What You Need to Know About Voice Coil Actuators
       By: Kelly Ashmore
Posted: 2014-02-15 00:32:02
A voice coil actuator is a magnetic device and type of linear actuator; designed to push and pull an object in a linear motion. The term voice coil comes from one of the earliest applications of the actuator; where it was used to vibrate the cone of a loudspeaker. The popularity of this application resulted in the term voice coil actuator.A voice coil exerts a certain amount of force, which results in an object moving in a linear motion in an application. Voice coil actuators can be used for fast and slow motions. They can be designed to meet different motion requirements of various industries.Types of Voice CoilsGenerally, there are two types of voice coils that are used in industrial applications:• Cylindrical Voice Coils: This type of voice coil consists of a cylindrical coil and a cylindrical magnet. The coil is connected to a power supply, which provides the electric current. When the power supply is turned on, the electric current runs through the coil and creates a magnetic field.• Rectangular Voice Coils: These coils are usually un-housed and do not comprise any bearings or shafts. Aluminum is used for constructing the coils, as aluminum is known for its light weight, and is reliable conductor of electricity. Rectangular voice coils are considered to be ideal for high speed movements, and are known for easy installation and operation.Guidelines for Voice Coil ConstructionThere are certain guidelines that must be taken into consideration when constructing a voice coil actuator:• Mechanical Considerations: Housing is usually designed for voice coil actuators depending on the needs of the client. The size of the housing depends on specifications such as length, height, width, and diameter. Engineers must consider the length of the linear stroke of the actuator, as strokes can be designed as full or mid strokes. The length of the shaft for the linear strokes must also be taken into consideration. • Electrical Guidelines: Engineers have to pay attention to aspects such as coil inductance and resistance. At rapid speeds, there is a possibility that the magnet will create a current but the electromagnetic field will induce a counter electromotive force or ‘back EMF’. This can cause immense problems in an application and thus, the actuator must be tested for back EMFs before delivery. Engineers have to work with the client and understand what will be the safe peak current and what should be the stalling current. The amount of force during the peak current should also be considered for proper actuator use.Benefits of Voice Coil ActuatorsThere are a few reasons why voice coil actuators are preferred over other types of actuators.• Simple construction
• Easier to control
• Protection against electric currents
• Low electrical consumption
• Requires a small amount of space in an application
• Thermal protection
• Low hysteresis
• They are designed to provide a force that is in conjunction with the electric current and velocity feedbackApplications of Voice Coil ActuatorsSimple design, speed, and power of voice coil actuator makes it a popular device for a variety of industrial applications:• They can be used in optical systems for mirror and lenses positioning
• Precision tooling positioning makes great use of voice coil actuators
• They are used as linear drives for cryogenic coolers and a variety of pumps
• They are known for their efficient work with battery powered systems and temperature sensitive devices
• Voice coil actuators are well-known for their use in semiconductor equipment, defense systems, and medical equipmentVoice coil actuators are popular magnetic linear motion devices, which are known for their versatility and long work life.
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