1. Delivery of permanent magnets:

Handling magnetized magnets may cause major problems for transport and assembly. They might cause injury due to dangerous forces, attract dirt or may hard to be kept in their assembly location.

Thus the easy handling of unmagnetized magnets during transport and assembly often requires a magnetizytion of the fully assembled magnet system.

Possible reasons for the magnetization of magnet assemblies are:

• Easier handling and packaging
• Reduction of dirt attrction (e.g. iron dust)
• Reduced risc of injury
• In some magnet system the magnetic layout requires iron return paths for the stability of the magnets. This may be of high relevancy for AlNiCo or Colbald alloys.
• Better profitability in case of high quantities

Most of the permanent magnets are not magnetized directly after production. Sinter magnets for example are demagnetized completely due to the high sinter temperature. They have to be magnetized afterwards by application of a high external field.

Some plastic bonded magnets may be magnetized directly in the injection mold. However it often still is helpful to strengthen some weakly magnetized portions by application of a higher external field of an impuls magnetizer.

3. Creation of outer field:

Normally the outer field is generated in coils which are connected to impulse magnetizers. Magnets with lower saturation field strength might also be magnetized by other permanent magnets or DC magnetizers.

The required duration of the magnetizing does not play a roll in this case. The required time to turn an electron spin is in the nano seconds range.

It is more time critical to have the field proceed to the magnet, which itself may be conductive or it may be shielded by conductive materials.

Therefore the pulse frequency and shape has to be well consided when using an impulse magnetizer. Limiting are:

• Heat up of the magnetizing coil in slow pulses  faster pulses
• Eddy currents  slower Pulses

In accordance to a harmonic resonator the pulse frequency and the peak current are related to

• charge voltage
• capacity
• coil inductivity
• coil resistanca

Exponentially damped pulses:

In normal cases the magnetizing current shape is a sine half wave. Magnet systems, which include conductive materials like iron, aluminum etc., may be shielded by eddy currents. These eddy currents firstly shield the magnet from the outer field and secondly might create an opposite field on the sharp end of a sine half wave. The opposite field might demagnetize the magnets again. In this case an exponentially damped pulse shape is appropriate.

While a sine half wave magnetizer will take a big part of the pulse energy back into the capacitors at the end of the pulse, the exponentially damped pulse shape will burn all the enrgy in the coils resistance.

This may cause heat problems. For this reason the optimum pulse shape and peak field must be well considered.

For the most common magnet systems charging voltages between 450V and 3000 are appropriate in order to achieve the pulse frequencies which are required.

Higher voltages are required when:

• The coil has a very high inductivity (e.g. big magnet systems)
• The magnetizing impulse shall be high frequency (short cycle times)

Low voltages are required when:

• Eddy current cause problems (e.g. massive iron parts)
• Insulations must be thin (e.g. sharp pole transitions)
• The coil has a very low inductivity (e.g. small multipole systems)

Technology – Safety features

The usage of high voltages and energies requires a special focus on safety:

Usage of high quality components and a mature technology.

Many internal safety featuers:

• Voltage control (tripple)
• Current measurement (single)
• Coil resistance measurement (single)

Fast internal safety discharge in case of emergancy or errors

The insulation of our high voltage components is always tested with 1.5 times the usage voltage.