Tribological Characteristics of Thin-Film Disks With and Without Mobile Lubricant

Lubricant on thin-film magnetic disks is divided into two parts. One is bonded lubricant that is fixed on disk surface and remains on disk surface after solvent rinsing. The other is mobile lubricant that can move on disk surface and is removed by solvent rinsing. It has been believed that mobile lubricant is imperative to design reliable hard disk drives. However, mobile lubricant would also be a cause of high friction between heads and disks. We started our studies on disks without mobile lubricant to find the possibility of disks with only bonded lubricant. In this paper, tribological characteristics of disks with and without mobile lubricant at the same lubricant thickness were compared using our transparent pin-on-disk wear tests. The results showed that pin wear was smaller on disks without mobile lubricant than those on disks with mobile lubricant in low load or slow speed conditions. The reason of this was considered to be the contact force increase by meniscus force due to lubricant bridge.