Set to auto

Motors have automated many of the functions once carried out manually which means competition is intense to produce the right size and type. Colin Carter explains

People are getting lazier — and we all want products with automatic functions.

Think of the days when opening all the windows of your car was done manually, changing music meant lifting a lid to replace a record or tape and you had to get out of your chair to change television channels. Now the motor has increased its application base all over the world.

This uptake in consumer applications over the past 20 years has been mirrored in industry. The market is mature (industrial automation company GE Fanuc has just sold its eight millionth motor) and product ranges have to be closely targeted to sell. The common differentiators are size, noise and the power/cost ratio.

Size is important for many applications such as the tiny motors required to move digital camera lenses or handheld medical devices. Recent products where size has been a selling point include motors from Pittman’s series 1300 brushless DC servomotors, designed for use ‘where space may be minimal’, and Sanyo’s vibrating micro-motor with a profile of 3.4mm, aimed at circuit boards.

On larger motors, low noise is a particular selling point. Servotechnic’s Lin Engineering NEMA 17 motors are claimed to be quiet and offer high speeds and torques. Other companies, such as US motion control and drive technology specialist Agile Systems, claim noise has a direct effect on the motor’s speed and efficiency. It recently patented a system for removing electrical noise generated by motors, which it claims allows for more robust running and increased speed and efficiency.

Agile’s patented SILENTstep, is claimed to be a breakthrough hybrid technology drive for stepper-motors. The company claims it is able to eliminate stalling, reduce audible noise and increase motor speed without the need for encoder feedback.

Other than quieter, faster and more efficient motors, end-users are demanding, and manufacturers are producing, higher-power motors from smaller packages. One example is Danaher Motion’s new Portescap 16mm brushless motors, which are aimed at the medical field for use in respiratory support equipment and claimed to provide 50W of power from a package weighing 33g (just over an ounce).

EMS, a UK supplier of miniature stepping motors, ultrasonic motors and controllers, also offers an impressive amount of power in a limited amount of space. Its Electronic Commutated Motor (ECM) brushless drives are available in sizes ranging from 35mm in diameter up to 75mm and speeds up to 10,000rpm with a maximum output power up to 350W.

The drives can run under 20,000 hours of continuous operation, making them a durable drive for applications such as pumps and ventilation systems. Another feature is their reduced weight compared with similar-sized motors, which is achieved by using aluminium end shields and motor housing.

However, the trend is not all for smaller and lighter motors — traditionalists will be pleased that big motors are still in use and not likely to go the way of the steam engine just yet. WEG Electric Motors has delivered the largest motor it has ever made, to be installed by Cegelec at a wind tunnel for testing aircraft.

This behemoth of motors measures 7m x 5m, weighs more than 95 tonnes and is rated at 27MW, requiring its own 132kV grid connection. It is claimed to be the largest slip ring induction machine ever built and quieter and more efficient than its predecessor.

Like their miniature cousins, big motors are quieter and more efficient than ever, and are being installed in wind tunnels for testing aircraft

Another application of motors on a large scale is in the coal industry. At Scotland’s Clydeport coal terminal three huge stackers and reclaimers have been equipped with Flender Motox geared motors as part of a major refurbishment. These units can handle up to 2,800 tonnes of coal an hour and the plant has installed 20 dust-resistant geared motor units per stacker to achieve this.

Motors are also used for food applications, where cleaning in place is essential to prevent contamination of foodstuffs. For example, as part of a process to prepare and mix its fruit drink bases, David Berryman of Dunstable has employed all-stainless steel Ytron-Quadro motors from Marlin Stainless for its new high-shear mixers. The system has to cope with a 1,200kg vessel full of product and features total corrosion resistance as well as being IP66 rated so it can be cleaned by being hosed down.

A more exotic use of motors can be found in the entertainments industry. In Las Vegas, Cirque du Soleil’s ‘O’ show requires a motorised, battery-powered piano to operate in and out of water at every performance, for years on end. For safety reasons the motor had to operate at less than 24V. Empire Magnetics installed a ‘Hall Effect’ commutated three-phase brushless motor integrated with a cycloidal gearbox. This is essential for the show’s finale, which features the piano movement controlled by a performer with a joystick.

Even the ‘Red Planet’ is not a motor-free zone these days.

Maxon Motors has supplied 39 motors for use in this most extreme of environments in NASA’s Mars exploration rovers.

The rovers are mainly looking for signs of water on Mars, and components such as motors must be able to work over a large temperature range which can range from -120ºC to +25ºC. Motors are used for functions such as operating robotic arms, rock drills, vehicle steering, camera control and turning the wheels.