Dexter Magnetic Technologies

United States

A magnetic coupling is a device that is capable of transmitting force through space without physical contact. Attractive and repulsive magnetic forces are harnessed to perform work in either a linear or rotary fashion. In its simplest form, a magnetic coupling is comprised of two components: a driver and a follower. The driver is the portion of the mechanism connected to the prime mover (motor). Through magnetic interaction, the follower reacts to the motion of the driver, resulting in a non-contact transmission of mechanical energy. This non-contact power transmission has multiple benefits: Isolation of Components, which minimizes or eliminates mechanical vibrations through magnetic damping and allows for the insertion of a mechanical barrier between the driver and follower to separate environments and allow operation under pressure differentials. High Tolerance of Axial, Radial and Angular Misalignment between the prime mover and load. Allowance of Speed Variation and Regulation between the prime mover and load. We offer three types of custom magnetic couplings: Synchronous (Class 1) Dexter syncronous coaxial coupling Dexter syncronous face-to-face coupling Dexter syncronous linear coaxial coupling Dexter synchronous linear planar coupling As the name implies, this coupling is a synchronous version that inherently results in a 1:1 relationship between the motion of the driver and follower. As taught in grade schools, like magnetic poles (North-North and South-South) repel each other while opposite poles (North-South) attract, synchronous couplings exploit these “attractive” and “repulsive” characteristics to produce motion. By placing an array of alternating pole permanent magnets (N-S-N-S) on the driver and an equivalent array of alternating pole permanent magnets on the follower, a “coupled” magnetic circuit is produced with each North and South pole in the driver linked to each respective South and North pole of the follower. As the driver moves with respect to the follower, the magnet poles start to overlap one another, leading to a “push-pull” effect and consequent motion. The magnitude of the resultant force depends not only on the amount of overlap, but also on the chosen magnetic material’s characteristics and separation distance between the driver and follower. At some displacement, however, the peak force producing capabilities of the coupling are achieved. Displacement beyond this point results in a decoupling. This decoupling manifests itself as a ratcheting action resulting from like magnetic poles is the driver and follower repelling each other. Unlike its mechanical equivalent, however, the decoupling does not, generally, lead to permanent damage; and synchronization is reinitiated at the next magnetic pole coupling point. Pros: Greatest volumetric force density. Cons: Limited to a 1:1 motion ratio Use: Devices that require direct coupling with no slip during operation.

Dipoles consist of a pair of magnets across a gap. They come in many shapessizes and the magnets are usually mounted on a steel frame (also called a yoke) for magnetic efficiency, magnetic shielding andor mechanical strength. Dipoles are used when an application requires a specific magnetic field strength and uniformity over a specific volume. Pole pieces are sometimes used to enhance uniformity within the gap.At Dexter, we have built hundreds of different types of dipoles, each optimized for a particular application. Field strengths have ranged as high as 3.0 Tesla (30, 000 Gauss). Generally, higher fields are associated with small air gaps. Higher uniformity is generally associated with large air gaps. Dipoles are used to: Calibrateinitialize magnetic sensors Erase computer hard disk drives Orient thin layers of magnetic material as they are deposited as thin films Divert or focus beams of energized particles We’ve used the dipole principle in these designs:

Magnetic Resonance Imaging (MRI) was known as Nuclear Magnetic Resonance (NMR) until the ‘nuclear’ connotation became unpopular, but both names denote the Magnetic Resonance (MR) principle involved. Besides the MRI machines one finds in hospitals, magnetic resonance devices are commonly in devices used to ensure proper chemistry material mix, such as equipment used to monitor quality of asphalt. MR detects an atom’s gyromagnetic ratio, the ratio of the magnetic dipole moment, due to nuclear spin, to the mechanical angular momentum, to discriminate between elements. Almost every element in the periodic table has an isotope with a non zero nuclear spin, but to be useful the isotope must also be abundant in the volume being analyzed. Therefore, the nuclei of interest in MRI of the human body and other living organisms are those of hydrogen, carbon, nitrogen, sodium, phosphorus, potassium and calcium.MRI system components include: a magnetic dipole to establish a static magnetic field, a gradient coil, an RF coil to produce an alternating magnetic field at 90° to the static magnetic field, and an antenna coil. In operation, protons in the sample volume are oriented by the static field, and caused to precess by the alternating RF magnetic field. When power to the RF coil is turned off, the magnetic moment of the protons realigns with the static magnetic field. The energy change involved in realignment of the magnetic moments is measured as a small RF signal by the antenna coil and a Fourier transform of signal frequency and phase produces data used to construct a distinctive image.

sotropic magnets, such as Bonded Nd-Fe-B, are unoriented and have no preferred direction; therefore it is possible to magnetize them in any direction. Almost all other materials are anisotropic and have a preferred direction of magnetization. They will exhibit the best magnetic properties when magnetized in the direction of the grain. Higher magnetic flux densities can be achieved with anisotropic magnets that are magnetized in their direction of orientation than with isotropic magnets. The magnetization patterns for your project can be created with the following orientations: Need more details on magnetization patterns?

Separators are used to separate magnetic materials, such as magnetic beads, from the non-magnetic medium in a vessel. The magnetic separator unit pulls the magnetic beads and holds them using magnetic forces allowing the medium to be removed. Dexter’s LifeSep™ magnetic separators provide an immediate starting point for performing rapid separations in single tubesvessels as well as microtitre plates. Select from one of our patented standard separators or personally work with our team of design engineers to create a custom separator product to fit your needs. Our magnetic separators: Improve the rate of separation Improve wall retention Reduce cycle time Maximize yield Dexter offers standard vessel and tray magnetic bead separation and custom solutions. If you are involved in the design of clinical diagnostic equipment or automated high-throughput applications that rely on biomagnetic bead processing for improving productivity in biotechnology and life science research, Dexter will provide you with results. Learn more about our magnetic separators for medical solutions.

ssisting disk producers to accelerate the slow process of servo erasing disk media, we have developed Dexter EraseTrack Bulk Eraser, a patented universal bulk disk eraser. Dexter EraseTrack can erase 25 disk cassettes faster that servo erasing a single disk. By combining its increased speed and capacity with a permanent magnet structure that does not require power or maintenance, Dexter EraseTrack provides disk producers with incredible process time savings. Benefits: No electricity or maintenance required. No water cooling required. Can be easily integrated into conveyor system for final packaging and distribution. Permanent magnet construction provides no cycle time limitation due to heating or power supply constraints. Erases multiple disks in a single pass. Approximately 25 times faster than the servo erase process creating increased throughput. Features:Features: Designed to erase LMR & PMR disk media. 1 Tesla field (minimum) in erasure plane. Tilting mechanism for angle adjustment. Designed for 2-stacked longitudinal cassettes or a single cassette PMR. Cassette opening 5.4 inches in Y-axis, 10 inches in X-asis. Lifting hooks. Field outside box to be lower than 50 gauss, except at the gap opening where it can be close to 80 gauss. Constructed with clean room compatible materials. Warning labels for strong magnetic field. Approximate weight 5, 800 pounds.

Magnetic sensors indirectly measure properties such as direction, position, rotation, angle and current by detecting the magnetic field and its changes. Compared to other direct methods, such as optical or mechanical sensor, most magnetic sensors require some signal processing to get the property of interest. They provide reliable data without physical contact even in adverse conditions such as dirt, vibration, moisture, hazardous gas and oil, etc. The most widely used magnetic sensors are variable reluctance, hall effect and reed switch. Automotive crash safety systems use sensors based on a holding mechanism that can be closed or open using electrical current. Hall effect sensors vary the output voltage in response to the changes in magnetic field. Reed switches have two overlapping ferromagnetic blades (reeds) hermetically sealed in a glass tube. When a magnetic field comes to the vicinity of a reed switch, the reeds are magnetized and attract each other, therefore close an electric circuit. Sensor magnets can be simple as a bar or ring magnet for reed sensors, but can also be as intricate and precise as those used in high definition measurements. Such examples are high resolution magnetic encoder magnets. Austria Microsystems makes high performance absolute and incremental linear magnetic encoder ICs, ranging from 8- to 12-bit resolution. One of the encoders require multipole strip or ring magnets, with 1mm±0.024mm pole width. We are proud to be a partner and magnet supplier for a wide range of Austria Microsystems sensor products.

Microwave circulators and isolators are used primarily in radar and communication systems. These devices typically consist of a ground plane, microwave ferrite and a permanent magnet. These devices are critical in the switching and routing of microwave energy. An isolator is analogous to a diode in a DC circuit. A circulator adds a third port and is used primarily to isolate a transmitter and a receiver from a single port. At Dexter, we also offer the ability to calibrate magnets for circulators andor pre-stabilize them for high-temperature environments.When working with our engineering group, you might be asked: What is the highest temperature the assembly will experience? What is the minimum magnetic strength and how large of a volume is required? Various magnetic materials respond differently to temperature changes. How much of a variation can your assembly tolerate? Are there any harsh environmental conditions (such as water, corrosive gases, etc)?

We design motors and actuators with features such as: High force-to-mass ratios High-speed moving coil designs Capability of withstanding harsh environments. We have extensive experience in designing and producing rotory motors, actuators and voice coil motors. End uses for these devices include semiconductor capital equipment, missile guidance gyros and fin motors, industrial shaker assemblies and factory automation equipment. TYPES We have extensive experience in the design and production of: rotory motors, actuators, and voice coil motors. End uses include semiconductor capital equipment, missile guidance gyros and fin motors, industrial shaker assemblies and factory automation equipment.

Magnetic sensors indirectly measure properties such as direction, position, rotation, angle and current by detecting the magnetic field and its changes. Compared to other direct methods, such as optical or mechanical sensor, most magnetic sensors require some signal processing to get the property of interest. They provide reliable data without physical contact even in adverse conditions such as dirt, vibration, moisture, hazardous gas and oil, etc. The most widely used magnetic sensors are variable reluctance, hall effect and reed switch. Automotive crash safety systems use sensors based on a holding mechanism that can be closed or open using electrical current. Hall effect sensors vary the output voltage in response to the changes in magnetic field. Reed switches have two overlapping ferromagnetic blades (reeds) hermetically sealed in a glass tube. When a magnetic field comes to the vicinity of a reed switch, the reeds are magnetized and attract each other, therefore close an electric circuit. Sensor magnets can be simple as a bar or ring magnet for reed sensors, but can also be as intricate and precise as those used in high definition measurements. Such examples are high resolution magnetic encoder magnets. Austria Microsystems makes high performance absolute and incremental linear magnetic encoder ICs, ranging from 8- to 12-bit resolution. One of the encoders require multipole strip or ring magnets, with 1mm±0.024mm pole width. We are proud to be a partner and magnet supplier for a wide range of Austria Microsystems sensor products.

We design motors and actuators with features such as: High force-to-mass ratios High-speed moving coil designs Capability of withstanding harsh environments. We have extensive experience in designing and producing rotory motors, actuators and voice coil motors. End uses for these devices include semiconductor capital equipment, missile guidance gyros and fin motors, industrial shaker assemblies and factory automation equipment. TYPES We have extensive experience in the design and production of: rotory motors, actuators, and voice coil motors. End uses include semiconductor capital equipment, missile guidance gyros and fin motors, industrial shaker assemblies and factory automation equipment.