Medical Technology on the Move Low-inertia motors and integrated motion control systems enhance medical and diagnostic devices. How difficult is it to achieve short-distance moves in high-accuracy motor-driven applications? �It�s not difficult at all,� says Dean Crumlish, senior applications engineer at (Canton, MA, USA), �provided, of course, that time is not an issue.� Stepping in rapid succession through a sequence of precise x and y coordinates only a few centimeters apart becomes increasingly difficult as speed and precision demands rise. Positioning tasks in biomedical applications are especially challenging. Travel is scaled down to millimeters, accuracy tightened to microns, and positioning time is counted in milliseconds. Traditional instruments for positioning slides, test tubes, and microarrays have depended on leadscrew mechanisms. �Today�s demand for higher throughput�which translates into higher acceleration, speed, and accuracy�has run into mechanical limitations,� says Crumlish. Friction and rotational inertia slow down the process at the expense of both accuracy and cost. Enter Copley�s direct-drive Micro Linear motors, which reportedly achieve fast throughput and high reliability in a low-cost package. Their design is very simple. It consists of two basic parts, the thrust rod and the forcer. The thrust rod contains high-intensity permanent magnets. The load-carrying forcer is supported by low-friction bearings and incorporates electrical drive coils in a lightweight polymer. The forcer surrounds the thrust rod, and is propelled along the thrust rod�s length by digitally controlled magnetic fields. Tools for holding slides and test tubes are mounted directly onto the forcer. The motor�s tubular design features a 0.016-in. symmetrical air gap between the fixed and moving components. This gap introduces a very significant application benefit: it obviates the need for exact alignment between the forcer and the thrust rod. By relaxing the force/rod concentricity specifications, the gap simplifies the motor�s integration into high-performance positioning stages. Sinusoidal coil excitation
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Electric linear actuators have an output rod that provides linear motion via a motor driven ball screw, lead screw, or ACME screw assembly. The actuator's load is attached to the end of a screw or rod and is often unsupported.
Thrust bearings are designed for pure thrust loads, and can handle little or no radial load. The rolling element in a thrust bearing can be a ball, needle or roller.
Babbitt bearings are rotary bearings (no rolling elements) with special alloys poured into place in the bearing housing.
Linear Slides and Linear Stages
Linear slides are simple linear motion devices composed of a stationary base and a moving carriage. Linear stages are slides with a drive mechanism that provide controlled, precise positioning along a linear axis.
Hydraulic cylinders are actuation devices that utilize pressurized hydraulic fluid to produce linear motion and force.
The ACT is a high performance, cost-effective linear-servomotor-driven actuator that is faster and more accurate than a ball screw or belt-drive without the costly, time-consuming maintenance ball...
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The tubular linear motor has only two components, the rod and the forcer. This simple configuration for providing linear thrust is used as the base for all motion solutions.
Linear Electric Motors...
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