Permanent magnets are found in the electric-motor driving-transport systems of most warehouses and production-environments. However, magnets are also increasingly used for magnet couplings in exacting transport and production-lines components, including those at high temperatures, pressures, in a vacuum or in liquid and chemical processing. The advantage of this is a contactless magnetic coupling, opening up all kinds of intriguing and unexpected possibilities.
Contactless engineering with magnetic couplings in transport- and production lines
Bakker Magnetics in Science Park Eindhoven has been specialising in engineering and producing magnet assemblies for electric drives for 50 years. Electric motors with magnet assemblies are used the world over all over the world in countless warehouses and production lines. Less well known is the use of Bakkers’ magnetic couplings in these automated environments. ‘But that’s about to change’, says Bakker Magnetics’ Sales Engineer, Marc Jan Dercksen. ‘Contactless technology means forces can be transferred under critical conditions, without wall opening being required., thus neutralising the risk of leakage or pressure loss. What’s more, magnetic couplings are maintenance-free, and are resistant to extremely high temperatures, if the right magnets are used.’
“Contactless technology means forces can be transferred under critical conditions, without wall opening being required“
A magnetic coupling essentially comprises two magnets, positioned opposite each other – usually a multiple-magnet configuration – separated with an air gap. When one magnet rotates, the second one rotates too. There is no contact between the two magnets, and the magnetic fields even operate through a solid wall. Despite magnetic-coupling having been around for a while now, only in recent years has its industrial use risen. ‘Before that, magnetic couplings didn’t even occur to most transport and production-line developers and installers. Only now are they discovering the wealth of possibilities,’ says Marc Jan. ‘New magnet grades and fixing methods have also meant we can meet increasingly greater demands, in turn expanding the fields of application.’ Bakker Magnetics engineers and produces the magnetic couplings in the Netherlands. Magnets and certain series assemblies are manufactured in China through a joint venture with one of the country’s largest and most advanced magnet factories. ‘We nevertheless retain responsibility. Every magnet delivered from China to Bakker Magnetics in the Netherlands is therefore inspected in our quality laboratory, using highly accurate measuring equipment. Not a single defective magnet will be sent on to the customer. For Bakker Magnetics, the highest quality is always paramount’, Marc Jan adds.
To find out more about the full potential of magnetic couplings, Marc Jan mentions cites some examples of this technology in demanding situations: ‘Imagine a product has to undergo a particular process in an oven, taking place under extreme pressure and temperature. Due to the heat, the product can only be moved through the oven on special rollers. Each roller is driven by a contactless magnetic coupling fitted outside the oven, resulting in no pressure or temperature-loss, as well as a maintenance-free system With magnets in the magnetic coupling, we might opt for high-grade neodymium magnets or even samarium cobalt (SmCo) magnets, resistant to temperatures up to 300°C while retaining their magnetic properties. A production line including a large mixer blending caustic chemicals or hazardous liquids is another example where no leakage is desired, preferably with minimal maintenance. The rotor of the mixer is driven in a contactless manner, without a wall opening, feasible in an environment of up to 65 bars. A special magnetic-coupling design is the hysteresis coupling, with one of the two magnet configurations replaced with aluminium or copper. These are nonferrous materials not displaying ferromagnetic behaviour, enabling the coupling to slide. This allows you to set the torque, a maximum force executing the operation; ideal for a screw bottle-top production line, for instance.’
“Another feature of hysteresis magnetic couplings is their use in slowing down motion“
Another feature of hysteresis magnetic couplings is their use in slowing down motion,’ says Marc Jan: ‘Hysteresis couplings are used in rollercoasters: a linear magnetic brake and an aluminium plate. It works every time, even during a power outage. This same principle is also suitable for slowing down items with excess velocity at certain points on a warehouse conveyor belt. Magnetic couplings can also be used as product components, such as a in large industrial drive for a ventilator. Vibrations, noise and failures arise because the alignment of shaft and bearings in such a ventilator is usually not perfect, and due to constant wear and tear over time. A contactless magnetic coupling in the centre the shaft resolves these alignment issues at once. We can create a coupling such as this for an extremely high rotational speed of up to 3500 rpm. The solution also means maintenance engineers don’t have to spend all day replacing bearings.’
Customisation and Innovative
Niels believes the magnetic coupling is gaining in popularity. ‘It’s a fantastic, future-oriented technology with multiple benefits in terms of safety, reliability and speed. What’s more, it’s also a clean technology; sustainable and contactless. It nevertheless needs a higher profile, and engineers, installers and product developers need to be aware of this technology exists. That’s when they’ll come looking for us.’ Marc Jan therefore invites anyone with a good idea involving magnetic couplings to get in touch. Moreover, he offers them something many others can’t: ‘We don’t supply a standard range, but instead offer customised solutions so that the magnetic coupling ties in with the customer’s design, rather than the other way around. Dimensions, force, torque, high-demand conditions… You name it, we can handle it. Even a magnetic coupling with a one-metre diameter or a torque of up to 550 Nm: This technology is our specialism. We do the sums, perform simulations, and are a knowledge system partner from start to finish: this is how we deliver our customised, total solution for customers wishing to join in creating something new, something unusual and, in first and foremost, something better. The true definition of co-creation. This is smart magnetic engineering by Bakker Magnetics.’