Voice coil actuators and motors generate force when subjected to an electrical current or magnetic field. The coil within the motor is the only moving component and is usually attached to a moveable load with a device such as a voice coil valve. This design permits high-speed motion and accurate positioning. Voice coil motors are an effective alternative to electromechanical components such as servomotors. Voice coil systems don’t produce motion with gears or screws, nor do they generate heat.

There are two basic types of voice coil products: linear and rotary. Linear voice coil actuators and linear voice coil motors provide precision, linear motion over short distances. Rotary voice coil actuators and rotary voice coil motors provide precision, circular motion over short angles. Both types of voice coil products are used in many types of control applications, from drive mechanisms in computers to robotic assembly lines.

Performance Specifications

Performance specifications for voice coil actuators and voice coil motors include force constant, peak force, linear stroke, torque constant, and peak torque. Force constant is the force that voice coil actuators and voice coil motors develop per ampere-turn of coil excitation. It is specified in pounds per amp (lbs/amp) or in Newtons per amp (N/amp). Peak force is the maximum, continuous force developed by a linear voice coil actuator or voice coil motor. Torque constant is the torque a voice coil motor develops per ampere of coil excitation. It is usually specified in pounds per amp (oz-in/amp) or an equivalent unit. Angular stroke is the maximum angle of displacement for rotary voice actuators and rotary voice coil motors. Peak torque is another important parameter to consider when selecting a rotary voice coil device. Electrical time constant is the time it takes the current to reach 63.21% of its final value when the actuator is subjected to a step input voltage.

Compliance Standards

There are two major standards with which voice coil actuators and voice coil motors must comply: RoHS and WEEE. Restriction of Hazardous Substances (RoHS) is a European Union (EU) directive that requires manufacturers of electronic and electrical equipment sold in Europe to demonstrate that their products contain only minimal levels of the following hazardous substances: lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyl and polybrominated diphenyl ether.

RoHS became effective on July 1, 2006. Waste Electrical and Electronics Equipment (WEEE) is an EU directive that is designed to encourage the reuse, recycling and recovery of electrical and electronic equipment such as voice coil actuators and voice coil motors. WEEE establishes criteria and requirements for the collection, treatment, recycling and recovery of this equipment. It also makes producers responsible for financing these activities. For their part, retailers and distributors must provide a way for consumers to return used or obsolete equipment without charge. WEEE became effective on August 1, 2005.