalability
Any prescribed behavior can be scaled up or down as the application may require. Shown at right are a SwirlCode™ pattern pair rendered as 529 maxels on 3” disk magnets.
The behavior is similar to that of the smaller SwirlCode magnet pair, and the measured forces for these coded magnets are shown in the graph below.
With 95lbs peak attraction force when aligned in the correlated position, these are nearly 300% stronger than conventional magnets. When the patterns are decorrelated, the SwirlCode 529 magnets relax to only 17lbs coupling force.
Programmed behavior translates to the other end of the scale as well. The smaller the maxels, the more complex the patterns can be. Magnetic elements at the microscale can be used to align components of micro-electromechanical systems (MEMS) and domain-scale maxels can enable nanotechnology.
Multi-level magnetism - HoverField™
Correlated magnetics can control the strength of the magnetic forces and the reach of the magnetic field (see correspnding force-distance profiles at right). And, depending on the polarity of the correlating maxels, the force can be either attract or repel. As such, a magnet pair can be coded to attract at a specified distance and repel at another.
CMR labs have produced just such magnetic devices that attract each other at a distance (far field) and repel each other in close proximity (near field). These devices have taken on the name of Hoverfield and are described below.
The patterns shown at right represent the first codes produced to realize a working HoverField device. The stripes of maxels running across the faces provide a tolerance for misalignment in this east-west direction. The magnets will achieve a stable hovering lock position whether or not the centers coincide.
The force curves shown below right can explain the behavior of the Hoverfield device. The red curve shows the gradual decay of the attraction force coded into the magnet pair. The blue curve shows the steeper profile of the repel force, also coded into the pair. The green curve shows the sum of the forces and depicts the aggregate behavior of the correlated pair.
As the two coded magnets approach each other, they encounter both an increasingly strong attract force and repel force. However, the attract force is dominant until they reach a separation distance of approximately 5cm, at which point the aggregate curve bends toward zero and the attraction force decreases.
At approximately 1.7cm of separation (Dx) the repel force equals the attract force and a stable equilibrium is reached.
The two Hoverfield magnets lock together in contactless attachment at the distance prescribed by the maxel patterns for each of the opposing forces. Watch this:
A radially-symmetric HoverField code has been developed at the CMR labs as well, to provide a hovering lock behavior with tolerance for concentric rotation of the magnets relative to each other. The first Radial HoverField codes are shown at right.
The radial Hoverfield device relies on programmed control of the forces and distances similar to the directional Hoverfield device described previously, except the code provides a tolerance for changes in rotational alignment.
You can see the radial Hoverfield here:
Multi-level magnetism - RepelSnap™
By reversing the relative reach of the attract and repel forces coded into the HoverField devices, we can achieve a coded magnet pair that will repel each other at a distance (far field) and attract each other in close proximity (near field). These devices have taken on the name of RepelSnapTM and are described below.
The patterns shown at right represent the first codes produced to realize a working RepelSnap device. The coded maxel patterns are neither axially nor radially symmetric , and therefore will act as correlated / uncorrelated.
The stripes of maxels running across the faces provide a tolerance for misalignment in this east-west direction. The magnets will achieve a stable hovering lock position whether or not the centers coincide.
The force curve shown below right can explain the behavior of the RepelSnap device. The blue curve shows the sum of the repel and attract forces and depicts the aggregate behavior of the correlated pair.
As the two coded magnets approach each other, they encounter an increasingly strong repel force until they reach a separation distance of approximately one-half inch, at which point the aggregate curve bends toward zero and the repel force decreases.
At approximately two-tenths of an inch of separation the repel force decays to zero, the attract force dominates, and the coded pair will snap together and attach.
The RepelSnap magnets lock together until the coded paterns of maxels are decorrelated. This device was designed to release with a rotation of one magnet relative to the other. Watch this:
And much more - tuned force curves and custom magnet behavior made possible through correlated magnetics.
Example behaviors currently being tested at CMR:
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Copyright 2011 Correlated Magnetics Research™ LLC. All Rights Reserved. |
