Vertical orientation of short wires using a monolayer of spheres

ABSTRACT

The present work investigates the tendency of fine (mm-size) metallic wires to orient vertically in the interstices of a monolayer of close-packed spheres using simple vibrational action. In order to investigate main effects and to best match sphere and wire sizes, a full factorial design of experiments was performed for each sphere size used to build the monolayer. Analysis of variance (ANOVA) results show that wire geometric parameters (diameter and length) are the most significant parameters, and that machine or vibration type can also influence the extent of orientation. Over the range of largest sphere sizes (8–3 mm) the optimal orientation is achieved when sphere diameter and wire length are equal. Optimal ratio of wire diameter to interstitial diameter varies in the range of 0.2–0.6, increasing with decreasing sphere size. As expected, maximum obtainable vertical orientation decreases as sphere size decreases, as surface/static forces become significant and/or vibrational characteristics deviate from ideal.

KEYWORDS:

• Full factorial design
• monolayer of spheres
• vertical orientation
• vibration
• wire