Dry buzzing stabilises the contact and also fixes or aligns any minor physical alignment defects. By operating the Reed Switches at no load condition, at special multiple high frequencies, the "buzz" adds the required contact area stability.
As the reed switches are not connected to any load during the dry buzzing operation, there is no load wear-out of the Reed Switch contacts. Furthermore, since the blades and surfaces align better after this process, the longevity of the reed switch is also enhanced.
The number of operations that a reed switch needs to be buzzed depends on the design of the reed switch and smaller reed switches may require more buzzing operations. Reed Switches with better blade-glass-seal alignment also require less buzzing than ones with slight misalignment, but still within tolerance. Static Contact Resistance and Variable Contact Resistance drop after dry buzzing, which indicates a more stable contact. Buzzing more than required will be counter productive and will slowly lead to higher contact resistance levels again.
The reed switches are aligned in to a large coil which is controlled by a function generator at capable of going up to 300 Hz. The coil design also is if importance the it needs to provide sufficient magnetic drive to all the reed switches kept within it during the buzzing operation. It is usually best practice to have a time controlled coil so that unnecessary excess buzzing operations are not done.
After this process step, the reed switches are taken for AT adjustment and sorting/grading, followed by visual inspection on a microscope or automated digital camera.
