Influence of surface coating lubricity on aluminum fin-stock formability

Abstract

We studied the influence of surface coating lubricity on pre-coated aluminum fin stock formability using evaporative lubricants, which was widely used. We controlled the surface friction of pre-coated aluminum fin stocks from 0.05 to 0.8 by the lubricant layer with water-soluble resin coated on hydrophilic layer with alkaline silicate and poly acrylic acid. On the continuous piercing test, according as the surface friction of pre-coated aluminum fin stock was decreased, the wear of piercing tool was decreased and was protected increase of piercing edge R. In case of drowless type forming used bigger piercing edge R, the collar cracking of fins was increased. Therefore, we consider that it has effect of decreasing the collar cracking to decrease the surface friction. On the continuous shearing test, according as the surface friction of that was decreased, the wear of shearing tool was decreased, so that the shearing burr height was depressed. Moreover, in the process of expanding copper tube, according as the surface friction of that was decreased, ‘avec’ phenomenon (fin-pitch disorder of the finned coil) was decreased.