Magnetisers & Magnetising Fixtures
A typical magnetising system would normally comprise of two components.
- A power source or “Magnet Charger”
- A coil system or “Magnetising Fixture”
As the magnetising fields and magnetising currents required for magnetisation are generally very high, specialist equipment is required. Magnet Chargers are machines designed to generate very high current pulses, anything from a few thousand amps to thirty thousand amps or occasionally higher. The pulses are generated from a bank of capacitors, which are charged up over a period of a few seconds depending on the size of the machine and then quickly discharged into a low impedance magnetising fixture. Pulse lengths are typically 10’s to 100’s of microseconds which are necessary to prevent the magnetising coils from overheating during operation.
Bunting Magnetics Europe manufactures and supplies a range of commercial magnet chargers for the magnetisation of all types or permanent magnets and/or assemblies. They utilise oil filled bipolar capacitors and high voltage semiconductor output devices as standard. They are PLC controlled with automatic fixture detection systems and fixture over temperature alarms. Our standard range includes:
Laboratory/Production Magnetisers –
- Suitable for magnetisation of small rare-earth magnets in either a production or laboratory environment.
- Energy 1kJ or 2kJ
- Output Voltage – 0-3000V
- Max output current – 30kA
- Minimum Current Rise time ~ 35µs
- Optional quick connect fixture plugs
- Optional automatic handshaking between Fixture and Magnet Charger
Large Production Magnetisers
- Minimum Dimensions: 800 x 2000 x 1200mm wide
- Single or Three Phase Supply
- Energy Range : 4kJ to 100kJ
- Output Voltage – 0-3000V or 0-5000V
- PLC interface for integration with production lines
- LAN interface for online production control
In addition to the standard magnetisers, Bunting Magnetics can supply custom made systems including small bench top magnetisers, magnet setters, or large production systems with multiple outputs and magnet test systems. Our technical department are happy to talk to customers to discuss requirements.
Magnetising Fixtures contain the coils which generate the required magnetic field when connected to a suitable magnet charger. These can be standard solenoids for magnetising single magnets or a custom designed arrangement of multiple coils for a multipole magnet or assembly.
Bunting Magnetics Europe has been manufacturing magnetising fixtures for many years. Almost every bonded NdFeB ring magnet manufactured at Bunting has a dedicated multipole fixture as well as a press tool. Bunting also supplies magnetising fixtures to customers who prefer to carry out the magnetisation on site or can offer a magnetisation service for customers own assemblies.
There are a wide range of multi-pole magnetisation patterns that can be generated using different types of fixtures. The most common types include
- Internal and External multipole radial field
- Internal and external multipole axial field
- Homopolar or radial field fixtures
- Halbach magnetisation
- Single axis solenoids
For very fine pole-pitch magnetisation requirements, the number of poles is limited by the physical space available for the fixture windings. With conventional wire wound fixtures, the minimum feasible pole-pitch is currently about 1.5mm.
Magnetic assemblies can also be magnetised depending on the arrangement. The most common type of assemblies magnetised at Bunting Magnetics are permanent magnet rotors for electrical machines. These could be as simple as a bonded NdFeB ring magnet mounted onto a steel hub or a complete permanent magnet rotor encased in a protective sleeve. There are considerable cost savings to be made in assembly times if rotors are magnetised post assembly. Please call our technical team to discuss your requirements.