Advantages of Using Servo Motors and Direct Drive Technology
The changing needs in the manufacturing sector are making it necessary for businesses to rethink their infrastructure investments and the technology they use. According to one article found in Material Handling & Logistics, the entire supply chain may be poised for a transformation as technological innovations become more prevalent. This includes the use of robotics, the Internet of Things, and more precise components, such as the servo motor, for better processes.
We cannot deny the importance of servo motors, robotics, and other automated systems in this industry, as manufacturers expect a lot of changes in the way goods are packaged today and in the future. With these technologies, processes will become faster and more efficient. For example, robotic cutting machines, together with automated weighing scales and laser sensors, can quickly determine the correct sizes required for packaging various items.
How Do Direct Drive Motors Work?
Direct drive technology works by using electromagnets, which are winded onto the rotor. The rotor is set within the stator, which is mounted on the motor’s shaft. When the winding is supplied with power (electricity), an electromagnetic field is produced, which either repels or attracts the rotor’s magnets. Controlled motion is produced when appropriate power commutation or switching is applied to the winding.
Direct drive motors do not make use of a gearbox, coupling, and a set of chains or belts. Instead, they are directly attached to the load, which means that there is no backlash, hysteresis, or lost motion in any movement direction. These motors are typically frameless, compact in size, and have low energy consumption, which makes integration in most applications easy. These are just some of the reasons why many design engineers prefer to use direct drive motors.
Advantages of Direct Drive Technology
- Improved accuracy
- Excellent dynamic performance
- Compact size
- Low torque ripple
- High reliability
- Low acoustic noise
- High energy efficiency
- Low cooling requirements
- Little to no maintenance needed
- Resistance to shock and easy installation due to its relatively large air gaps
Difference Between Servo Motor and Direct Drive Technology
Typical servo motors can run at around 6,000 revolutions per minute (rpm), which is too fast for most applications. This is why a gearhead is used to reduce its speed and gain torque. On the other hand, direct-drive motors provide lower speed and higher torque compared to a conventional rotary servo motor. They allow the load to be mounted directly on the motor without the use of gear reduction.
To produce high torque, direct drive motors use high pole counts. This also reduces the need for gearbox and servo motor combination. You get to remove all the mechanical components that produce resonance and backlash.
Two Primary Types of Direct Drive Motors
The two main types of direct drive motors are direct drive rotary motors and direct drive linear motors. Of the two, the rotary versions are more frequently used.
Direct drive rotary motors
A direct-drive rotary motor can be any servo drive that’s directly connected to the load. It’s designed to have lower speed and high torque capabilities with direct coupling. This type of motor removes the need for mechanical transmission components and more couplings. This provides many advantages over traditional servo motors that use conventional mechanisms, such as gearboxes, belts and pulleys, and ball screws.
By using a direct drive rotary motor, the part count is reduced, reliability is improved, audible noise is decreased, and the need for maintenance is lowered. This motor is available in a variety of styles, including frameless, housed, or semi-housed.
Direct drive linear motors
A direct-drive linear motor is essentially a type of rotary motor that’s laid out flat and mounted directly on the driven load. The removal of mechanical transmission components allows this design to deliver amazing performance, dynamic speed, acceleration, stiffness, positional accuracy, and throughput. Using this motor also enables quiet operation, compact mechanical assembly, zero maintenance, as well as smooth and error-free motion. The two most common types of linear direct-drive motors are:
- Ironless linear motors. These motors have zero cogging because they have no coil slots. They also have no attractive forces between the magnet way and the coil assembly. These characteristics make these motors perfect for applications that require high acceleration of lighter loads with very low bearing friction, as well as optimization of constant velocity—even at very low speeds.
- Iron core linear motors. These motors are designed to produce low cogging forces, high motor constant (Km) for low thermal losses, and the highest-rated force per size. The high thrust forces of iron core linear motors make them ideal for maintaining stiffness during processing and machining, as well as moving and accelerating high masses.
Applications of Direct Drive Motors
You may not notice, but direct drive technology is quite common and present in various products.
- Hard drives
- VCR heads
- Sewing machines
- Washing machines
Very low rotational speeds
- Telescope mount
- Phonographic turntables
- Ski lift drive
- Railway vehicles
- Wind turbines
- Road vehicles
- Video game racing wheel controllers
- Cycles (unicycles and children’s tricycles)
Manual labor in the manufacturing industry is highly inefficient, which is why machines were created to automate some tasks. However, the traditional machines that use gearboxes and belt-drive systems are still not that efficient. That’s why manufacturers are starting to integrate custom robotics systems in their facilities for better efficiency and accuracy.
Custom-based robotics systems powered by more precise servo drives are the future of the manufacturing industry. And, we have only seen the tip of the iceberg—so to speak.
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