FERRAM is the name of ARELEC's ferrite magnets. It is a crystalline compound of Iron, Oxygen and Strontium. This family provides the most economical magnetic energy, which is why it is so widely used. It is mainly used for applications in which there are no thermal or dimensional constraints.
Ferrams have a number of uses, of which a summary is provided below.
- when associated with pole-pieces, they constitute attraction components.
- bare or potted, they can attract small objects and they have good distance attraction properties: toys, magnetic drawing pins, schedules. Thin strike plates are not sufficient.
For electrotechnical applications, they are used in vibrators, they control reed switches or Hall effect sensors, they operate thermostats, etc.
When overall size is not too tightly limited, Ferrams provide the most cost-effective solution to a magnetic problem.
This material is oriented, pressed and then sintered at high temperature. Its magnetisation is therefore always carried out in a privileged direction (anisotropic direction).
These materials belong to the ceramics family.
They are extremely hard and brittle, which means they are fragile with respect to impacts.
Ferrites are unaffected by most chemicals, except strong acids.
Ferrams have a moderate remanent induction and a high resistance to demagnetisation.
Strontium ferrite is very flat (see the table on the opposite page).
Use under difficult conditions: presence of an antagonistic magnetic field, repulsion, storage temperature below ‑20°C.
This is normally carried out according to the thickness dimension. For well-defined applications (attraction by a bare Ferram, for example), we can carry out multipolar magnetisation one face.
These materials can be adhesively bonded, potted or flush-mounted, but they can only be machined with a diamond tool.
Because Ferrams are brittle parts by definition, a certain amount of flaking is inevitable but does not have any significant effect on magnetic results. We define the size of a splinter by the sum of its three dimensions.
E = A + B+ C.
However, this splinter will only be taken into consideration if each of its dimensions is greater than 0.5 mm. As standard we supply E8 grade Ferram: each splinter is less than 8 mm.
For smaller parts (refer to the table opposite), the standard grade is E4 (E < 4 mm).
For parts that need require visual quality, you can specify E4 grade, or even E2 grade if necessary.
The standard tolerances are:
- Length and width: ± 0.25 mm
- Thickness: ± 0.05 mm
If your assembly requirements demand tight tolerances, we can specially manufacture parts with the following tolerances:
- Length and width: ± 0.10 mm
or even: ± 0.05 mm
- Thickness: ± 0.03 mm
These tolerances must be specified for each individual case.
Special manufacture according to estimate for large production runs.
Our production units can manufacture parts with special dimensions and with variants:
- machining of notches, undercuts, grooves,
- marking, packaging into magazines,
- multi-pole magnetisation.
As our magnets are obtained by cutting up large sections, it is more cost-effective to choose exact sub-multiples without scrap.