Ferro-magnetic Parts

Reed Switches utilize a nickel-iron alloy, sputter coated with additional Ruthenium to render it ferromagnetic while maintaining low magnetic remanence. This specific composition is crucial for the functionality of reed switches. When a magnet approaches, the reed blades within the switch act as conduits for magnetic flux, attracting each other to close the switch. Upon magnet removal, the alloy does not retain magnetism, allowing the switch to open. It is with great process control that the magnetic remanence of reed switches is kept near zero to avoid it withholding any magnetism when an actuating magnet is absent.

However, positioning reed switches near ferromagnetic materials like mild steel screws or fixtures can pose challenges. These materials can become magnetized by external magnets and retain that magnetism even after the magnet is removed. This residual magnetism interferes with the reed switch’s operation in two primary ways:

Firstly, by diverting magnetic flux away from the switch, reducing the magnetic field necessary for actuation, thereby reducing the actuating distance. Secondly, by potentially keeping the switch closed due to their own magnetism.

Industry guidelines typically recommend maintaining a distance of at least 100 mm between reed switches and any ferromagnetic mounting parts or screws. This separation helps to prevent such interference, ensuring the reed switch operates reliably within its specified parameters, although it is always better to use non-ferro-magnetic mounting parts in and around the vicinity of reed switches and reed sensors. We often use carefully selected grades of Brass or non-magnetic Stainless Steel.

According to experts in magnetic sensor technology, such as those cited by reputable sources like electronics manufacturers and industrial automation specialists, the proximity of ferromagnetic materials to reed switches can significantly impact their performance. The importance of careful positioning and installation practices is done to mitigate unintended effects on reed switch functionality in various applications, from automotive sensors to consumer electronics.