Analysis of Microparts Dynamics Fed Along on an Asymmetric Fabricated Surface with Horizontal and Symmetric Vibrations

Devices to feed along microparts, such as ceramic chip capacitors and resistors, have become more common, due to their use in sorting, inspecting, and shipping mass produced microparts. In microparts feeding, to feed along microparts in one direction, the driving force applied to each micropart must vary according to the direction of motion of the micropart. Especially, the motion of microparts smaller than submillimeter can be affected by not only inertia but also adhesion which is caused by electrostatic, van der Waal's, intermolecular forces, and surface tension. Now we have developed a novel microparts feeder applied an asymmetric fabricated surface, for example, sawtoothed surface, as a feeder table (Figure 1) (Mitani, 2006). The asymmetric fabricated surface can feed along microparts in one direction using horizontal and symmetric vibrations because contact between a micropart and the asymmetric fabricated surface varies according to the direction of motion. In order to formulate the dynamics of micropart, we need to analyse driving force and adhesion according to these contacts. In this chapter, we developed micropart dynamics considering the effect of contact. Sawtoothed silicon wafers with various pitch were applied for feeder table, and also 0603 (size, 0.6 x 0.3 x 0.3 mm: weight, 0.3 mg) capacitors were applied for microparts. First, we analysed contact between a micropart and a sawtoothed surface. Each surface profile model was approximated by a linear polynomial based on measurements using a microscopy system. Secondly, we derived dynamics including the effect of adhesion. We analysed contact between both approximated models, because both inertia caused by feeder vibrations and adhesion vary according to contact. Supposing that adhesion occurs in the direction vertical to the tangent and also adhesion acts when the distance between two surface models is smaller than an adhesion limit, we obtained an adhesion model. Then the adhesion model parameters were identified using the results of friction angle measurement experiments of microparts. Finally, we assessed the dynamics derived above. We firstly conducted feeding experiments of microparts using various pitch of sawtoothed surface with the same driving and