KHK magnetic gears and couplings: contactless transmission

KHK has added magnetic transmission to its range, a technology that drives one shaft from another without the parts ever touching, with no wear and no lubrication. It is applied to two product families: magnetic couplings and magnetic gears.

How does magnetic transmission work?

Instead of teeth or connecting elements, each part carries neodymium permanent magnets with alternating north and south poles. When one part rotates, the attraction and repulsion between the poles drive the other across a small air gap, or even through a wall, with no physical contact.

Advantages over conventional transmission

• No wear or particles: since the parts do not rub, no material debris is released.
• No lubrication: no oil or grease is needed, so there is no splashing or fumes.
• Transmission through a wall: motion passes through non-magnetic barriers such as plastic, glass or stainless steel, allowing fully sealed designs without gaskets.
• Quiet operation with less vibration.
• Misalignment tolerance: they accept small variations in distance and angle between shafts, which makes assembly easier.
• Overload protection: if the maximum torque is exceeded, the magnets slip and protect the rest of the machine, with no need for a torque limiter.
• Long service life: the magnets lose no more than 0.1% of their strength per year, around 1% over ten years.

Magnetic couplings

They connect two shafts rotating at the same speed without touching. In addition to the advantages above, they reduce the heat transferred from the motor to the driven side. The range includes:

• Cylindrical and disc-type couplings: the standard option, with a wide choice of models and short lead times.
• Sealed couplings: with a PVC cover for acidic environments or a stainless steel cover for underwater use.
• SmoothSlip couplings: they smooth out slipping in the event of an overload and reduce vibration.

Motion through a wall

Because there is no contact, motion can pass through the wall of a tank or housing. The container stays completely closed, with no seals or holes that could leak. This is a very useful solution for pumps, mixers driven from outside the tank, or containers holding liquids.

Magnetic gears

They work on the same principle, but also allow speed and torque to be changed between shafts. The gear ratio depends on the number of poles on each wheel: as with a conventional gear, speed can be reduced to gain torque, or vice versa. Currently available:

Bonded magnetic screw gears

They transmit motion between crossed shafts. They are the most cost-effective version of magnetic screw gears, with the magnets coated in epoxy resin.

Variable speed gears

Available in disc-type and cylindrical versions, they can reduce or increase speed and offer greater flexibility in designing the gear ratio.

Other models in the range are not available at the moment.

Applications

These features make magnetic transmission a very attractive option in sectors where cleanliness, maintenance and reliability are critical:

• Semiconductor manufacturing and cleanrooms, including vacuum environments.
• Robotics.
• Medical devices.
• Food processing, where the product-contact area can be fully sealed and is easier to clean.

More technical information on the KHK magnetic couplings and magnetic gears pages.

Contact us for more information and model availability. Our technical team will help you choose the most suitable solution for your project.