Preparing to Purchase Reed Switches
Reed switches are electromagnetic switches operated by an applied magnetic field. They are made from two or more ferrous reeds that are sealed into a glass tube filled with inert gas. The ferrous reeds inside the glass tube do not touch unless there is an applied magnetic field attracting them. When the ferrous reeds are in contact because of an applied magnetic field, electricity can flow around the circuit which allows the device to operate.
Reed switches are used in everyday applications such as in parking garages to let cars in and out, laptops to signal your computer to go to sleep, and cars to automatically lock your doors. They are used in a plethora of industries such as automotive, automation and robotics, security systems, and many more.
There are four families of permanent magnets that are commercially available to operate reed switches. These include Neodymium, Samarium Cobalt, Aluminum Nickel Cobalt, and Ferrite ceramic magnets. Factors such as operating temperature, demagnetizing effects, field strength, environmental characteristics, and available space for movement need to be considered before selecting a reed switch or sensor application.
Neodymium magnets are the strongest and highest energy magnets that are commercially available for reed switches. Even tiny neodymium magnets can be effective, which allows for the cost to be relatively low. In terms of operating temperature, some grades of these magnets can be used in environments up to 200 degrees Celsius. When the applied magnetic field is removed, neodymium magnets are still highly magnetic, and it takes an extremely large force to demagnetize this type of magnet. Neodymium magnets are not recommended in hydrogen atmospheres and require low operating temperatures.
Samarium Cobalt Magnets
Samarium Cobalt magnets are high energy, but not as high as Neodymium magnets. These types of magnets have the highest resistance to demagnetization and low corrosion resistance. Samarium magnets are best for high-performance applications, have excellent thermal stability, and can be used in temperatures up to 300 degrees Celsius. Samarium magnets are the most expensive magnet choice and can be prone to chipping.
Ferrite Ceramic Magnets
Ferrite ceramic magnets are the cheapest of all the types of magnets and can be used in up to temperatures of 300 degrees Celsius. This type of magnet has the highest corrosion resistance and the highest temperature coefficient. However, its mechanical strength and energy is the lowest compared to the other types of magnets available in reed switches. Another important component about Ferrite magnets is that they need grinding to meet tight tolerances and can be brittle.
At Apex, we can help you decide which type of magnet is best for your company to implement reed switches. We are available Monday through Friday 9 am to 5 pm EST. Call us at 1-304-257-1193 or send us a message.