Angled leaf springs are positioned around the bottom circumference of the feeder bowl. A drive coil, or electromagnet, located under the bowl cycles at a frequency of either 60 or 120 hertz, pulling the bowl downward. The angled leaf springs force the feed bowl to rotate, moving screws up the inclined spiral track. Too much vibration can send lightweight fasteners flying. It's best to use a feeder bowl with a small diameter to avoid this problem.
Screws also can become magnetized while in the bowl, inhibiting correct feeding.
Lining the bowl with plastic also makes it quieter. Centrifugal Feeders Centrifugal feeders are designed for applications requiring high feed rates, gentle part handling, low noise levels and limited floor space. Rotary orienting feeders use centrifugal force to move screws to an outside flange where orientation is accomplished. These units offer several advantages over vibratory feeders. For instance, fast speeds of up to 2,000 inches per minute are possible vs. only 300 inches per minute maximum for their vibrating cousins.