2005 Volume 42 Issue 2 Pages 110-115
The performance of twin roller system developed for size classification of spherical particles has been studied experimentally. The particles used are solder balls of several hundreds micrometers in diameter. The experimental apparatus consists of a hopper, a feeder, a twin roller unit, and a series of containers. The two rollers are arranged at a certain inclination with a small opening angle. The particles that are fed from the feeder move along the gap between the rollers, and fall down at a point where the width of the gap exceeds the diameter of the particles; then they are collected into the containers. The velocity of particles moving on the rollers is the important parameter to determine the total number of particles classified per unit time. The experimental results show that the particle velocity is proportional both to the angular velocity of the rollers and to the tangent of the inclination angle. The accuracy of the size classification is within +/-0.1%.