How does a vibratory bowl feeder cause the parts to move up? When I first learned about bowl feeders I thought that there was some sort of rotation that would cause it to go up, but apparently it is caused by vibrating the bowl.
I do not understand how vibrations can cause a part to move upwards. From what I understand, vibrations will have a similar effect to reducing friction, which means that it would cause the parts to fall down the slope more easily.
How does it work? Is the vibration applied in a certain direction/rotation/etc. which causes this upward movement? Or is it just normal vibration?
There is an article describing vibratory bowl feeders here, and a YouTube video showing one in operation here.
 A: I found this answer at,
http://www.changeover.com/vibratorybowlfeeders.html
"Properly tuned, a feeder will vibrate properly but, by itself, vibration will do little more than make the parts bounce around. In order to make the parts move, the vibration must be focused in the desired direction. This is done by mounting the springs on an angle rather than vertically. As the feeder bowl rotates back and forth on its springs the angle causes it to move vertically as well. As it moves forward and up, friction pushes the part forward. As it moves back and down, the part falls vertically. This sawtooth motion can move parts gently at astonishing speeds."
A: The bowl feeder as well as its linear version based on the hysteresis of the involved spring-magnet device-system. Changing the frequency of the vibrations of the magnetic device you can make that the parts in the feeder will vibrate in standstill or will move backwards. A big difference in the load will do the same. Instead of electromagnets they use piezoelectric devices too, or for really big feeders simply an electro motor with a unbalanced weight on its axis. 
