MEDER electronic ABOUT MAGNETS Magnets and their specifications Magnets are available in multiple specifications on the net force as well as a different flux density. Additionally market. Almost all dimensions and geometries can be to dimension and material, other factors exist that define realised. To activate the reed switch a magnet (magnet the energy of a magnet. These are mounting position, field) is needed. The different magnet materials have environment and other magnetic field witch influence either more positive or negative specifications, depend - the interaction between reed sensor/switch and mag- ing on the dimension and geometries as well as on the net. In applications were a magnet is used to activate environment. Most preferred and used forms are cyl- a reed sensor/switch, the environmental temperature inders, rectangles, rings and discs. Depending on the needs to be considered (in the application as well as different requirements, magnets can be magnetised in in storage). High temperatures can cause irreversible many different ways (see picture 37). damage and will have heavy impact on the magnetic force and the long term stability. AlNiCo magnets are Furthermore each magnet material has a different mag- best suitable for applications up to 450C. (Figure 37. An assortment of magnets are shown. Magnets can be formed and made into almost any shape.) www.meder.com 41ABOUT MAGNETS MEDER electronic AlNiCo - Magnets General Information to magnet mate- rial Magnets have reversible and irreversible demagneti- AINICo Features Standard geometric and magnetization sation specifications. Be specially careful with shock, Rectangle Cylinder vibration, strong and close external magnetic fields as working temperature well as high temperatures. All these factors influence o from -250 to 450 C low temperature the magnetic force and the long term stability in differ- coefficient ent intensities. Preferably the magnet is mounted on the moving part of the application. Professional tuning of magnet and reed switch can improve the functionality of the whole sensor-magnet system. Raw materials for AlNiCo magnets are aluminium nick- el, cobalt, iron and titanium. AlNiCos are produced in a LOW HIGH sintering - casting procedure. The hard material needs costs Ferrite AlNiCo NdFeB SmCo to be processed by grinding to be cost effective. Due to energy (WxHmax.) Ferrite AlNiCo SmCo NdFeB its specifications, the best dimension is a remarkably working temperature NdFeB Ferrite SmCo AlNiCo longer length than its diameter. In combination with reed corrosion - resistant NdFeB SmCo AlNiCo Ferrite sensors / switches we recommend a length / diameter opposing efi ld - resistant AlNiCo Ferrite NdFeB SmCo ratio of more than 4. AlNiCo magnets have an excellent temperature stability. Negative are the high raw material mechanical strength Ferrite SmCo NdFeB AlNiCo prices. Cylindercal AlNiCo magnets can be used with all temperature coefficient AlNiCo SmCo NdFeB Ferrite MEDER reed sensors / switches without any problems. AINiCo Magnetic Values according to DIN Min. Typ. Max. Units 17410 (B x kJ/ Energy Product H) 35 39.8 3 m max. Remanence 1210 mT Reverse Temperature Coefficients 0.02% %/K of B r Coercivity H 47.0 51.3 kA/m cB Coercivity H 48.0 51.7 kA/m cJ Reverse Temperature - - - %/K Coefficients of H cJ 3 Density 7.4 g/cm o Max. Operating Temperature 450 C All details correspond to manufacturers information www.meder.com 42