Linear Actuator Screw Types
Linear actuators are used in the automotive, medical and farm industries to power vehicles, hospital beds and agricultural machinery. Linear actuators work through the coordinated motion of screws and nuts. The size and performance of linear actuators varies widely, and engineers must take a variety of safety, noise and performance factors into account when selecting a type of linear actuator screw.
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Selecting Type
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Engineers consider cost, performance and type of application when selecting a linear actuator screw. Lower performance screws are appropriate in applications where torque is low and machinery is not required to run for long periods of time. Industrial automotive and medical equipment necessitates high performance screws which tolerate repeated use.
Lead Screw
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Lead screw designs are the most simple, lowest cost and most widely used technology for linear actuators. Lead screws work by sliding the surface of a nut against the threads of a screw. The repeated friction can cause wear and tear and increase the need for replacement of parts. While lead screws cannot handle high torque, they are relatively quiet.
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Ball Screw
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Ball screws can handle heavier loads than lead screws because ball bearings help distribute the load and reduce the friction. Ball screws cost more than lead screws, but they deliver more thrust and precision. Disadvantages of ball bearings are noise and potential for fracture and failure under very large loads.
Planetary Roller Screw
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Planetary roller screws are arrangements of multiple screws around a nut, which deliver more torque than lead screws or ball screws. Planetary screws are more expensive, but necessary for robotics or other applications that require fitting into tight spaces. For the higher price, planetary screws last longer and require less maintenance.
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