Evaluation of the human tactile sense to microtexturing on plastic molding surfaces

The purpose of this study was to develop a plastic molding with a distinguishing tactile character for various industrial applications. Grooved textures with pitches and depths ranging from several micrometers to several hundred micrometers were fabricated on plastic molding surfaces by first micromachining aluminum alloy molds, and then utilizing a vacuum hot-press procedure. The effect of texture shape on the human tactile sense was investigated by sensory evaluation and multivariate statistical analysis. The sensory evaluation revealed that tactile recognition depends on the pitch of the texture, and not on the height; an obvious change was observed at a pitch of around 100 μm. Force measurements revealed that this change in tactile response was caused by the coefficient of friction and force fluctuations.