Until now. Sanki Co. (Nagoya, Japan) has developed vibratory feeders that are driven by piezoelectric resonators rather than electromagnetic coils. A piezoelectric resonator is a fine ceramic of lead titanate and lead zirconate. The resonator warps one way in response to an electric current in one direction, and it warps the other way in response to current in the opposite direction. Each resonator is paired with a leaf spring. Piezoelectric in-line feeders have two resonator-spring pairs. Piezoelectric bowls have three or four.
Distributed in North America by Mirai Inter-Technologies Systems Ltd. (Richmond Hill, Ontario, Canada), Sanki’s piezoelectric vibratory feeders have several advantages over electromagnetic feeders. Piezoelectric feeders consume 70 percent less energy than comparable electromagnetic feeders. They are unaffected by ambient conditions, and they do not generate heat.
Piezoelectric feeders do not subject parts to a magnetic field, which can be important for feeding sensitive electronic components, such as chip capacitors, chip resistors and connectors. In addition, the spring does not require adjustment. Once the feeder is assembled and set to operate at 50 or 60 hertz (depending on the available power), adjusting the resonance spring is unnecessary.
Piezoelectric feeders are shorter than comparable electromagnetic feeders, and a wide range of feed rates can be selected with the voltage control. Because a piezoelectric feeder is driven directly by leaf springs that oscillate at a high rate, the device can feed small, thin parts without jiggling. Piezoelectric feeder bowls can even feed powder.
Besides bowls, a number of in-line feeders are available. The smallest in-line feeder weighs 0.25 kilogram. The largest weighs 17 kilograms with a maximum chute weight of 5 kilograms and a maximum chute length of 700 millimeters.
Direct-mounted in-line feeders are the simplest of the in-line models and produce the highest feed rates. However, because the reactive force is directly transmitted to the mounting frame, this type of feeder should be limited to compact systems.
Alternatively, the in-line feeder can be installed between the drive unit and the mounting frame via an intermediate spring. This reduces the reactive force applied to the frame. These feeders handle medium-sized and large parts with minimal vibration.
A third type of in-line feeder is mounted to rubber support legs. This significantly reduces the reactive force, so that the feeder can be used on a standard desk top. It can be used for high-speed feeding of medium-sized and large parts.
For more information on piezoelectric feeders, call Mirai Inter-Technologies at 905-763-9442 or visit www.miraiintertech.com.