The problem with conventional bearings
Every rotating machine needs bearings to hold its shaft. In most fans, pumps and compressors this is done with ball, roller or plain bearings. They carry the shaft, but parts are in contact and need oil or grease.
That brings three things you have to live with: friction that turns energy into heat, lubrication that must be topped up, changed and kept clean, and wear on the parts that touch.
The basic idea: the shaft levitates
In a magnetic bearing, electromagnets sit around the shaft. With magnets on several sides, the shaft can be held in the centre of the bearing with a small air gap around it.
Because nothing touches inside the bearing, there is no mechanical friction and no lubricating oil in the bearings. A levitating shaft is not stable on its own, however, so the bearing needs sensors and control.
How an active magnetic bearing works
Electromagnets pull on the shaft with a force that can be adjusted by changing the current. Position sensors measure where the shaft is at all times, without touching it.
A controller reads the sensors and continuously adjusts the current in each magnet. If the shaft moves slightly towards one side, the pull from that side is reduced and the pull from the other side increased.
A machine normally has radial bearings that hold the shaft sideways and an axial (thrust) bearing that holds it lengthwise. Backup bearings catch the shaft if levitation is lost, so the machine can stop in a controlled way.
What it means in practice
Oil-free bearings: there is no lubricating oil in the bearings to change or to leak into the process. This matters where air or water must stay clean, such as aeration in wastewater treatment and water treatment in aquaculture.
No contact in the bearings during operation, so the bearings do not wear from metal-to-metal contact. And the controller always knows where the shaft is, which can be used for condition monitoring.
What a specific machine saves depends on the machine, the process and what it is compared with. We assess that for each project.
Talk to an engineer
Nordiclev supplies maglev turbo blowers, vacuum pumps, air compressors, chillers, heat pumps and ORC waste heat generators to industry in the Nordic region. Send us the operating data you have, and one of our engineers will look at whether magnetic bearings suit your process.
About this article: this is general information, not a recommendation for a specific plant, an offer or a guarantee. How a machine performs depends on, among other things, operating conditions, load profile, installation, control and maintenance. For any delivery, the technical data and terms in the offer and contract for that specific machine apply.