Annealing of Degreased Reed Blades
After the process of degreasing and surface cleaning, reed blades have to be put through an annealing process. This removes any magnetic remanence and also increases the magnetic permeability. A low magnetic remanence ensure that reed switches do not “stick” and better magnetic permeability ensures better magnetic sensitivity during magnet actuation. Annealing also softens the blades that were hardened during the pressing process.
Reed blades are loaded into a pot and then inserted into a gas furnace. The flushing of these reed blades with a special gas helps burns off surface impurities. A prescribed heating and cooling curve with dry and wet gases is followed, which results in soft annealed reed blades with a smooth surface grain structure. The reed blades are then cooled over several hours inside the furnace, unloaded and then inspected for grain structure and surface smoothness. A few samples of the annealed blades are then coated and sealed into glass tubes to check for magnetic remanence levels, after which the entire batch is sent for sputtering.