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MOTION CONTROL AT THE SPEED OF TECHNOLOGY™
Direct Drive Motors
A direct drive motor is any motor — rotary or linear — in which the load is directly coupled to the motor without mechanical transmission elements such as gearboxes, rack and pinions, or belt and pulley systems. In this system, the motor directly drives the load. The reduction in the amount of moving parts increases the efficiency of the system, creates a quiet and highly dynamic motor operation, and increases the lifespan of the system.
Direct Drive Motors We Carry
Types of Direct Drive Motors
Direct Drive Linear Motors
A direct drive linear motor is a rotary motor that is laid out flat, directly mounted onto the driven load. Direct drive linear motors are not as commonly selected as rotary motors.
Pancake Motors
Pancake motors, also known as printed armature motors, are another type of rotary direct drive motor. These motors are available in brushed or brushless DC motor versions where the armature windings are printed on a disc of non-magnetic insulating material. The armature disc is placed between two stator discs that have permanent magnets arranged with alternating north and south poles. The magnetic flux runs axially along the length of the motor and current runs radially (rather than axially, as in a traditional motor). This causes torque to be produced around the motor’s axis, according to the Lorentz force.
Linear Direct Drive Motors
Iron core linear motors can be either slotted or slotless, the more common being slotted. Slotted iron core linear motors have the highest force capabilities, but can experience significant cogging. Slotless iron core linear motors have less cogging and lower inertia, but have reduced force capability.
Ironless linear motors have a flat magnet with a forcer consisting of coils mounted to an aluminum plate. Ironless flat linear motors offer excellent velocity control with less force than other designs. A second variation of ironless linear motors has no cogging and can produce high acceleration and deceleration rates.
Direct Drive Rotary Motors
Direct drive rotary motors are often referred to as torque (or torquer) motors because of their ability to produce high torque at low speeds, even when stalled. Torque motors tend to be brushless, permanent magnet synchronous motors — much like a traditional servo motor, but with a higher pole count.
Direct drive rotary motors are constructed with housings or provided in frameless motor kit designs. Frameless direct drive rotary motors don’t include a housing, bearings, or feedback device, with these sub-components being provided separately and integrated by the OEM or end user.
Tubular Linear Direct Drive Motors
Tubular linear motors can be constructed with or without the iron in the secondary part. Their symmetrical design allows all the magnetic flux to be used for generating thrust force.
Other Types of Direct Drive Motors
- Housed Cartridge Direct Drive (Bearingless Motors)
- Voicecoil Motors
Benefits of Direct Drive Motors
Direct drive motors have the inherent benefit of eliminating mechanical components that can introduce backlash and/or compliance which degrades positioning accuracy and repeatability. This reduces load inertia and allows for more dynamic motor operation — i.e. higher acceleration and deceleration rates with heavier loads — with less overshoot and oscillation.
Without the need for additional transmission elements, direct drive motors also tend to be more compact than traditional motors making them easier to integrate into tight spaces. With fewer mechanical components, maintenance is reduced and mean time between failures (MTBF) is increased.
Other advantages include:
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Applications of Direct Drive Motors
Direct drive rotary motors are suitable for high speed, acceleration applications with fast starts and stops as well as applications where high positioning accuracy is needed. Some common applications include:
- SCARA robots
- Rotary tables
- Goniometers
- Gimbals
- Cocking/recoil mechanisms
Direct Drive Motor Manufacturers
Electromate is proud to offer several families of Direct Drive Servo Motors from different manufacturers including:
